diff options
author | gj <gj@FreeBSD.org> | 1997-01-15 22:33:16 +0000 |
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committer | gj <gj@FreeBSD.org> | 1997-01-15 22:33:16 +0000 |
commit | b4283751defeae196f81da1b6d60b2ebe42e4d7a (patch) | |
tree | efb8701f72a37e4de54bf27731c976e0c1ebdc97 /gnu | |
parent | 5a3eeda46b960f4ac9faa83cb378cd2f9a7de905 (diff) | |
download | FreeBSD-src-b4283751defeae196f81da1b6d60b2ebe42e4d7a.zip FreeBSD-src-b4283751defeae196f81da1b6d60b2ebe42e4d7a.tar.gz |
changes required in the doc directory for making the gdb info
files using the texi sources in /usr/src/contrib/gdb/gdb/doc.
I put a pointer to /usr/src/contrib/libreadline/doc into
Makefile.inc in the hope that the appropriate files would be
picked up.
This is based on /usr/ports/devel/gdb.
2.2 candidate ?
Diffstat (limited to 'gnu')
-rw-r--r-- | gnu/usr.bin/gdb/doc/GDBvn.texi | 1 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/Makefile | 7 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/all-cfg.texi | 117 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/annotate.texi | 708 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/gdb-cfg.texi | 3 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/gdb.texinfo | 8921 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/gdbint.texinfo | 2669 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/h8-cfg.texi | 47 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/inc-hist.texi | 155 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/remote.texi | 1424 | ||||
-rw-r--r-- | gnu/usr.bin/gdb/doc/stabs.texinfo | 4035 |
11 files changed, 9 insertions, 18078 deletions
diff --git a/gnu/usr.bin/gdb/doc/GDBvn.texi b/gnu/usr.bin/gdb/doc/GDBvn.texi deleted file mode 100644 index c891e56..0000000 --- a/gnu/usr.bin/gdb/doc/GDBvn.texi +++ /dev/null @@ -1 +0,0 @@ -@set GDBVN 4.13 diff --git a/gnu/usr.bin/gdb/doc/Makefile b/gnu/usr.bin/gdb/doc/Makefile index 9e9c9ea..f124be4 100644 --- a/gnu/usr.bin/gdb/doc/Makefile +++ b/gnu/usr.bin/gdb/doc/Makefile @@ -1,8 +1,13 @@ INFO = gdb gdbint stabs annotate +GDBDIR= ${.CURDIR}/../../../../contrib/gdb +.PATH: ${GDBDIR}/gdb/doc + INFOSECTION= "Gdb Documentation" INFOENTRY_annotate= "* GDB annotation: (annotate). Annotations for the GNU Debugger (GDB)." -MAKEINFOFLAGS += -I ${.CURDIR}/../../../../contrib/libreadline/doc +MAKEINFOFLAGS += -I ${GDBDIR}/gdb/doc +MAKEINFOFLAGS += -I ${GDBDIR}/../libreadline/doc +MAKEINFOFLAGS += -I ${GDBDIR}/readline/doc .include <bsd.info.mk> diff --git a/gnu/usr.bin/gdb/doc/all-cfg.texi b/gnu/usr.bin/gdb/doc/all-cfg.texi deleted file mode 100644 index ec64da1..0000000 --- a/gnu/usr.bin/gdb/doc/all-cfg.texi +++ /dev/null @@ -1,117 +0,0 @@ -@c GDB MANUAL configuration file. -@c Copyright (c) 1993 Free Software Foundation, Inc. -@c -@c NOTE: While the GDB manual is configurable (by changing these -@c switches), its configuration is ***NOT*** automatically tied in to -@c source configuration---because the authors expect that, save in -@c unusual cases, the most inclusive form of the manual is appropriate -@c no matter how the program itself is configured. -@c -@c The only automatically-varying variable is the GDB version number, -@c which the Makefile rewrites based on the VERSION variable from -@c `../Makefile.in'. -@c -@c GDB version number is recorded in the variable GDBVN -@include GDBvn.texi -@c -@c ---------------------------------------------------------------------- -@c PLATFORM FLAGS: -@set GENERIC -@c -@c Hitachi H8/300 target: -@set H8 -@c Hitachi H8/300 target ONLY: -@clear H8EXCLUSIVE -@c -@c remote MIPS target: -@set MIPS -@c -@c SPARC target: -@set SPARC -@c -@c AMD 29000 target: -@set AMD29K -@c -@c Intel 960 target: -@set I960 -@c -@c Tandem ST2000 (phone switch) target: -@set ST2000 -@c -@c Zilog 8000 target: -@set Z8K -@c -@c Lucid "Energize" environment: -@clear LUCID -@c -@c Wind River Systems VxWorks environment: -@set VXWORKS -@c -@c ---------------------------------------------------------------------- -@c DOC FEATURE FLAGS: -@c -@c Include change-from-old? -@set NOVEL -@c -@c Bare-board target? -@clear BARETARGET -@c -@c Restrict languages discussed to C? -@c This is backward. As time permits, change this to language-specific -@c switches for what to include. -@clear CONLY -@c Discuss Fortran? -@set FORTRAN -@c -@c Discuss Modula 2? -@set MOD2 -@c -@c Specifically for host machine running DOS? -@clear DOSHOST -@c -@c Talk about CPU simulator targets? -@set SIMS -@c -@c Is manual stand-alone, or part of an agglomeration, with overall GPL? -@clear AGGLOMERATION -@c -@c Remote serial line settings of interest? -@set SERIAL -@c -@c Discuss features requiring Posix or similar OS environment? -@set POSIX -@c -@c Discuss remote serial debugging stub? -@set REMOTESTUB -@c -@c Discuss gdbserver? -@set GDBSERVER -@c -@c Refrain from discussing how to configure sw and format doc? -@clear PRECONFIGURED -@c -@c Refrain from referring to unfree publications? -@set FSFDOC -@c -@c ---------------------------------------------------------------------- -@c STRINGS: -@c -@c Name of GDB program. Used also for (gdb) prompt string. -@set GDBP gdb -@c -@c Name of GDB product. Used in running text. -@set GDBN GDB -@c -@c Name of GDB initialization file. -@set GDBINIT .gdbinit -@c -@c Name of host. Should not be used in generic configs, but generic -@c value may catch some flubs. -@set HOST machine specific -@c -@c Name of GCC product -@set NGCC GCC -@c -@c Name of GCC program -@set GCC gcc - diff --git a/gnu/usr.bin/gdb/doc/annotate.texi b/gnu/usr.bin/gdb/doc/annotate.texi deleted file mode 100644 index 7716535..0000000 --- a/gnu/usr.bin/gdb/doc/annotate.texi +++ /dev/null @@ -1,708 +0,0 @@ -\input texinfo @c -*-texinfo-*- -@c %**start of header -@setfilename annotate.info -@settitle GDB Annotations -@setchapternewpage off -@c %**end of header - -@set EDITION 0.5 -@set DATE May 1994 - -@ifinfo -This file documents GDB annotations. - -This is Edition @value{EDITION}, @value{DATE}, of @cite{GDB -Annotations}. Copyright 1994 Free Software Foundation - -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -@ignore -Permission is granted to process this file through TeX and print the -results, provided the printed document carries copying permission -notice identical to this one except for the removal of this paragraph -(this paragraph not being relevant to the printed manual). - -@end ignore -Permission is granted to copy and distribute modified versions of this -manual under the conditions for verbatim copying, provided also that the -entire resulting derived work is distributed under the terms of a -permission notice identical to this one. - -Permission is granted to copy and distribute translations of this manual -into another language, under the above conditions for modified versions. -@end ifinfo - -@titlepage -@title GDB Annotations -@subtitle Edition @value{EDITION} -@subtitle @value{DATE} -@author Cygnus Support -@page -@vskip 0pt plus 1filll -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -Copyright @copyright{} 1994 Free Software Foundation -@end titlepage - -@ifinfo -@node Top -@top GDB Annotations - -This file describes annotations in GDB, the GNU symbolic debugger. -Annotations are designed to interface GDB to graphical user interfaces -or other similar programs which want to interact with GDB at a -relatively high level. - -This is Edition @value{EDITION}, @value{DATE}. - -@menu -* General:: What annotations are; the general syntax. -* Server:: Issuing a command without affecting user state. -* Values:: Values are marked as such. -* Frames:: Stack frames are annotated. -* Displays:: GDB can be told to display something periodically. -* Prompting:: Annotations marking GDB's need for input. -* Errors:: Annotations for error messages. -* Breakpoint Info:: Information on breakpoints. -* Invalidation:: Some annotations describe things now invalid. -* Running:: Whether the program is running, how it stopped, etc. -* Source:: Annotations describing source code. -* TODO:: Annotations which might be added in the future. -* Index:: Index -@end menu -@end ifinfo - -@node General -@chapter What is an Annotation? - -To produce annotations, start GDB with the @code{--annotate=2} option. - -Annotations start with a newline character, two @samp{control-z} -characters, and the name of the annotation. If there is no additional -information associated with this annotation, the name of the annotation -is followed immediately by a newline. If there is additional -information, the name of the annotation is followed by a space, the -additional information, and a newline. The additional information -cannot contain newline characters. - -Any output not beginning with a newline and two @samp{control-z} -characters denotes literal output from GDB. Currently there is no need -for GDB to output a newline followed by two @samp{control-z} characters, -but if there was such a need, the annotations could be extended with an -@samp{escape} annotation which means those three characters as output. - -A simple example of starting up GDB with annotations is: - -@example -$ gdb --annotate=2 -GDB is free software and you are welcome to distribute copies of it - under certain conditions; type "show copying" to see the conditions. -There is absolutely no warranty for GDB; type "show warranty" for details. -GDB 4.12.3 (sparc-sun-sunos4.1.3), -Copyright 1994 Free Software Foundation, Inc. - -^Z^Zpre-prompt -(gdb) -^Z^Zprompt -quit - -^Z^Zpost-prompt -$ -@end example - -Here @samp{quit} is input to GDB; the rest is output from GDB. The three -lines beginning @samp{^Z^Z} (where @samp{^Z} denotes a @samp{control-z} -character) are annotations; the rest is output from GDB. - -@node Server -@chapter The Server Prefix - -To issue a command to GDB without affecting certain aspects of the state -which is seen by users, prefix it with @samp{server }. This means that -this command will not affect the command history, nor will it affect -GDB's notion of which command to repeat if @key{RET} is pressed on a -line by itself. - -The server prefix does not affect the recording of values into the value -history; to print a value without recording it into the value history, -use the @code{output} command instead of the @code{print} command. - -@node Values -@chapter Values - -When a value is printed in various contexts, GDB uses annotations to -delimit the value from the surrounding text. - -@findex value-history-begin -@findex value-history-value -@findex value-history-end -If a value is printed using @code{print} and added to the value history, -the annotation looks like - -@example -^Z^Zvalue-history-begin @var{history-number} @var{value-flags} -@var{history-string} -^Z^Zvalue-history-value -@var{the-value} -^Z^Zvalue-history-end -@end example - -where @var{history-number} is the number it is getting in the value -history, @var{history-string} is a string, such as @samp{$5 = }, which -introduces the value to the user, @var{the-value} is the output -corresponding to the value itself, and @var{value-flags} is @samp{*} for -a value which can be dereferenced and @samp{-} for a value which cannot. - -@findex value-begin -@findex value-end -If the value is not added to the value history (it is an invalid float -or it is printed with the @code{output} command), the annotation is similar: - -@example -^Z^Zvalue-begin @var{value-flags} -@var{the-value} -^Z^Zvalue-end -@end example - -@findex arg-begin -@findex arg-name-end -@findex arg-value -@findex arg-end -When GDB prints an argument to a function (for example, in the output -from the @code{backtrace} command), it annotates it as follows: - -@example -^Z^Zarg-begin -@var{argument-name} -^Z^Zarg-name-end -@var{separator-string} -^Z^Zarg-value @var{value-flags} -@var{the-value} -^Z^Zarg-end -@end example - -where @var{argument-name} is the name of the argument, -@var{separator-string} is text which separates the name from the value -for the user's benefit (such as @samp{=}), and @var{value-flags} and -@var{the-value} have the same meanings as in a -@code{value-history-begin} annotation. - -@findex field-begin -@findex field-name-end -@findex field-value -@findex field-end -When printing a structure, GDB annotates it as follows: - -@example -^Z^Zfield-begin @var{value-flags} -@var{field-name} -^Z^Zfield-name-end -@var{separator-string} -^Z^Zfield-value -@var{the-value} -^Z^Zfield-end -@end example - -where @var{field-name} is the name of the field, @var{separator-string} -is text which separates the name from the value for the user's benefit -(such as @samp{=}), and @var{value-flags} and @var{the-value} have the -same meanings as in a @code{value-history-begin} annotation. - -When printing an array, GDB annotates it as follows: - -@example -^Z^Zarray-section-begin @var{array-index} @var{value-flags} -@end example - -where @var{array-index} is the index of the first element being -annotated and @var{value-flags} has the same meaning as in a -@code{value-history-begin} annotation. This is followed by any number -of elements, where is element can be either a single element: - -@findex elt -@example -@samp{,} @var{whitespace} ; @r{omitted for the first element} -@var{the-value} -^Z^Zelt -@end example - -or a repeated element - -@findex elt-rep -@findex elt-rep-end -@example -@samp{,} @var{whitespace} ; @r{omitted for the first element} -@var{the-value} -^Z^Zelt-rep @var{number-of-repititions} -@var{repetition-string} -^Z^Zelt-rep-end -@end example - -In both cases, @var{the-value} is the output for the value of the -element and @var{whitespace} can contain spaces, tabs, and newlines. In -the repeated case, @var{number-of-repititons} is the number of -consecutive array elements which contain that value, and -@var{repetition-string} is a string which is designed to convey to the -user that repitition is being depicted. - -@findex array-section-end -Once all the array elements have been output, the array annotation is -ended with - -@example -^Z^Zarray-section-end -@end example - -@node Frames -@chapter Frames - -Whenever GDB prints a frame, it annotates it. For example, this applies -to frames printed when GDB stops, output from commands such as -@code{backtrace} or @code{up}, etc. - -@findex frame-begin -The frame annotation begins with - -@example -^Z^Zframe-begin @var{level} @var{address} -@var{level-string} -@end example - -where @var{level} is the number of the frame (0 is the innermost frame, -and other frames have positive numbers), @var{address} is the address of -the code executing in that frame, and @var{level-string} is a string -designed to convey the level to the user. The frame ends with - -@findex frame-end -@example -^Z^Zframe-end -@end example - -Between these annotations is the main body of the frame, which can -consist of - -@itemize @bullet -@item -@findex function-call -@example -^Z^Zfunction-call -@var{function-call-string} -@end example - -where @var{function-call-string} is text designed to convey to the user -that this frame is associated with a function call made by GDB to a -function in the program being debugged. - -@item -@findex signal-handler-caller -@example -^Z^Zsignal-handler-caller -@var{signal-handler-caller-string} -@end example - -where @var{signal-handler-caller-string} is text designed to convey to -the user that this frame is associated with whatever mechanism is used -by this operating system to call a signal handler (it is the frame which -calls the signal handler, not the frame for the signal handler itself). - -@item -A normal frame. - -@findex frame-address -@findex frame-address-end -This can optionally (depending on whether this is thought of as -interesting information for the user to see) begin with - -@example -^Z^Zframe-address -@var{address} -^Z^Zframe-address-end -@var{separator-string} -@end example - -where @var{address} is the address executing in the frame (the same -address as in the @code{frame-begin} annotation), and -@var{separator-string} is a string intended to separate this address -from what follows for the user's benefit. - -@findex frame-function-name -@findex frame-args -Then comes - -@example -^Z^Zframe-function-name -@var{function-name} -^Z^Zframe-args -@var{arguments} -@end example - -where @var{function-name} is the name of the function executing in the -frame, or @samp{??} if not known, and @var{arguments} are the arguments -to the frame, with parentheses around them (each argument is annotated -individually as well @pxref{Values}). - -@findex frame-source-begin -@findex frame-source-file -@findex frame-source-file-end -@findex frame-source-line -@findex frame-source-end -If source information is available, a reference to it is then printed: - -@example -^Z^Zframe-source-begin -@var{source-intro-string} -^Z^Zframe-source-file -@var{filename} -^Z^Zframe-source-file-end -: -^Z^Zframe-source-line -@var{line-number} -^Z^Zframe-source-end -@end example - -where @var{source-intro-string} separates for the user's benefit the -reference from the text which precedes it, @var{filename} is the name of -the source file, and @var{line-number} is the line number within that -file (the first line is line 1). - -@findex frame-where -If GDB prints some information about where the frame is from (which -library, which load segment, etc.; currently only done on the RS/6000), -it is annotated with - -@example -^Z^Zframe-where -@var{information} -@end example - -Then, if source is to actually be displayed for this frame (for example, -this is not true for output from the @code{backtrace} command), then a -@code{source} annotation (@pxref{Source}) is displayed. Unlike most -annotations, this is output instead of the normal text which would be -output, not in addition. -@end itemize - -@node Displays -@chapter Displays - -@findex display-begin -@findex display-number-end -@findex display-format -@findex display-expression -@findex display-expression-end -@findex display-value -@findex display-end -When GDB is told to display something using the @code{display} command, -the results of the display are annotated: - -@example -^Z^Zdisplay-begin -@var{number} -^Z^Zdisplay-number-end -@var{number-separator} -^Z^Zdisplay-format -@var{format} -^Z^Zdisplay-expression -@var{expression} -^Z^Zdisplay-expression-end -@var{expression-separator} -^Z^Zdisplay-value -@var{value} -^Z^Zdisplay-end -@end example - -where @var{number} is the number of the display, @var{number-separator} -is intended to separate the number from what follows for the user, -@var{format} includes information such as the size, format, or other -information about how the value is being displayed, @var{expression} is -the expression being displayed, @var{expression-separator} is intended -to separate the expression from the text that follows for the user, -and @var{value} is the actual value being displayed. - -@node Prompting -@chapter Annotation for GDB Input - -When GDB prompts for input, it annotates this fact so it is possible -to know when to send output, when the output from a given command is -over, etc. - -Different kinds of input each have a different @dfn{input type}. Each -input type has three annotations: a @code{pre-} annotation, which -denotes the beginning of any prompt which is being output, a plain -annotation, which denotes the end of the prompt, and then a @code{post-} -annotation which denotes the end of any echo which may (or may not) be -associated with the input. For example, the @code{prompt} input type -features the following annotations: - -@example -^Z^Zpre-prompt -^Z^Zprompt -^Z^Zpost-prompt -@end example - -The input types are - -@table @code -@findex pre-prompt -@findex prompt -@findex post-prompt -@item prompt -When GDB is prompting for a command (the main GDB prompt). - -@findex pre-commands -@findex commands -@findex post-commands -@item commands -When GDB prompts for a set of commands, like in the @code{commands} -command. The annotations are repeated for each command which is input. - -@findex pre-overload-choice -@findex overload-choice -@findex post-overload-choice -@item overload-choice -When GDB wants the user to select between various overloaded functions. - -@findex pre-query -@findex query -@findex post-query -@item query -When GDB wants the user to confirm a potentially dangerous operation. - -@findex pre-prompt-for-continue -@findex prompt-for-continue -@findex post-prompt-for-continue -@item prompt-for-continue -When GDB is asking the user to press return to continue. Note: Don't -expect this to work well; instead use @code{set height 0} to disable -prompting. This is because the counting of lines is buggy in the -presence of annotations. -@end table - -@node Errors -@chapter Errors - -@findex quit -@example -^Z^Zquit -@end example - -This annotation occurs right before GDB responds to an interrupt. - -@findex error -@example -^Z^Zerror -@end example - -This annotation occurs right before GDB responds to an error. - -Quit and error annotations indicate that any annotations which GDB was -in the middle of may end abruptly. For example, if a -@code{value-history-begin} annotation is followed by a @code{error}, one -cannot expect to receive the matching @code{value-history-end}. One -cannot expect not to receive it either, however; an error annotation -does not necessarily mean that GDB is immediately returning all the way -to the top level. - -@findex error-begin -A quit or error annotation may be preceded by - -@example -^Z^Zerror-begin -@end example - -Any output between that and the quit or error annotation is the error -message. - -Warning messages are not yet annotated. -@c If we want to change that, need to fix warning(), type_error(), -@c range_error(), and possibly other places. - -@node Breakpoint Info -@chapter Information on Breakpoints - -The output from the @code{info breakpoints} command is annotated as follows: - -@findex breakpoints-headers -@findex breakpoints-table -@example -^Z^Zbreakpoints-headers -@var{header-entry} -^Z^Zbreakpoints-table -@end example - -where @var{header-entry} has the same syntax as an entry (see below) but -instead of containing data, it contains strings which are intended to -convey the meaning of each field to the user. This is followed by any -number of entries. If a field does not apply for this entry, it is -omitted. Fields may contain trailing whitespace. Each entry consists -of: - -@findex record -@findex field -@example -^Z^Zrecord -^Z^Zfield 0 -@var{number} -^Z^Zfield 1 -@var{type} -^Z^Zfield 2 -@var{disposition} -^Z^Zfield 3 -@var{enable} -^Z^Zfield 4 -@var{address} -^Z^Zfield 5 -@var{what} -^Z^Zfield 6 -@var{frame} -^Z^Zfield 7 -@var{condition} -^Z^Zfield 8 -@var{ignore-count} -^Z^Zfield 9 -@var{commands} -@end example - -The output ends with - -@findex breakpoints-table-end -@example -^Z^Zbreakpoints-table-end -@end example - -@node Invalidation -@chapter Invalidation Notices - -The following annotations say that certain pieces of state may have -changed. - -@table @code -@findex frames-invalid -@item ^Z^Zframes-invalid - -The frames (for example, output from the @code{backtrace} command) may -have changed. - -@findex breakpoints-invalid -@item ^Z^Zbreakpoints-invalid - -The breakpoints may have changed. For example, the user just added or -deleted a breakpoint. -@end table - -@node Running -@chapter Running the Program - -@findex starting -@findex stopping -When the program starts executing due to a GDB command such as -@code{step} or @code{continue}, - -@example -^Z^Zstarting -@end example - -is output. When the program stops, - -@example -^Z^Zstopped -@end example - -is output. Before the @code{stopped} annotation, a variety of -annotations describe how the program stopped. - -@table @code -@findex exited -@item ^Z^Zexited @var{exit-status} -The program exited, and @var{exit-status} is the exit status (zero for -successful exit, otherwise nonzero). - -@findex signalled -@findex signal-name -@findex signal-name-end -@findex signal-string -@findex signal-string-end -@item ^Z^Zsignalled -The program exited with a signal. After the @code{^Z^Zsignalled}, the -annotation continues: - -@example -@var{intro-text} -^Z^Zsignal-name -@var{name} -^Z^Zsignal-name-end -@var{middle-text} -^Z^Zsignal-string -@var{string} -^Z^Zsignal-string-end -@var{end-text} -@end example - -where @var{name} is the name of the signal, such as @code{SIGILL} or -@code{SIGSEGV}, and @var{string} is the explanation of the signal, such -as @code{Illegal Instruction} or @code{Segmentation fault}. -@var{intro-text}, @var{middle-text}, and @var{end-text} are for the -user's benefit and have no particular format. - -@findex signal -@item ^Z^Zsignal -The syntax of this annotation is just like @code{signalled}, but GDB is -just saying that the program received the signal, not that it was -terminated with it. - -@findex breakpoint -@item ^Z^Zbreakpoint @var{number} -The program hit breakpoint number @var{number}. - -@findex watchpoint -@item ^Z^Zwatchpoint @var{number} -The program hit watchpoint number @var{number}. -@end table - -@node Source -@chapter Displaying Source - -@findex source -The following annotation is used instead of displaying source code: - -@example -^Z^Zsource @var{filename}:@var{line}:@var{character}:@var{middle}:@var{addr} -@end example - -where @var{filename} is an absolute file name indicating which source -file, @var{line} is the line number within that file (where 1 is the -first line in the file), @var{character} is the character position -within the file (where 0 is the first character in the file) (for most -debug formats this will necessarily point to the beginning of a line), -@var{middle} is @samp{middle} if @var{addr} is in the middle of the -line, or @samp{beg} if @var{addr} is at the beginning of the line, and -@var{addr} is the address in the target program associated with the -source which is being displayed. - -@node TODO -@chapter Annotations We Might Want in the Future - -@format - - target-invalid - the target might have changed (registers, heap contents, or - execution status). For performance, we might eventually want - to hit `registers-invalid' and `all-registers-invalid' with - greater precision - - - systematic annotation for set/show parameters (including - invalidation notices). - - - similarly, `info' returns a list of candidates for invalidation - notices. -@end format - -@node Index -@unnumbered Index - -@printindex fn - -@bye diff --git a/gnu/usr.bin/gdb/doc/gdb-cfg.texi b/gnu/usr.bin/gdb/doc/gdb-cfg.texi index ec64da1..5b549c2 100644 --- a/gnu/usr.bin/gdb/doc/gdb-cfg.texi +++ b/gnu/usr.bin/gdb/doc/gdb-cfg.texi @@ -87,6 +87,9 @@ @c Discuss gdbserver? @set GDBSERVER @c +@c Discuss gdbserve.nlm? +@set GDBSERVE +@c @c Refrain from discussing how to configure sw and format doc? @clear PRECONFIGURED @c diff --git a/gnu/usr.bin/gdb/doc/gdb.texinfo b/gnu/usr.bin/gdb/doc/gdb.texinfo deleted file mode 100644 index 5db9253..0000000 --- a/gnu/usr.bin/gdb/doc/gdb.texinfo +++ /dev/null @@ -1,8921 +0,0 @@ -\input texinfo @c -*-texinfo-*- -@c Copyright 1988 1989 1990 1991 1992 1993 1994 Free Software Foundation, Inc. -@c -@c %**start of header -@c makeinfo ignores cmds prev to setfilename, so its arg cannot make use -@c of @set vars. However, you can override filename with makeinfo -o. -@setfilename gdb.info -@c -@include gdb-cfg.texi -@c -@ifset GENERIC -@settitle Debugging with @value{GDBN} -@end ifset -@ifclear GENERIC -@settitle Debugging with @value{GDBN} (@value{TARGET}) -@end ifclear -@setchapternewpage odd -@c %**end of header - -@iftex -@c @smallbook -@c @cropmarks -@end iftex - -@finalout -@syncodeindex ky cp - -@c readline appendices use @vindex -@syncodeindex vr cp - -@c !!set GDB manual's edition---not the same as GDB version! -@set EDITION 4.12 - -@c !!set GDB manual's revision date -@set DATE January 1994 - -@c GDB CHANGELOG CONSULTED BETWEEN: -@c Fri Oct 11 23:27:06 1991 John Gilmore (gnu at cygnus.com) -@c Sat Dec 22 02:51:40 1990 John Gilmore (gnu at cygint) - -@c THIS MANUAL REQUIRES TEXINFO-2 macros and info-makers to format properly. - -@ifinfo -@c This is a dir.info fragment to support semi-automated addition of -@c manuals to an info tree. zoo@cygnus.com is developing this facility. -@format -START-INFO-DIR-ENTRY -* Gdb: (gdb). The GNU debugger. -END-INFO-DIR-ENTRY -@end format -@end ifinfo -@c -@c -@ifinfo -This file documents the GNU debugger @value{GDBN}. - - -This is Edition @value{EDITION}, @value{DATE}, -of @cite{Debugging with @value{GDBN}: the GNU Source-Level Debugger} -for GDB Version @value{GDBVN}. - -Copyright (C) 1988, '89, '90, '91, '92, '93 Free Software Foundation, Inc. - -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -@ignore -Permission is granted to process this file through TeX and print the -results, provided the printed document carries copying permission -notice identical to this one except for the removal of this paragraph -(this paragraph not being relevant to the printed manual). - -@end ignore -Permission is granted to copy and distribute modified versions of this -manual under the conditions for verbatim copying, provided also that the -entire resulting derived work is distributed under the terms of a -permission notice identical to this one. - -Permission is granted to copy and distribute translations of this manual -into another language, under the above conditions for modified versions. -@end ifinfo - -@titlepage -@title Debugging with @value{GDBN} -@subtitle The GNU Source-Level Debugger -@ifclear GENERIC -@subtitle (@value{TARGET}) -@end ifclear -@sp 1 -@subtitle Edition @value{EDITION}, for @value{GDBN} version @value{GDBVN} -@subtitle @value{DATE} -@author Richard M. Stallman and Roland H. Pesch -@page -@tex -{\parskip=0pt -\hfill (Send bugs and comments on @value{GDBN} to bug-gdb\@prep.ai.mit.edu.)\par -\hfill {\it Debugging with @value{GDBN}}\par -\hfill \TeX{}info \texinfoversion\par -\hfill pesch\@cygnus.com\par -} -@end tex - -@vskip 0pt plus 1filll -Copyright @copyright{} 1988, '89, '90, '91, '92, '93 Free Software -Foundation, Inc. -@sp 2 -Published by the Free Software Foundation @* -675 Massachusetts Avenue, @* -Cambridge, MA 02139 USA @* -Printed copies are available for $20 each. @* -ISBN 1-882114-11-6 @* - -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -Permission is granted to copy and distribute modified versions of this -manual under the conditions for verbatim copying, provided also that the -entire resulting derived work is distributed under the terms of a -permission notice identical to this one. - -Permission is granted to copy and distribute translations of this manual -into another language, under the above conditions for modified versions. -@end titlepage -@page - -@ifinfo -@node Top -@top Debugging with @value{GDBN} - -This file describes @value{GDBN}, the GNU symbolic debugger. - -This is Edition @value{EDITION}, @value{DATE}, for GDB Version @value{GDBVN}. - -@menu -* Summary:: Summary of @value{GDBN} -@ifset NOVEL -* New Features:: New features since GDB version 3.5 -@end ifset -@ifclear BARETARGET -* Sample Session:: A sample @value{GDBN} session -@end ifclear - -* Invocation:: Getting in and out of @value{GDBN} -* Commands:: @value{GDBN} commands -* Running:: Running programs under @value{GDBN} -* Stopping:: Stopping and continuing -* Stack:: Examining the stack -* Source:: Examining source files -* Data:: Examining data -@ifclear CONLY -* Languages:: Using @value{GDBN} with different languages -@end ifclear -@ifset CONLY -* C:: C language support -@end ifset -@c remnant makeinfo bug, blank line needed after two end-ifs? - -* Symbols:: Examining the symbol table -* Altering:: Altering execution -* GDB Files:: @value{GDBN} files -* Targets:: Specifying a debugging target -* Controlling GDB:: Controlling @value{GDBN} -* Sequences:: Canned sequences of commands -@ifclear DOSHOST -* Emacs:: Using @value{GDBN} under GNU Emacs -@end ifclear - -* GDB Bugs:: Reporting bugs in @value{GDBN} -* Command Line Editing:: Facilities of the readline library -* Using History Interactively:: -@ifset NOVEL -* Renamed Commands:: -@end ifset -@ifclear PRECONFIGURED -* Formatting Documentation:: How to format and print GDB documentation -* Installing GDB:: Installing GDB -@end ifclear - -* Index:: Index -@end menu -@end ifinfo - -@node Summary -@unnumbered Summary of @value{GDBN} - -The purpose of a debugger such as @value{GDBN} is to allow you to see what is -going on ``inside'' another program while it executes---or what another -program was doing at the moment it crashed. - -@value{GDBN} can do four main kinds of things (plus other things in support of -these) to help you catch bugs in the act: - -@itemize @bullet -@item -Start your program, specifying anything that might affect its behavior. - -@item -Make your program stop on specified conditions. - -@item -Examine what has happened, when your program has stopped. - -@item -Change things in your program, so you can experiment with correcting the -effects of one bug and go on to learn about another. -@end itemize - -@ifclear CONLY -You can use @value{GDBN} to debug programs written in C or C++. -@c "MOD2" used as a "miscellaneous languages" flag here. -@c This is acceptable while there is no real doc for Chill and Pascal. -@ifclear MOD2 -For more information, see @ref{Support,,Supported languages}. -@end ifclear -@ifset MOD2 -For more information, see @ref{C,,C and C++}. - -Support for Modula-2 and Chill is partial. For information on Modula-2, -see @ref{Modula-2,,Modula-2}. There is no further documentation on Chill yet. - -Debugging Pascal programs which use sets, subranges, file variables, or nested -functions does not currently work. @value{GDBN} does not support -entering expressions, printing values, or similar features using Pascal syntax. -@end ifset -@ifset FORTRAN -@cindex Fortran -@value{GDBN} can be used to debug programs written in Fortran, although -it does not yet support entering expressions, printing values, or -similar features using Fortran syntax. It may be necessary to refer to -some variables with a trailing underscore. -@end ifset -@end ifclear - -@menu -* Free Software:: Freely redistributable software -* Contributors:: Contributors to GDB -@end menu - -@node Free Software -@unnumberedsec Free software - -@value{GDBN} is @dfn{free software}, protected by the GNU General Public License -(GPL). The GPL gives you the freedom to copy or adapt a licensed -program---but every person getting a copy also gets with it the -freedom to modify that copy (which means that they must get access to -the source code), and the freedom to distribute further copies. -Typical software companies use copyrights to limit your freedoms; the -Free Software Foundation uses the GPL to preserve these freedoms. - -Fundamentally, the General Public License is a license which says that -you have these freedoms and that you cannot take these freedoms away -from anyone else. - -@node Contributors -@unnumberedsec Contributors to GDB - -Richard Stallman was the original author of GDB, and of many other GNU -programs. Many others have contributed to its development. This -section attempts to credit major contributors. One of the virtues of -free software is that everyone is free to contribute to it; with -regret, we cannot actually acknowledge everyone here. The file -@file{ChangeLog} in the GDB distribution approximates a blow-by-blow -account. - -Changes much prior to version 2.0 are lost in the mists of time. - -@quotation -@emph{Plea:} Additions to this section are particularly welcome. If you -or your friends (or enemies, to be evenhanded) have been unfairly -omitted from this list, we would like to add your names! -@end quotation - -So that they may not regard their long labor as thankless, we -particularly thank those who shepherded GDB through major releases: -Fred Fish (releases 4.12, 4.11, 4.10, and 4.9), -Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4), -John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9); -Jim Kingdon (releases 3.5, 3.4, and 3.3); -and Randy Smith (releases 3.2, 3.1, and 3.0). -As major maintainer of GDB for some period, each -contributed significantly to the structure, stability, and capabilities -of the entire debugger. - -Richard Stallman, assisted at various times by Peter TerMaat, Chris -Hanson, and Richard Mlynarik, handled releases through 2.8. - -@ifclear CONLY -Michael Tiemann is the author of most of the GNU C++ support in GDB, -with significant additional contributions from Per Bothner. James -Clark wrote the GNU C++ demangler. Early work on C++ was by Peter -TerMaat (who also did much general update work leading to release 3.0). -@end ifclear - -GDB 4 uses the BFD subroutine library to examine multiple -object-file formats; BFD was a joint project of David V. -Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore. - -David Johnson wrote the original COFF support; Pace Willison did -the original support for encapsulated COFF. - -Adam de Boor and Bradley Davis contributed the ISI Optimum V support. -Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS -support. -Jean-Daniel Fekete contributed Sun 386i support. -Chris Hanson improved the HP9000 support. -Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support. -David Johnson contributed Encore Umax support. -Jyrki Kuoppala contributed Altos 3068 support. -Jeff Law contributed HP PA and SOM support. -Keith Packard contributed NS32K support. -Doug Rabson contributed Acorn Risc Machine support. -Bob Rusk contributed Harris Nighthawk CX-UX support. -Chris Smith contributed Convex support (and Fortran debugging). -Jonathan Stone contributed Pyramid support. -Michael Tiemann contributed SPARC support. -Tim Tucker contributed support for the Gould NP1 and Gould Powernode. -Pace Willison contributed Intel 386 support. -Jay Vosburgh contributed Symmetry support. - -Rich Schaefer and Peter Schauer helped with support of SunOS shared -libraries. - -Jay Fenlason and Roland McGrath ensured that GDB and GAS agree about -several machine instruction sets. - -Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped -develop remote debugging. Intel Corporation and Wind River Systems -contributed remote debugging modules for their products. - -Brian Fox is the author of the readline libraries providing -command-line editing and command history. - -Andrew Beers of SUNY Buffalo wrote the language-switching code, -@ifset MOD2 -the Modula-2 support, -@end ifset -and contributed the Languages chapter of this manual. - -Fred Fish wrote most of the support for Unix System Vr4. -@ifclear CONLY -He also enhanced the command-completion support to cover C++ overloaded -symbols. -@end ifclear - -Hitachi America, Ltd. sponsored the support for Hitachi microprocessors. - -Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware -watchpoints. - -Stu Grossman wrote gdbserver. - -Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made -nearly innumerable bug fixes and cleanups throughout GDB. - -@ifset NOVEL -@node New Features -@unnumbered New Features since GDB Version 3.5 - -@table @emph -@item Targets -Using the new command @code{target}, you can select at runtime whether -you are debugging local files, local processes, standalone systems over -a serial port, or realtime systems over a TCP/IP connection. The -command @code{load} can download programs into a remote system. Serial -stubs are available for Motorola 680x0, Intel 80386, and Sparc remote -systems; GDB also supports debugging realtime processes running under -VxWorks, using SunRPC Remote Procedure Calls over TCP/IP to talk to a -debugger stub on the target system. Internally, GDB now uses a function -vector to mediate access to different targets; if you need to add your -own support for a remote protocol, this makes it much easier. - -@item Watchpoints -GDB now sports watchpoints as well as breakpoints. You can use a -watchpoint to stop execution whenever the value of an expression -changes, without having to predict a particular place in your program -where this may happen. - -@item Wide Output -Commands that issue wide output now insert newlines at places designed -to make the output more readable. - -@item Object Code Formats -GDB uses a new library called the Binary File Descriptor (BFD) Library -to permit it to switch dynamically, without reconfiguration or -recompilation, between different object-file formats. Formats currently -supported are COFF, ELF, a.out, Intel 960 b.out, MIPS ECOFF, HPPA SOM -(with stabs debugging), and S-records; files may be read as .o files, -archive libraries, or core dumps. BFD is available as a subroutine -library so that other programs may take advantage of it, and the other -GNU binary utilities are being converted to use it. - -@item Configuration and Ports -Compile-time configuration (to select a particular architecture and -operating system) is much easier. The script @code{configure} now -allows you to configure GDB as either a native debugger or a -cross-debugger. @xref{Installing GDB}, for details on how to -configure. - -@item Interaction -The user interface to the GDB control variables is simpler, -and is consolidated in two commands, @code{set} and @code{show}. Output -lines are now broken at readable places, rather than overflowing onto -the next line. You can suppress output of machine-level addresses, -displaying only source language information. - -@item C++ -GDB now supports C++ multiple inheritance (if used with a GCC -version 2 compiler), and also has limited support for C++ exception -handling, with the commands @code{catch} and @code{info catch}: GDB -can break when an exception is raised, before the stack is peeled back -to the exception handler's context. - -@ifset MOD2 -@item Modula-2 -GDB now has preliminary support for the GNU Modula-2 compiler, currently -under development at the State University of New York at Buffalo. -Coordinated development of both GDB and the GNU Modula-2 compiler will -continue. Other Modula-2 compilers are currently not supported, and -attempting to debug programs compiled with them will likely result in an -error as the symbol table of the executable is read in. -@end ifset - -@item Command Rationalization -Many GDB commands have been renamed to make them easier to remember -and use. In particular, the subcommands of @code{info} and -@code{show}/@code{set} are grouped to make the former refer to the state -of your program, and the latter refer to the state of GDB itself. -@xref{Renamed Commands}, for details on what commands were renamed. - -@item Shared Libraries -GDB 4 can debug programs and core files that use SunOS, SVR4, or IBM RS/6000 -shared libraries. - -@item Threads -On some systems, GDB 4 has facilities to debug multi-thread programs. - -@item Reference Card -GDB 4 has a reference card. @xref{Formatting Documentation,,Formatting -the Documentation}, for instructions about how to print it. -@end table -@end ifset - -@ifclear BARETARGET -@node Sample Session -@chapter A Sample @value{GDBN} Session - -You can use this manual at your leisure to read all about @value{GDBN}. -However, a handful of commands are enough to get started using the -debugger. This chapter illustrates those commands. - -@iftex -In this sample session, we emphasize user input like this: @b{input}, -to make it easier to pick out from the surrounding output. -@end iftex - -@c FIXME: this example may not be appropriate for some configs, where -@c FIXME...primary interest is in remote use. - -One of the preliminary versions of GNU @code{m4} (a generic macro -processor) exhibits the following bug: sometimes, when we change its -quote strings from the default, the commands used to capture one macro -definition within another stop working. In the following short @code{m4} -session, we define a macro @code{foo} which expands to @code{0000}; we -then use the @code{m4} built-in @code{defn} to define @code{bar} as the -same thing. However, when we change the open quote string to -@code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same -procedure fails to define a new synonym @code{baz}: - -@smallexample -$ @b{cd gnu/m4} -$ @b{./m4} -@b{define(foo,0000)} - -@b{foo} -0000 -@b{define(bar,defn(`foo'))} - -@b{bar} -0000 -@b{changequote(<QUOTE>,<UNQUOTE>)} - -@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} -@b{baz} -@b{C-d} -m4: End of input: 0: fatal error: EOF in string -@end smallexample - -@noindent -Let us use @value{GDBN} to try to see what is going on. - -@smallexample -$ @b{@value{GDBP} m4} -@c FIXME: this falsifies the exact text played out, to permit smallbook -@c FIXME... format to come out better. -GDB is free software and you are welcome to distribute copies - of it under certain conditions; type "show copying" to see - the conditions. -There is absolutely no warranty for GDB; type "show warranty" - for details. -GDB @value{GDBVN}, Copyright 1993 Free Software Foundation, Inc... -(@value{GDBP}) -@end smallexample - -@noindent -@value{GDBN} reads only enough symbol data to know where to find the -rest when needed; as a result, the first prompt comes up very quickly. -We now tell @value{GDBN} to use a narrower display width than usual, so -that examples fit in this manual. - -@smallexample -(@value{GDBP}) @b{set width 70} -@end smallexample - -@noindent -We need to see how the @code{m4} built-in @code{changequote} works. -Having looked at the source, we know the relevant subroutine is -@code{m4_changequote}, so we set a breakpoint there with the @value{GDBN} -@code{break} command. - -@smallexample -(@value{GDBP}) @b{break m4_changequote} -Breakpoint 1 at 0x62f4: file builtin.c, line 879. -@end smallexample - -@noindent -Using the @code{run} command, we start @code{m4} running under @value{GDBN} -control; as long as control does not reach the @code{m4_changequote} -subroutine, the program runs as usual: - -@smallexample -(@value{GDBP}) @b{run} -Starting program: /work/Editorial/gdb/gnu/m4/m4 -@b{define(foo,0000)} - -@b{foo} -0000 -@end smallexample - -@noindent -To trigger the breakpoint, we call @code{changequote}. @value{GDBN} -suspends execution of @code{m4}, displaying information about the -context where it stops. - -@smallexample -@b{changequote(<QUOTE>,<UNQUOTE>)} - -Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) - at builtin.c:879 -879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3)) -@end smallexample - -@noindent -Now we use the command @code{n} (@code{next}) to advance execution to -the next line of the current function. - -@smallexample -(@value{GDBP}) @b{n} -882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\ - : nil, -@end smallexample - -@noindent -@code{set_quotes} looks like a promising subroutine. We can go into it -by using the command @code{s} (@code{step}) instead of @code{next}. -@code{step} goes to the next line to be executed in @emph{any} -subroutine, so it steps into @code{set_quotes}. - -@smallexample -(@value{GDBP}) @b{s} -set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") - at input.c:530 -530 if (lquote != def_lquote) -@end smallexample - -@noindent -The display that shows the subroutine where @code{m4} is now -suspended (and its arguments) is called a stack frame display. It -shows a summary of the stack. We can use the @code{backtrace} -command (which can also be spelled @code{bt}), to see where we are -in the stack as a whole: the @code{backtrace} command displays a -stack frame for each active subroutine. - -@smallexample -(@value{GDBP}) @b{bt} -#0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") - at input.c:530 -#1 0x6344 in m4_changequote (argc=3, argv=0x33c70) - at builtin.c:882 -#2 0x8174 in expand_macro (sym=0x33320) at macro.c:242 -#3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30) - at macro.c:71 -#4 0x79dc in expand_input () at macro.c:40 -#5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195 -@end smallexample - -@noindent -We step through a few more lines to see what happens. The first two -times, we can use @samp{s}; the next two times we use @code{n} to avoid -falling into the @code{xstrdup} subroutine. - -@smallexample -(@value{GDBP}) @b{s} -0x3b5c 532 if (rquote != def_rquote) -(@value{GDBP}) @b{s} -0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \ -def_lquote : xstrdup(lq); -(@value{GDBP}) @b{n} -536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ - : xstrdup(rq); -(@value{GDBP}) @b{n} -538 len_lquote = strlen(rquote); -@end smallexample - -@noindent -The last line displayed looks a little odd; we can examine the variables -@code{lquote} and @code{rquote} to see if they are in fact the new left -and right quotes we specified. We use the command @code{p} -(@code{print}) to see their values. - -@smallexample -(@value{GDBP}) @b{p lquote} -$1 = 0x35d40 "<QUOTE>" -(@value{GDBP}) @b{p rquote} -$2 = 0x35d50 "<UNQUOTE>" -@end smallexample - -@noindent -@code{lquote} and @code{rquote} are indeed the new left and right quotes. -To look at some context, we can display ten lines of source -surrounding the current line with the @code{l} (@code{list}) command. - -@smallexample -(@value{GDBP}) @b{l} -533 xfree(rquote); -534 -535 lquote = (lq == nil || *lq == '\0') ? def_lquote\ - : xstrdup (lq); -536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ - : xstrdup (rq); -537 -538 len_lquote = strlen(rquote); -539 len_rquote = strlen(lquote); -540 @} -541 -542 void -@end smallexample - -@noindent -Let us step past the two lines that set @code{len_lquote} and -@code{len_rquote}, and then examine the values of those variables. - -@smallexample -(@value{GDBP}) @b{n} -539 len_rquote = strlen(lquote); -(@value{GDBP}) @b{n} -540 @} -(@value{GDBP}) @b{p len_lquote} -$3 = 9 -(@value{GDBP}) @b{p len_rquote} -$4 = 7 -@end smallexample - -@noindent -That certainly looks wrong, assuming @code{len_lquote} and -@code{len_rquote} are meant to be the lengths of @code{lquote} and -@code{rquote} respectively. We can set them to better values using -the @code{p} command, since it can print the value of -any expression---and that expression can include subroutine calls and -assignments. - -@smallexample -(@value{GDBP}) @b{p len_lquote=strlen(lquote)} -$5 = 7 -(@value{GDBP}) @b{p len_rquote=strlen(rquote)} -$6 = 9 -@end smallexample - -@noindent -Is that enough to fix the problem of using the new quotes with the -@code{m4} built-in @code{defn}? We can allow @code{m4} to continue -executing with the @code{c} (@code{continue}) command, and then try the -example that caused trouble initially: - -@smallexample -(@value{GDBP}) @b{c} -Continuing. - -@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} - -baz -0000 -@end smallexample - -@noindent -Success! The new quotes now work just as well as the default ones. The -problem seems to have been just the two typos defining the wrong -lengths. We allow @code{m4} exit by giving it an EOF as input: - -@smallexample -@b{C-d} -Program exited normally. -@end smallexample - -@noindent -The message @samp{Program exited normally.} is from @value{GDBN}; it -indicates @code{m4} has finished executing. We can end our @value{GDBN} -session with the @value{GDBN} @code{quit} command. - -@smallexample -(@value{GDBP}) @b{quit} -@end smallexample -@end ifclear - -@node Invocation -@chapter Getting In and Out of @value{GDBN} - -This chapter discusses how to start @value{GDBN}, and how to get out of it. -(The essentials: type @samp{@value{GDBP}} to start GDB, and type @kbd{quit} -or @kbd{C-d} to exit.) - -@menu -* Invoking GDB:: How to start @value{GDBN} -* Quitting GDB:: How to quit @value{GDBN} -* Shell Commands:: How to use shell commands inside @value{GDBN} -@end menu - -@node Invoking GDB -@section Invoking @value{GDBN} - -@ifset H8EXCLUSIVE -For details on starting up @value{GDBP} as a -remote debugger attached to a Hitachi microprocessor, see @ref{Hitachi -Remote,,@value{GDBN} and Hitachi Microprocessors}. -@end ifset - -Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started, -@value{GDBN} reads commands from the terminal until you tell it to exit. - -You can also run @code{@value{GDBP}} with a variety of arguments and options, -to specify more of your debugging environment at the outset. - -@ifset GENERIC -The command-line options described here are designed -to cover a variety of situations; in some environments, some of these -options may effectively be unavailable. -@end ifset - -The most usual way to start @value{GDBN} is with one argument, -specifying an executable program: - -@example -@value{GDBP} @var{program} -@end example - -@ifclear BARETARGET -@noindent -You can also start with both an executable program and a core file -specified: - -@example -@value{GDBP} @var{program} @var{core} -@end example - -You can, instead, specify a process ID as a second argument, if you want -to debug a running process: - -@example -@value{GDBP} @var{program} 1234 -@end example - -@noindent -would attach @value{GDBN} to process @code{1234} (unless you also have a file -named @file{1234}; @value{GDBN} does check for a core file first). - -Taking advantage of the second command-line argument requires a fairly -complete operating system; when you use @value{GDBN} as a remote debugger -attached to a bare board, there may not be any notion of ``process'', -and there is often no way to get a core dump. -@end ifclear - -@noindent -You can further control how @value{GDBN} starts up by using command-line -options. @value{GDBN} itself can remind you of the options available. - -@noindent -Type - -@example -@value{GDBP} -help -@end example - -@noindent -to display all available options and briefly describe their use -(@samp{@value{GDBP} -h} is a shorter equivalent). - -All options and command line arguments you give are processed -in sequential order. The order makes a difference when the -@samp{-x} option is used. - - -@menu -@ifclear GENERIC -@ifset REMOTESTUB -* Remote Serial:: @value{GDBN} remote serial protocol -@end ifset -@ifset I960 -* i960-Nindy Remote:: @value{GDBN} with a remote i960 (Nindy) -@end ifset -@ifset AMD29K -* UDI29K Remote:: The UDI protocol for AMD29K -* EB29K Remote:: The EBMON protocol for AMD29K -@end ifset -@ifset VXWORKS -* VxWorks Remote:: @value{GDBN} and VxWorks -@end ifset -@ifset ST2000 -* ST2000 Remote:: @value{GDBN} with a Tandem ST2000 -@end ifset -@ifset H8 -* Hitachi Remote:: @value{GDBN} and Hitachi Microprocessors -@end ifset -@ifset MIPS -* MIPS Remote:: @value{GDBN} and MIPS boards -@end ifset -@ifset SIMS -* Simulator:: Simulated CPU target -@end ifset -@end ifclear -@c remnant makeinfo bug requires this blank line after *two* end-ifblahs: - -* File Options:: Choosing files -* Mode Options:: Choosing modes -@end menu - -@ifclear GENERIC -@include remote.texi -@end ifclear - -@node File Options -@subsection Choosing files - -@ifclear BARETARGET -When @value{GDBN} starts, it reads any arguments other than options as -specifying an executable file and core file (or process ID). This is -the same as if the arguments were specified by the @samp{-se} and -@samp{-c} options respectively. (@value{GDBN} reads the first argument -that does not have an associated option flag as equivalent to the -@samp{-se} option followed by that argument; and the second argument -that does not have an associated option flag, if any, as equivalent to -the @samp{-c} option followed by that argument.) -@end ifclear -@ifset BARETARGET -When @value{GDBN} starts, it reads any argument other than options as -specifying an executable file. This is the same as if the argument was -specified by the @samp{-se} option. -@end ifset - -Many options have both long and short forms; both are shown in the -following list. @value{GDBN} also recognizes the long forms if you truncate -them, so long as enough of the option is present to be unambiguous. -(If you prefer, you can flag option arguments with @samp{--} rather -than @samp{-}, though we illustrate the more usual convention.) - -@table @code -@item -symbols @var{file} -@itemx -s @var{file} -Read symbol table from file @var{file}. - -@item -exec @var{file} -@itemx -e @var{file} -Use file @var{file} as the executable file to execute when -@ifset BARETARGET -appropriate. -@end ifset -@ifclear BARETARGET -appropriate, and for examining pure data in conjunction with a core -dump. -@end ifclear - -@item -se @var{file} -Read symbol table from file @var{file} and use it as the executable -file. - -@ifclear BARETARGET -@item -core @var{file} -@itemx -c @var{file} -Use file @var{file} as a core dump to examine. - -@item -c @var{number} -Connect to process ID @var{number}, as with the @code{attach} command -(unless there is a file in core-dump format named @var{number}, in which -case @samp{-c} specifies that file as a core dump to read). -@end ifclear - -@item -command @var{file} -@itemx -x @var{file} -Execute @value{GDBN} commands from file @var{file}. @xref{Command -Files,, Command files}. - -@item -directory @var{directory} -@itemx -d @var{directory} -Add @var{directory} to the path to search for source files. - -@ifclear BARETARGET -@item -m -@itemx -mapped -@emph{Warning: this option depends on operating system facilities that are not -supported on all systems.}@* -If memory-mapped files are available on your system through the @code{mmap} -system call, you can use this option -to have @value{GDBN} write the symbols from your -program into a reusable file in the current directory. If the program you are debugging is -called @file{/tmp/fred}, the mapped symbol file is @file{./fred.syms}. -Future @value{GDBN} debugging sessions notice the presence of this file, -and can quickly map in symbol information from it, rather than reading -the symbol table from the executable program. - -@c FIXME! Really host, not target? -The @file{.syms} file is specific to the host machine where @value{GDBN} -is run. It holds an exact image of the internal @value{GDBN} symbol -table. It cannot be shared across multiple host platforms. -@end ifclear - -@item -r -@itemx -readnow -Read each symbol file's entire symbol table immediately, rather than -the default, which is to read it incrementally as it is needed. -This makes startup slower, but makes future operations faster. -@end table - -@ifclear BARETARGET -The @code{-mapped} and @code{-readnow} options are typically combined in -order to build a @file{.syms} file that contains complete symbol -information. (@xref{Files,,Commands to specify files}, for information -on @file{.syms} files.) A simple GDB invocation to do nothing but build -a @file{.syms} file for future use is: - -@example - gdb -batch -nx -mapped -readnow programname -@end example -@end ifclear - -@node Mode Options -@subsection Choosing modes - -You can run @value{GDBN} in various alternative modes---for example, in -batch mode or quiet mode. - -@table @code -@item -nx -@itemx -n -Do not execute commands from any initialization files (normally called -@file{@value{GDBINIT}}). Normally, the commands in these files are -executed after all the command options and arguments have been -processed. @xref{Command Files,,Command files}. - -@item -quiet -@itemx -q -``Quiet''. Do not print the introductory and copyright messages. These -messages are also suppressed in batch mode. - -@item -batch -Run in batch mode. Exit with status @code{0} after processing all the -command files specified with @samp{-x} (and all commands from -initialization files, if not inhibited with @samp{-n}). Exit with -nonzero status if an error occurs in executing the @value{GDBN} commands -in the command files. - -Batch mode may be useful for running @value{GDBN} as a filter, for example to -download and run a program on another computer; in order to make this -more useful, the message - -@example -Program exited normally. -@end example - -@noindent -(which is ordinarily issued whenever a program running under @value{GDBN} control -terminates) is not issued when running in batch mode. - -@item -cd @var{directory} -Run @value{GDBN} using @var{directory} as its working directory, -instead of the current directory. - -@ifset LUCID -@item -context @var{authentication} -When the Energize programming system starts up @value{GDBN}, it uses this -option to trigger an alternate mode of interaction. -@var{authentication} is a pair of numeric codes that identify @value{GDBN} -as a client in the Energize environment. Avoid this option when you run -@value{GDBN} directly from the command line. See @ref{Energize,,Using -@value{GDBN} with Energize} for more discussion of using @value{GDBN} with Energize. -@end ifset - -@ifclear DOSHOST -@item -fullname -@itemx -f -Emacs sets this option when it runs @value{GDBN} as a subprocess. It tells @value{GDBN} -to output the full file name and line number in a standard, -recognizable fashion each time a stack frame is displayed (which -includes each time your program stops). This recognizable format looks -like two @samp{\032} characters, followed by the file name, line number -and character position separated by colons, and a newline. The -Emacs-to-@value{GDBN} interface program uses the two @samp{\032} characters as -a signal to display the source code for the frame. -@end ifclear - -@ifset SERIAL -@item -b @var{bps} -Set the line speed (baud rate or bits per second) of any serial -interface used by @value{GDBN} for remote debugging. - -@item -tty @var{device} -Run using @var{device} for your program's standard input and output. -@c FIXME: kingdon thinks there is more to -tty. Investigate. -@end ifset -@end table - -@node Quitting GDB -@section Quitting @value{GDBN} -@cindex exiting @value{GDBN} -@cindex leaving @value{GDBN} - -@table @code -@item quit -@kindex quit -@kindex q -To exit @value{GDBN}, use the @code{quit} command (abbreviated @code{q}), or type -an end-of-file character (usually @kbd{C-d}). -@end table - -@cindex interrupt -An interrupt (often @kbd{C-c}) does not exit from @value{GDBN}, but rather -terminates the action of any @value{GDBN} command that is in progress and -returns to @value{GDBN} command level. It is safe to type the interrupt -character at any time because @value{GDBN} does not allow it to take effect -until a time when it is safe. - -@ifclear BARETARGET -If you have been using @value{GDBN} to control an attached process or -device, you can release it with the @code{detach} command -(@pxref{Attach, ,Debugging an already-running process}). -@end ifclear - -@node Shell Commands -@section Shell commands - -If you need to execute occasional shell commands during your -debugging session, there is no need to leave or suspend @value{GDBN}; you can -just use the @code{shell} command. - -@table @code -@item shell @var{command string} -@kindex shell -@cindex shell escape -Invoke a the standard shell to execute @var{command string}. -@ifclear DOSHOST -If it exists, the environment variable @code{SHELL} determines which -shell to run. Otherwise @value{GDBN} uses @code{/bin/sh}. -@end ifclear -@end table - -The utility @code{make} is often needed in development environments. -You do not have to use the @code{shell} command for this purpose in -@value{GDBN}: - -@table @code -@item make @var{make-args} -@kindex make -@cindex calling make -Execute the @code{make} program with the specified -arguments. This is equivalent to @samp{shell make @var{make-args}}. -@end table - -@node Commands -@chapter @value{GDBN} Commands - -You can abbreviate a @value{GDBN} command to the first few letters of the command -name, if that abbreviation is unambiguous; and you can repeat certain -@value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB} -key to get @value{GDBN} to fill out the rest of a word in a command (or to -show you the alternatives available, if there is more than one possibility). - -@menu -* Command Syntax:: How to give commands to @value{GDBN} -* Completion:: Command completion -* Help:: How to ask @value{GDBN} for help -@end menu - -@node Command Syntax -@section Command syntax - -A @value{GDBN} command is a single line of input. There is no limit on -how long it can be. It starts with a command name, which is followed by -arguments whose meaning depends on the command name. For example, the -command @code{step} accepts an argument which is the number of times to -step, as in @samp{step 5}. You can also use the @code{step} command -with no arguments. Some command names do not allow any arguments. - -@cindex abbreviation -@value{GDBN} command names may always be truncated if that abbreviation is -unambiguous. Other possible command abbreviations are listed in the -documentation for individual commands. In some cases, even ambiguous -abbreviations are allowed; for example, @code{s} is specially defined as -equivalent to @code{step} even though there are other commands whose -names start with @code{s}. You can test abbreviations by using them as -arguments to the @code{help} command. - -@cindex repeating commands -@kindex RET -A blank line as input to @value{GDBN} (typing just @key{RET}) means to -repeat the previous command. Certain commands (for example, @code{run}) -will not repeat this way; these are commands whose unintentional -repetition might cause trouble and which you are unlikely to want to -repeat. - -The @code{list} and @code{x} commands, when you repeat them with -@key{RET}, construct new arguments rather than repeating -exactly as typed. This permits easy scanning of source or memory. - -@value{GDBN} can also use @key{RET} in another way: to partition lengthy -output, in a way similar to the common utility @code{more} -(@pxref{Screen Size,,Screen size}). Since it is easy to press one -@key{RET} too many in this situation, @value{GDBN} disables command -repetition after any command that generates this sort of display. - -@kindex # -@cindex comment -Any text from a @kbd{#} to the end of the line is a comment; it does -nothing. This is useful mainly in command files (@pxref{Command -Files,,Command files}). - -@node Completion -@section Command completion - -@cindex completion -@cindex word completion -@value{GDBN} can fill in the rest of a word in a command for you, if there is -only one possibility; it can also show you what the valid possibilities -are for the next word in a command, at any time. This works for @value{GDBN} -commands, @value{GDBN} subcommands, and the names of symbols in your program. - -Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest -of a word. If there is only one possibility, @value{GDBN} fills in the -word, and waits for you to finish the command (or press @key{RET} to -enter it). For example, if you type - -@c FIXME "@key" does not distinguish its argument sufficiently to permit -@c complete accuracy in these examples; space introduced for clarity. -@c If texinfo enhancements make it unnecessary, it would be nice to -@c replace " @key" by "@key" in the following... -@example -(@value{GDBP}) info bre @key{TAB} -@end example - -@noindent -@value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is -the only @code{info} subcommand beginning with @samp{bre}: - -@example -(@value{GDBP}) info breakpoints -@end example - -@noindent -You can either press @key{RET} at this point, to run the @code{info -breakpoints} command, or backspace and enter something else, if -@samp{breakpoints} does not look like the command you expected. (If you -were sure you wanted @code{info breakpoints} in the first place, you -might as well just type @key{RET} immediately after @samp{info bre}, -to exploit command abbreviations rather than command completion). - -If there is more than one possibility for the next word when you press -@key{TAB}, @value{GDBN} sounds a bell. You can either supply more -characters and try again, or just press @key{TAB} a second time; -@value{GDBN} displays all the possible completions for that word. For -example, you might want to set a breakpoint on a subroutine whose name -begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN} -just sounds the bell. Typing @key{TAB} again displays all the -function names in your program that begin with those characters, for -example: - -@example -(@value{GDBP}) b make_ @key{TAB} -@exdent @value{GDBN} sounds bell; press @key{TAB} again, to see: -make_a_section_from_file make_environ -make_abs_section make_function_type -make_blockvector make_pointer_type -make_cleanup make_reference_type -make_command make_symbol_completion_list -(@value{GDBP}) b make_ -@end example - -@noindent -After displaying the available possibilities, @value{GDBN} copies your -partial input (@samp{b make_} in the example) so you can finish the -command. - -If you just want to see the list of alternatives in the first place, you -can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?} -means @kbd{@key{META} ?}. You can type this -@ifclear DOSHOST -either by holding down a -key designated as the @key{META} shift on your keyboard (if there is -one) while typing @kbd{?}, or -@end ifclear -as @key{ESC} followed by @kbd{?}. - -@cindex quotes in commands -@cindex completion of quoted strings -Sometimes the string you need, while logically a ``word'', may contain -parentheses or other characters that @value{GDBN} normally excludes from its -notion of a word. To permit word completion to work in this situation, -you may enclose words in @code{'} (single quote marks) in @value{GDBN} commands. - -@ifclear CONLY -The most likely situation where you might need this is in typing the -name of a C++ function. This is because C++ allows function overloading -(multiple definitions of the same function, distinguished by argument -type). For example, when you want to set a breakpoint you may need to -distinguish whether you mean the version of @code{name} that takes an -@code{int} parameter, @code{name(int)}, or the version that takes a -@code{float} parameter, @code{name(float)}. To use the word-completion -facilities in this situation, type a single quote @code{'} at the -beginning of the function name. This alerts @value{GDBN} that it may need to -consider more information than usual when you press @key{TAB} or -@kbd{M-?} to request word completion: - -@example -(@value{GDBP}) b 'bubble( @key{M-?} -bubble(double,double) bubble(int,int) -(@value{GDBP}) b 'bubble( -@end example - -In some cases, @value{GDBN} can tell that completing a name requires using -quotes. When this happens, @value{GDBN} inserts the quote for you (while -completing as much as it can) if you do not type the quote in the first -place: - -@example -(@value{GDBP}) b bub @key{TAB} -@exdent @value{GDBN} alters your input line to the following, and rings a bell: -(@value{GDBP}) b 'bubble( -@end example - -@noindent -In general, @value{GDBN} can tell that a quote is needed (and inserts it) if -you have not yet started typing the argument list when you ask for -completion on an overloaded symbol. -@end ifclear - - -@node Help -@section Getting help -@cindex online documentation -@kindex help - -You can always ask @value{GDBN} itself for information on its commands, using the -command @code{help}. - -@table @code -@item help -@itemx h -@kindex h -You can use @code{help} (abbreviated @code{h}) with no arguments to -display a short list of named classes of commands: - -@smallexample -(@value{GDBP}) help -List of classes of commands: - -running -- Running the program -stack -- Examining the stack -data -- Examining data -breakpoints -- Making program stop at certain points -files -- Specifying and examining files -status -- Status inquiries -support -- Support facilities -user-defined -- User-defined commands -aliases -- Aliases of other commands -obscure -- Obscure features - -Type "help" followed by a class name for a list of -commands in that class. -Type "help" followed by command name for full -documentation. -Command name abbreviations are allowed if unambiguous. -(@value{GDBP}) -@end smallexample - -@item help @var{class} -Using one of the general help classes as an argument, you can get a -list of the individual commands in that class. For example, here is the -help display for the class @code{status}: - -@smallexample -(@value{GDBP}) help status -Status inquiries. - -List of commands: - -@c Line break in "show" line falsifies real output, but needed -@c to fit in smallbook page size. -show -- Generic command for showing things set - with "set" -info -- Generic command for printing status - -Type "help" followed by command name for full -documentation. -Command name abbreviations are allowed if unambiguous. -(@value{GDBP}) -@end smallexample - -@item help @var{command} -With a command name as @code{help} argument, @value{GDBN} displays a -short paragraph on how to use that command. -@end table - -In addition to @code{help}, you can use the @value{GDBN} commands @code{info} -and @code{show} to inquire about the state of your program, or the state -of @value{GDBN} itself. Each command supports many topics of inquiry; this -manual introduces each of them in the appropriate context. The listings -under @code{info} and under @code{show} in the Index point to -all the sub-commands. @xref{Index}. - -@c @group -@table @code -@item info -@kindex info -@kindex i -This command (abbreviated @code{i}) is for describing the state of your -program. For example, you can list the arguments given to your program -with @code{info args}, list the registers currently in use with @code{info -registers}, or list the breakpoints you have set with @code{info breakpoints}. -You can get a complete list of the @code{info} sub-commands with -@w{@code{help info}}. - -@kindex show -@item show -In contrast, @code{show} is for describing the state of @value{GDBN} itself. -You can change most of the things you can @code{show}, by using the -related command @code{set}; for example, you can control what number -system is used for displays with @code{set radix}, or simply inquire -which is currently in use with @code{show radix}. - -@kindex info set -To display all the settable parameters and their current -values, you can use @code{show} with no arguments; you may also use -@code{info set}. Both commands produce the same display. -@c FIXME: "info set" violates the rule that "info" is for state of -@c FIXME...program. Ck w/ GNU: "info set" to be called something else, -@c FIXME...or change desc of rule---eg "state of prog and debugging session"? -@end table -@c @end group - -Here are three miscellaneous @code{show} subcommands, all of which are -exceptional in lacking corresponding @code{set} commands: - -@table @code -@kindex show version -@cindex version number -@item show version -Show what version of @value{GDBN} is running. You should include this -information in @value{GDBN} bug-reports. If multiple versions of @value{GDBN} are in -use at your site, you may occasionally want to determine which version -of @value{GDBN} you are running; as @value{GDBN} evolves, new commands are introduced, -and old ones may wither away. The version number is also announced -when you start @value{GDBN}. - -@kindex show copying -@item show copying -Display information about permission for copying @value{GDBN}. - -@kindex show warranty -@item show warranty -Display the GNU ``NO WARRANTY'' statement. -@end table - -@node Running -@chapter Running Programs Under @value{GDBN} - -When you run a program under @value{GDBN}, you must first generate -debugging information when you compile it. -@ifclear BARETARGET -You may start it with its arguments, if any, in an environment of your -choice. You may redirect your program's input and output, debug an -already running process, or kill a child process. -@end ifclear - -@menu -* Compilation:: Compiling for debugging -* Starting:: Starting your program -@ifclear BARETARGET -* Arguments:: Your program's arguments -* Environment:: Your program's environment -* Working Directory:: Your program's working directory -* Input/Output:: Your program's input and output -* Attach:: Debugging an already-running process -* Kill Process:: Killing the child process -* Process Information:: Additional process information -* Threads:: Debugging programs with multiple threads -@end ifclear -@end menu - -@node Compilation -@section Compiling for debugging - -In order to debug a program effectively, you need to generate -debugging information when you compile it. This debugging information -is stored in the object file; it describes the data type of each -variable or function and the correspondence between source line numbers -and addresses in the executable code. - -To request debugging information, specify the @samp{-g} option when you run -the compiler. - -Many C compilers are unable to handle the @samp{-g} and @samp{-O} -options together. Using those compilers, you cannot generate optimized -executables containing debugging information. - -@value{NGCC}, the GNU C compiler, supports @samp{-g} with or without -@samp{-O}, making it possible to debug optimized code. We recommend -that you @emph{always} use @samp{-g} whenever you compile a program. -You may think your program is correct, but there is no sense in pushing -your luck. - -@cindex optimized code, debugging -@cindex debugging optimized code -When you debug a program compiled with @samp{-g -O}, remember that the -optimizer is rearranging your code; the debugger shows you what is -really there. Do not be too surprised when the execution path does not -exactly match your source file! An extreme example: if you define a -variable, but never use it, @value{GDBN} never sees that -variable---because the compiler optimizes it out of existence. - -Some things do not work as well with @samp{-g -O} as with just -@samp{-g}, particularly on machines with instruction scheduling. If in -doubt, recompile with @samp{-g} alone, and if this fixes the problem, -please report it as a bug (including a test case!). - -Older versions of the GNU C compiler permitted a variant option -@w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this -format; if your GNU C compiler has this option, do not use it. - -@need 2000 -@node Starting -@section Starting your program -@cindex starting -@cindex running - -@table @code -@item run -@itemx r -@kindex run -Use the @code{run} command to start your program under @value{GDBN}. You must -first specify the program name -@ifset VXWORKS -(except on VxWorks) -@end ifset -with an argument to @value{GDBN} (@pxref{Invocation, ,Getting In and -Out of @value{GDBN}}), or by using the @code{file} or @code{exec-file} -command (@pxref{Files, ,Commands to specify files}). - -@end table - -@ifclear BARETARGET -If you are running your program in an execution environment that -supports processes, @code{run} creates an inferior process and makes -that process run your program. (In environments without processes, -@code{run} jumps to the start of your program.) - -The execution of a program is affected by certain information it -receives from its superior. @value{GDBN} provides ways to specify this -information, which you must do @emph{before} starting your program. (You -can change it after starting your program, but such changes only affect -your program the next time you start it.) This information may be -divided into four categories: - -@table @asis -@item The @emph{arguments.} -Specify the arguments to give your program as the arguments of the -@code{run} command. If a shell is available on your target, the shell -is used to pass the arguments, so that you may use normal conventions -(such as wildcard expansion or variable substitution) in describing -the arguments. In Unix systems, you can control which shell is used -with the @code{SHELL} environment variable. @xref{Arguments, ,Your -program's arguments}. - -@item The @emph{environment.} -Your program normally inherits its environment from @value{GDBN}, but you can -use the @value{GDBN} commands @code{set environment} and @code{unset -environment} to change parts of the environment that affect -your program. @xref{Environment, ,Your program's environment}. - -@item The @emph{working directory.} -Your program inherits its working directory from @value{GDBN}. You can set -the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}. -@xref{Working Directory, ,Your program's working directory}. - -@item The @emph{standard input and output.} -Your program normally uses the same device for standard input and -standard output as @value{GDBN} is using. You can redirect input and output -in the @code{run} command line, or you can use the @code{tty} command to -set a different device for your program. -@xref{Input/Output, ,Your program's input and output}. - -@cindex pipes -@emph{Warning:} While input and output redirection work, you cannot use -pipes to pass the output of the program you are debugging to another -program; if you attempt this, @value{GDBN} is likely to wind up debugging the -wrong program. -@end table -@end ifclear - -When you issue the @code{run} command, your program begins to execute -immediately. @xref{Stopping, ,Stopping and continuing}, for discussion -of how to arrange for your program to stop. Once your program has -stopped, you may call functions in your program, using the @code{print} -or @code{call} commands. @xref{Data, ,Examining Data}. - -If the modification time of your symbol file has changed since the last -time @value{GDBN} read its symbols, @value{GDBN} discards its symbol -table, and reads it again. When it does this, @value{GDBN} tries to retain -your current breakpoints. - -@ifclear BARETARGET -@node Arguments -@section Your program's arguments - -@cindex arguments (to your program) -The arguments to your program can be specified by the arguments of the -@code{run} command. They are passed to a shell, which expands wildcard -characters and performs redirection of I/O, and thence to your program. -Your @code{SHELL} environment variable (if it exists) specifies what -shell @value{GDBN} uses. If you do not define @code{SHELL}, -@value{GDBN} uses @code{/bin/sh}. - -@code{run} with no arguments uses the same arguments used by the previous -@code{run}, or those set by the @code{set args} command. - -@kindex set args -@table @code -@item set args -Specify the arguments to be used the next time your program is run. If -@code{set args} has no arguments, @code{run} executes your program -with no arguments. Once you have run your program with arguments, -using @code{set args} before the next @code{run} is the only way to run -it again without arguments. - -@item show args -@kindex show args -Show the arguments to give your program when it is started. -@end table - -@node Environment -@section Your program's environment - -@cindex environment (of your program) -The @dfn{environment} consists of a set of environment variables and -their values. Environment variables conventionally record such things as -your user name, your home directory, your terminal type, and your search -path for programs to run. Usually you set up environment variables with -the shell and they are inherited by all the other programs you run. When -debugging, it can be useful to try running your program with a modified -environment without having to start @value{GDBN} over again. - -@table @code -@item path @var{directory} -@kindex path -Add @var{directory} to the front of the @code{PATH} environment variable -(the search path for executables), for both @value{GDBN} and your program. -You may specify several directory names, separated by @samp{:} or -whitespace. If @var{directory} is already in the path, it is moved to -the front, so it is searched sooner. - -You can use the string @samp{$cwd} to refer to whatever is the current -working directory at the time @value{GDBN} searches the path. If you -use @samp{.} instead, it refers to the directory where you executed the -@code{path} command. @value{GDBN} replaces @samp{.} in the -@var{directory} argument (with the current path) before adding -@var{directory} to the search path. -@c 'path' is explicitly nonrepeatable, but RMS points out it is silly to -@c document that, since repeating it would be a no-op. - -@item show paths -@kindex show paths -Display the list of search paths for executables (the @code{PATH} -environment variable). - -@item show environment @r{[}@var{varname}@r{]} -@kindex show environment -Print the value of environment variable @var{varname} to be given to -your program when it starts. If you do not supply @var{varname}, -print the names and values of all environment variables to be given to -your program. You can abbreviate @code{environment} as @code{env}. - -@item set environment @var{varname} @r{[}=@r{]} @var{value} -@kindex set environment -Set environment variable @var{varname} to @var{value}. The value -changes for your program only, not for @value{GDBN} itself. @var{value} may -be any string; the values of environment variables are just strings, and -any interpretation is supplied by your program itself. The @var{value} -parameter is optional; if it is eliminated, the variable is set to a -null value. -@c "any string" here does not include leading, trailing -@c blanks. Gnu asks: does anyone care? - -For example, this command: - -@example -set env USER = foo -@end example - -@noindent -tells a Unix program, when subsequently run, that its user is named -@samp{foo}. (The spaces around @samp{=} are used for clarity here; they -are not actually required.) - -@item unset environment @var{varname} -@kindex unset environment -Remove variable @var{varname} from the environment to be passed to your -program. This is different from @samp{set env @var{varname} =}; -@code{unset environment} removes the variable from the environment, -rather than assigning it an empty value. -@end table - -@emph{Warning:} @value{GDBN} runs your program using the shell indicated -by your @code{SHELL} environment variable if it exists (or -@code{/bin/sh} if not). If your @code{SHELL} variable names a shell -that runs an initialization file---such as @file{.cshrc} for C-shell, or -@file{.bashrc} for BASH---any variables you set in that file affect -your program. You may wish to move setting of environment variables to -files that are only run when you sign on, such as @file{.login} or -@file{.profile}. - -@node Working Directory -@section Your program's working directory - -@cindex working directory (of your program) -Each time you start your program with @code{run}, it inherits its -working directory from the current working directory of @value{GDBN}. -The @value{GDBN} working directory is initially whatever it inherited -from its parent process (typically the shell), but you can specify a new -working directory in @value{GDBN} with the @code{cd} command. - -The @value{GDBN} working directory also serves as a default for the commands -that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to -specify files}. - -@table @code -@item cd @var{directory} -@kindex cd -Set the @value{GDBN} working directory to @var{directory}. - -@item pwd -@kindex pwd -Print the @value{GDBN} working directory. -@end table - -@node Input/Output -@section Your program's input and output - -@cindex redirection -@cindex i/o -@cindex terminal -By default, the program you run under @value{GDBN} does input and output to -the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal to -its own terminal modes to interact with you, but it records the terminal -modes your program was using and switches back to them when you continue -running your program. - -@table @code -@item info terminal -@kindex info terminal -Displays information recorded by @value{GDBN} about the terminal modes your -program is using. -@end table - -You can redirect your program's input and/or output using shell -redirection with the @code{run} command. For example, - -@example -run > outfile -@end example - -@noindent -starts your program, diverting its output to the file @file{outfile}. - -@kindex tty -@cindex controlling terminal -Another way to specify where your program should do input and output is -with the @code{tty} command. This command accepts a file name as -argument, and causes this file to be the default for future @code{run} -commands. It also resets the controlling terminal for the child -process, for future @code{run} commands. For example, - -@example -tty /dev/ttyb -@end example - -@noindent -directs that processes started with subsequent @code{run} commands -default to do input and output on the terminal @file{/dev/ttyb} and have -that as their controlling terminal. - -An explicit redirection in @code{run} overrides the @code{tty} command's -effect on the input/output device, but not its effect on the controlling -terminal. - -When you use the @code{tty} command or redirect input in the @code{run} -command, only the input @emph{for your program} is affected. The input -for @value{GDBN} still comes from your terminal. - -@node Attach -@section Debugging an already-running process -@kindex attach -@cindex attach - -@table @code -@item attach @var{process-id} -This command attaches to a running process---one that was started -outside @value{GDBN}. (@code{info files} shows your active -targets.) The command takes as argument a process ID. The usual way to -find out the process-id of a Unix process is with the @code{ps} utility, -or with the @samp{jobs -l} shell command. - -@code{attach} does not repeat if you press @key{RET} a second time after -executing the command. -@end table - -To use @code{attach}, your program must be running in an environment -which supports processes; for example, @code{attach} does not work for -programs on bare-board targets that lack an operating system. You must -also have permission to send the process a signal. - -When using @code{attach}, you should first use the @code{file} command -to specify the program running in the process and load its symbol table. -@xref{Files, ,Commands to Specify Files}. - -The first thing @value{GDBN} does after arranging to debug the specified -process is to stop it. You can examine and modify an attached process -with all the @value{GDBN} commands that are ordinarily available when you start -processes with @code{run}. You can insert breakpoints; you can step and -continue; you can modify storage. If you would rather the process -continue running, you may use the @code{continue} command after -attaching @value{GDBN} to the process. - -@table @code -@item detach -@kindex detach -When you have finished debugging the attached process, you can use the -@code{detach} command to release it from @value{GDBN} control. Detaching -the process continues its execution. After the @code{detach} command, -that process and @value{GDBN} become completely independent once more, and you -are ready to @code{attach} another process or start one with @code{run}. -@code{detach} does not repeat if you press @key{RET} again after -executing the command. -@end table - -If you exit @value{GDBN} or use the @code{run} command while you have an -attached process, you kill that process. By default, @value{GDBN} asks -for confirmation if you try to do either of these things; you can -control whether or not you need to confirm by using the @code{set -confirm} command (@pxref{Messages/Warnings, ,Optional warnings and -messages}). - -@node Kill Process -@c @group -@section Killing the child process - -@table @code -@item kill -@kindex kill -Kill the child process in which your program is running under @value{GDBN}. -@end table - -This command is useful if you wish to debug a core dump instead of a -running process. @value{GDBN} ignores any core dump file while your program -is running. -@c @end group - -On some operating systems, a program cannot be executed outside @value{GDBN} -while you have breakpoints set on it inside @value{GDBN}. You can use the -@code{kill} command in this situation to permit running your program -outside the debugger. - -The @code{kill} command is also useful if you wish to recompile and -relink your program, since on many systems it is impossible to modify an -executable file while it is running in a process. In this case, when you -next type @code{run}, @value{GDBN} notices that the file has changed, and -reads the symbol table again (while trying to preserve your current -breakpoint settings). - -@node Process Information -@section Additional process information - -@kindex /proc -@cindex process image -Some operating systems provide a facility called @samp{/proc} that can -be used to examine the image of a running process using file-system -subroutines. If @value{GDBN} is configured for an operating system with this -facility, the command @code{info proc} is available to report on several -kinds of information about the process running your program. - -@table @code -@item info proc -@kindex info proc -Summarize available information about the process. - -@item info proc mappings -@kindex info proc mappings -Report on the address ranges accessible in the program, with information -on whether your program may read, write, or execute each range. - -@item info proc times -@kindex info proc times -Starting time, user CPU time, and system CPU time for your program and -its children. - -@item info proc id -@kindex info proc id -Report on the process IDs related to your program: its own process ID, -the ID of its parent, the process group ID, and the session ID. - -@item info proc status -@kindex info proc status -General information on the state of the process. If the process is -stopped, this report includes the reason for stopping, and any signal -received. - -@item info proc all -Show all the above information about the process. -@end table - -@node Threads -@section Debugging programs with multiple threads - -@cindex threads of execution -@cindex multiple threads -@cindex switching threads -In some operating systems, a single program may have more than one -@dfn{thread} of execution. The precise semantics of threads differ from -one operating system to another, but in general the threads of a single -program are akin to multiple processes---except that they share one -address space (that is, they can all examine and modify the same -variables). On the other hand, each thread has its own registers and -execution stack, and perhaps private memory. - -@value{GDBN} provides these facilities for debugging multi-thread -programs: - -@itemize @bullet -@item automatic notification of new threads -@item @samp{thread @var{threadno}}, a command to switch among threads -@item @samp{info threads}, a command to inquire about existing threads -@item thread-specific breakpoints -@end itemize - -@quotation -@emph{Warning:} These facilities are not yet available on every -@value{GDBN} configuration where the operating system supports threads. -If your @value{GDBN} does not support threads, these commands have no -effect. For example, a system without thread support shows no output -from @samp{info threads}, and always rejects the @code{thread} command, -like this: - -@smallexample -(@value{GDBP}) info threads -(@value{GDBP}) thread 1 -Thread ID 1 not known. Use the "info threads" command to -see the IDs of currently known threads. -@end smallexample -@c FIXME to implementors: how hard would it be to say "sorry, this GDB -@c doesn't support threads"? -@end quotation - -@cindex focus of debugging -@cindex current thread -The @value{GDBN} thread debugging facility allows you to observe all -threads while your program runs---but whenever @value{GDBN} takes -control, one thread in particular is always the focus of debugging. -This thread is called the @dfn{current thread}. Debugging commands show -program information from the perspective of the current thread. - -@kindex New @var{systag} -@cindex thread identifier (system) -@c FIXME-implementors!! It would be more helpful if the [New...] message -@c included GDB's numeric thread handle, so you could just go to that -@c thread without first checking `info threads'. -Whenever @value{GDBN} detects a new thread in your program, it displays -the target system's identification for the thread with a message in the -form @samp{[New @var{systag}]}. @var{systag} is a thread identifier -whose form varies depending on the particular system. For example, on -LynxOS, you might see - -@example -[New process 35 thread 27] -@end example - -@noindent -when @value{GDBN} notices a new thread. In contrast, on an SGI system, -the @var{systag} is simply something like @samp{process 368}, with no -further qualifier. - -@c FIXME!! (1) Does the [New...] message appear even for the very first -@c thread of a program, or does it only appear for the -@c second---i.e., when it becomes obvious we have a multithread -@c program? -@c (2) *Is* there necessarily a first thread always? Or do some -@c multithread systems permit starting a program with multiple -@c threads ab initio? - -@cindex thread number -@cindex thread identifier (GDB) -For debugging purposes, @value{GDBN} associates its own thread -number---always a single integer---with each thread in your program. - -@table @code -@item info threads -@kindex info threads -Display a summary of all threads currently in your -program. @value{GDBN} displays for each thread (in this order): - -@enumerate -@item the thread number assigned by @value{GDBN} - -@item the target system's thread identifier (@var{systag}) - -@item the current stack frame summary for that thread -@end enumerate - -@noindent -An asterisk @samp{*} to the left of the @value{GDBN} thread number -indicates the current thread. - -For example, -@end table -@c end table here to get a little more width for example - -@smallexample -(@value{GDBP}) info threads - 3 process 35 thread 27 0x34e5 in sigpause () - 2 process 35 thread 23 0x34e5 in sigpause () -* 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8) - at threadtest.c:68 -@end smallexample - -@table @code -@item thread @var{threadno} -@kindex thread @var{threadno} -Make thread number @var{threadno} the current thread. The command -argument @var{threadno} is the internal @value{GDBN} thread number, as -shown in the first field of the @samp{info threads} display. -@value{GDBN} responds by displaying the system identifier of the thread -you selected, and its current stack frame summary: - -@smallexample -@c FIXME!! This example made up; find a GDB w/threads and get real one -(@value{GDBP}) thread 2 -[Switching to process 35 thread 23] -0x34e5 in sigpause () -@end smallexample - -@noindent -As with the @samp{[New @dots{}]} message, the form of the text after -@samp{Switching to} depends on your system's conventions for identifying -threads. -@end table - -@cindex automatic thread selection -@cindex switching threads automatically -@cindex threads, automatic switching -Whenever @value{GDBN} stops your program, due to a breakpoint or a -signal, it automatically selects the thread where that breakpoint or -signal happened. @value{GDBN} alerts you to the context switch with a -message of the form @samp{[Switching to @var{systag}]} to identify the -thread. - -@xref{Thread Stops,,Stopping and starting multi-thread programs}, for -more information about how @value{GDBN} behaves when you stop and start -programs with multiple threads. - -@xref{Set Watchpoints,,Setting watchpoints}, for information about -watchpoints in programs with multiple threads. -@end ifclear - -@node Stopping -@chapter Stopping and Continuing - -The principal purposes of using a debugger are so that you can stop your -program before it terminates; or so that, if your program runs into -trouble, you can investigate and find out why. - -Inside @value{GDBN}, your program may stop for any of several reasons, such -as -@ifclear BARETARGET -a signal, -@end ifclear -a breakpoint, or reaching a new line after a @value{GDBN} -command such as @code{step}. You may then examine and change -variables, set new breakpoints or remove old ones, and then continue -execution. Usually, the messages shown by @value{GDBN} provide ample -explanation of the status of your program---but you can also explicitly -request this information at any time. - -@table @code -@item info program -@kindex info program -Display information about the status of your program: whether it is -running or not, -@ifclear BARETARGET -what process it is, -@end ifclear -and why it stopped. -@end table - -@menu -@ifclear CONLY -* Breakpoints:: Breakpoints, watchpoints, and exceptions -@end ifclear -@ifset CONLY -* Breakpoints:: Breakpoints and watchpoints -@end ifset -@c Remnant makeinfo bug requires blank line after *successful* end-if in menu: - -* Continuing and Stepping:: Resuming execution -@ifset POSIX -* Signals:: Signals -@end ifset -@ifclear BARETARGET -* Thread Stops:: Stopping and starting multi-thread programs -@end ifclear -@end menu - -@c makeinfo node-defaulting requires adjacency of @node and sectioning cmds -@c ...hence distribute @node Breakpoints over two possible @if expansions. -@c -@ifclear CONLY -@node Breakpoints -@section Breakpoints, watchpoints, and exceptions -@end ifclear -@ifset CONLY -@node Breakpoints -@section Breakpoints and watchpoints -@end ifset - -@cindex breakpoints -A @dfn{breakpoint} makes your program stop whenever a certain point in -the program is reached. For each breakpoint, you can add -conditions to control in finer detail whether your program stops. -You can set breakpoints with the @code{break} command and its variants -(@pxref{Set Breaks, ,Setting breakpoints}), to specify the place where -your program should stop by line number, function name or exact address -in the program. -@ifclear CONLY -In languages with exception handling (such as GNU C++), you can also set -breakpoints where an exception is raised (@pxref{Exception Handling,, -Breakpoints and exceptions}). -@end ifclear - -@cindex watchpoints -@cindex memory tracing -@cindex breakpoint on memory address -@cindex breakpoint on variable modification -A @dfn{watchpoint} is a special breakpoint that stops your program -when the value of an expression changes. You must use a different -command to set watchpoints (@pxref{Set Watchpoints, ,Setting -watchpoints}), but aside from that, you can manage a watchpoint like -any other breakpoint: you enable, disable, and delete both breakpoints -and watchpoints using the same commands. - -You can arrange to have values from your program displayed automatically -whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,, -Automatic display}. - -@cindex breakpoint numbers -@cindex numbers for breakpoints -@value{GDBN} assigns a number to each breakpoint or watchpoint when you -create it; these numbers are successive integers starting with one. In -many of the commands for controlling various features of breakpoints you -use the breakpoint number to say which breakpoint you want to change. -Each breakpoint may be @dfn{enabled} or @dfn{disabled}; if disabled, it has -no effect on your program until you enable it again. - -@menu -* Set Breaks:: Setting breakpoints -* Set Watchpoints:: Setting watchpoints -@ifclear CONLY -* Exception Handling:: Breakpoints and exceptions -@end ifclear - -* Delete Breaks:: Deleting breakpoints -* Disabling:: Disabling breakpoints -* Conditions:: Break conditions -* Break Commands:: Breakpoint command lists -@ifclear CONLY -* Breakpoint Menus:: Breakpoint menus -@end ifclear -@ifclear BARETARGET -* Error in Breakpoints:: ``Cannot insert breakpoints'' -@end ifclear -@end menu - -@node Set Breaks -@subsection Setting breakpoints - -@c FIXME LMB what does GDB do if no code on line of breakpt? -@c consider in particular declaration with/without initialization. -@c -@c FIXME 2 is there stuff on this already? break at fun start, already init? - -@kindex break -@kindex b -@kindex $bpnum -@cindex latest breakpoint -Breakpoints are set with the @code{break} command (abbreviated -@code{b}). The debugger convenience variable @samp{$bpnum} records the -number of the beakpoint you've set most recently; see @ref{Convenience -Vars,, Convenience variables}, for a discussion of what you can do with -convenience variables. - -You have several ways to say where the breakpoint should go. - -@table @code -@item break @var{function} -Set a breakpoint at entry to function @var{function}. -@ifclear CONLY -When using source languages that permit overloading of symbols, such as -C++, @var{function} may refer to more than one possible place to break. -@xref{Breakpoint Menus,,Breakpoint menus}, for a discussion of that situation. -@end ifclear - -@item break +@var{offset} -@itemx break -@var{offset} -Set a breakpoint some number of lines forward or back from the position -at which execution stopped in the currently selected frame. - -@item break @var{linenum} -Set a breakpoint at line @var{linenum} in the current source file. -That file is the last file whose source text was printed. This -breakpoint stops your program just before it executes any of the -code on that line. - -@item break @var{filename}:@var{linenum} -Set a breakpoint at line @var{linenum} in source file @var{filename}. - -@item break @var{filename}:@var{function} -Set a breakpoint at entry to function @var{function} found in file -@var{filename}. Specifying a file name as well as a function name is -superfluous except when multiple files contain similarly named -functions. - -@item break *@var{address} -Set a breakpoint at address @var{address}. You can use this to set -breakpoints in parts of your program which do not have debugging -information or source files. - -@item break -When called without any arguments, @code{break} sets a breakpoint at -the next instruction to be executed in the selected stack frame -(@pxref{Stack, ,Examining the Stack}). In any selected frame but the -innermost, this makes your program stop as soon as control -returns to that frame. This is similar to the effect of a -@code{finish} command in the frame inside the selected frame---except -that @code{finish} does not leave an active breakpoint. If you use -@code{break} without an argument in the innermost frame, @value{GDBN} stops -the next time it reaches the current location; this may be useful -inside loops. - -@value{GDBN} normally ignores breakpoints when it resumes execution, until at -least one instruction has been executed. If it did not do this, you -would be unable to proceed past a breakpoint without first disabling the -breakpoint. This rule applies whether or not the breakpoint already -existed when your program stopped. - -@item break @dots{} if @var{cond} -Set a breakpoint with condition @var{cond}; evaluate the expression -@var{cond} each time the breakpoint is reached, and stop only if the -value is nonzero---that is, if @var{cond} evaluates as true. -@samp{@dots{}} stands for one of the possible arguments described -above (or no argument) specifying where to break. @xref{Conditions, -,Break conditions}, for more information on breakpoint conditions. - -@item tbreak @var{args} -@kindex tbreak -Set a breakpoint enabled only for one stop. @var{args} are the -same as for the @code{break} command, and the breakpoint is set in the same -way, but the breakpoint is automatically deleted after the first time your -program stops there. @xref{Disabling, ,Disabling breakpoints}. - -@item rbreak @var{regex} -@kindex rbreak -@cindex regular expression -@c FIXME what kind of regexp? -Set breakpoints on all functions matching the regular expression -@var{regex}. This command -sets an unconditional breakpoint on all matches, printing a list of all -breakpoints it set. Once these breakpoints are set, they are treated -just like the breakpoints set with the @code{break} command. You can -delete them, disable them, or make them conditional the same way as any -other breakpoint. - -@ifclear CONLY -When debugging C++ programs, @code{rbreak} is useful for setting -breakpoints on overloaded functions that are not members of any special -classes. -@end ifclear - -@kindex info breakpoints -@cindex @code{$_} and @code{info breakpoints} -@item info breakpoints @r{[}@var{n}@r{]} -@itemx info break @r{[}@var{n}@r{]} -@itemx info watchpoints @r{[}@var{n}@r{]} -Print a table of all breakpoints and watchpoints set and not -deleted, with the following columns for each breakpoint: - -@table @emph -@item Breakpoint Numbers -@item Type -Breakpoint or watchpoint. -@item Disposition -Whether the breakpoint is marked to be disabled or deleted when hit. -@item Enabled or Disabled -Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints -that are not enabled. -@item Address -Where the breakpoint is in your program, as a memory address -@item What -Where the breakpoint is in the source for your program, as a file and -line number. -@end table - -@noindent -If a breakpoint is conditional, @code{info break} shows the condition on -the line following the affected breakpoint; breakpoint commands, if any, -are listed after that. - -@noindent -@code{info break} with a breakpoint -number @var{n} as argument lists only that breakpoint. The -convenience variable @code{$_} and the default examining-address for -the @code{x} command are set to the address of the last breakpoint -listed (@pxref{Memory, ,Examining memory}). -@end table - -@value{GDBN} allows you to set any number of breakpoints at the same place in -your program. There is nothing silly or meaningless about this. When -the breakpoints are conditional, this is even useful -(@pxref{Conditions, ,Break conditions}). - -@cindex negative breakpoint numbers -@cindex internal @value{GDBN} breakpoints -@value{GDBN} itself sometimes sets breakpoints in your program for special -purposes, such as proper handling of @code{longjmp} (in C programs). -These internal breakpoints are assigned negative numbers, starting with -@code{-1}; @samp{info breakpoints} does not display them. - -You can see these breakpoints with the @value{GDBN} maintenance command -@samp{maint info breakpoints}. - -@table @code -@kindex maint info breakpoints -@item maint info breakpoints -Using the same format as @samp{info breakpoints}, display both the -breakpoints you've set explicitly, and those @value{GDBN} is using for -internal purposes. Internal breakpoints are shown with negative -breakpoint numbers. The type column identifies what kind of breakpoint -is shown: - -@table @code -@item breakpoint -Normal, explicitly set breakpoint. - -@item watchpoint -Normal, explicitly set watchpoint. - -@item longjmp -Internal breakpoint, used to handle correctly stepping through -@code{longjmp} calls. - -@item longjmp resume -Internal breakpoint at the target of a @code{longjmp}. - -@item until -Temporary internal breakpoint used by the @value{GDBN} @code{until} command. - -@item finish -Temporary internal breakpoint used by the @value{GDBN} @code{finish} command. -@end table - -@end table - - -@node Set Watchpoints -@subsection Setting watchpoints -@cindex setting watchpoints - -You can use a watchpoint to stop execution whenever the value of an -expression changes, without having to predict a particular place -where this may happen. - -Watchpoints currently execute two orders of magnitude more slowly than -other breakpoints, but this can be well worth it to catch errors where -you have no clue what part of your program is the culprit. - -@ignore -@c this "future releases" promise has been in too long, is getting -@c embarrassing. But... -@c FIXME: in future updates, check whether hardware watchpoints in on any -@c platforms yet. As of 26jan94, they're very close on HPPA running -@c Berkeley and on Irix 4. -Some processors provide special hardware to support watchpoint -evaluation; future releases of @value{GDBN} will use such hardware if it -is available. -@end ignore - -@table @code -@kindex watch -@item watch @var{expr} -Set a watchpoint for an expression. - -@kindex info watchpoints -@item info watchpoints -This command prints a list of watchpoints and breakpoints; it is the -same as @code{info break}. -@end table - -@ifclear BARETARGET -@quotation -@cindex watchpoints and threads -@cindex threads and watchpoints -@emph{Warning:} in multi-thread programs, watchpoints have only limited -usefulness. With the current watchpoint implementation, @value{GDBN} -can only watch the value of an expression @emph{in a single thread}. If -you are confident that the expression can only change due to the current -thread's activity (and if you are also confident that no other thread -can become current), then you can use watchpoints as usual. However, -@value{GDBN} may not notice when a non-current thread's activity changes -the expression. -@end quotation -@end ifclear - -@ifclear CONLY -@node Exception Handling -@subsection Breakpoints and exceptions -@cindex exception handlers - -Some languages, such as GNU C++, implement exception handling. You can -use @value{GDBN} to examine what caused your program to raise an exception, -and to list the exceptions your program is prepared to handle at a -given point in time. - -@table @code -@item catch @var{exceptions} -@kindex catch -You can set breakpoints at active exception handlers by using the -@code{catch} command. @var{exceptions} is a list of names of exceptions -to catch. -@end table - -You can use @code{info catch} to list active exception handlers. -@xref{Frame Info, ,Information about a frame}. - -There are currently some limitations to exception handling in @value{GDBN}: - -@itemize @bullet -@item -If you call a function interactively, @value{GDBN} normally returns -control to you when the function has finished executing. If the call -raises an exception, however, the call may bypass the mechanism that -returns control to you and cause your program to simply continue -running until it hits a breakpoint, catches a signal that @value{GDBN} is -listening for, or exits. - -@item -You cannot raise an exception interactively. - -@item -You cannot install an exception handler interactively. -@end itemize - -@cindex raise exceptions -Sometimes @code{catch} is not the best way to debug exception handling: -if you need to know exactly where an exception is raised, it is better to -stop @emph{before} the exception handler is called, since that way you -can see the stack before any unwinding takes place. If you set a -breakpoint in an exception handler instead, it may not be easy to find -out where the exception was raised. - -To stop just before an exception handler is called, you need some -knowledge of the implementation. In the case of GNU C++, exceptions are -raised by calling a library function named @code{__raise_exception} -which has the following ANSI C interface: - -@example - /* @var{addr} is where the exception identifier is stored. - ID is the exception identifier. */ - void __raise_exception (void **@var{addr}, void *@var{id}); -@end example - -@noindent -To make the debugger catch all exceptions before any stack -unwinding takes place, set a breakpoint on @code{__raise_exception} -(@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}). - -With a conditional breakpoint (@pxref{Conditions, ,Break conditions}) -that depends on the value of @var{id}, you can stop your program when -a specific exception is raised. You can use multiple conditional -breakpoints to stop your program when any of a number of exceptions are -raised. -@end ifclear - -@node Delete Breaks -@subsection Deleting breakpoints - -@cindex clearing breakpoints, watchpoints -@cindex deleting breakpoints, watchpoints -It is often necessary to eliminate a breakpoint or watchpoint once it -has done its job and you no longer want your program to stop there. This -is called @dfn{deleting} the breakpoint. A breakpoint that has been -deleted no longer exists; it is forgotten. - -With the @code{clear} command you can delete breakpoints according to -where they are in your program. With the @code{delete} command you can -delete individual breakpoints or watchpoints by specifying their -breakpoint numbers. - -It is not necessary to delete a breakpoint to proceed past it. @value{GDBN} -automatically ignores breakpoints on the first instruction to be executed -when you continue execution without changing the execution address. - -@table @code -@item clear -@kindex clear -Delete any breakpoints at the next instruction to be executed in the -selected stack frame (@pxref{Selection, ,Selecting a frame}). When -the innermost frame is selected, this is a good way to delete a -breakpoint where your program just stopped. - -@item clear @var{function} -@itemx clear @var{filename}:@var{function} -Delete any breakpoints set at entry to the function @var{function}. - -@item clear @var{linenum} -@itemx clear @var{filename}:@var{linenum} -Delete any breakpoints set at or within the code of the specified line. - -@item delete @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]} -@cindex delete breakpoints -@kindex delete -@kindex d -Delete the breakpoints or watchpoints of the numbers specified as -arguments. If no argument is specified, delete all breakpoints (@value{GDBN} -asks confirmation, unless you have @code{set confirm off}). You -can abbreviate this command as @code{d}. -@end table - -@node Disabling -@subsection Disabling breakpoints - -@cindex disabled breakpoints -@cindex enabled breakpoints -Rather than deleting a breakpoint or watchpoint, you might prefer to -@dfn{disable} it. This makes the breakpoint inoperative as if it had -been deleted, but remembers the information on the breakpoint so that -you can @dfn{enable} it again later. - -You disable and enable breakpoints and watchpoints with the -@code{enable} and @code{disable} commands, optionally specifying one or -more breakpoint numbers as arguments. Use @code{info break} or -@code{info watch} to print a list of breakpoints or watchpoints if you -do not know which numbers to use. - -A breakpoint or watchpoint can have any of four different states of -enablement: - -@itemize @bullet -@item -Enabled. The breakpoint stops your program. A breakpoint set -with the @code{break} command starts out in this state. -@item -Disabled. The breakpoint has no effect on your program. -@item -Enabled once. The breakpoint stops your program, but then becomes -disabled. A breakpoint set with the @code{tbreak} command starts out in -this state. -@item -Enabled for deletion. The breakpoint stops your program, but -immediately after it does so it is deleted permanently. -@end itemize - -You can use the following commands to enable or disable breakpoints and -watchpoints: - -@table @code -@item disable @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]} -@kindex disable breakpoints -@kindex disable -@kindex dis -Disable the specified breakpoints---or all breakpoints, if none are -listed. A disabled breakpoint has no effect but is not forgotten. All -options such as ignore-counts, conditions and commands are remembered in -case the breakpoint is enabled again later. You may abbreviate -@code{disable} as @code{dis}. - -@item enable @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]} -@kindex enable breakpoints -@kindex enable -Enable the specified breakpoints (or all defined breakpoints). They -become effective once again in stopping your program. - -@item enable @r{[}breakpoints@r{]} once @var{bnums}@dots{} -Enable the specified breakpoints temporarily. @value{GDBN} disables any -of these breakpoints immediately after stopping your program. - -@item enable @r{[}breakpoints@r{]} delete @var{bnums}@dots{} -Enable the specified breakpoints to work once, then die. @value{GDBN} -deletes any of these breakpoints as soon as your program stops there. -@end table - -Save for a breakpoint set with @code{tbreak} (@pxref{Set Breaks, -,Setting breakpoints}), breakpoints that you set are initially enabled; -subsequently, they become disabled or enabled only when you use one of -the commands above. (The command @code{until} can set and delete a -breakpoint of its own, but it does not change the state of your other -breakpoints; see @ref{Continuing and Stepping, ,Continuing and -stepping}.) - -@node Conditions -@subsection Break conditions -@cindex conditional breakpoints -@cindex breakpoint conditions - -@c FIXME what is scope of break condition expr? Context where wanted? -@c in particular for a watchpoint? -The simplest sort of breakpoint breaks every time your program reaches a -specified place. You can also specify a @dfn{condition} for a -breakpoint. A condition is just a Boolean expression in your -programming language (@pxref{Expressions, ,Expressions}). A breakpoint with -a condition evaluates the expression each time your program reaches it, -and your program stops only if the condition is @emph{true}. - -This is the converse of using assertions for program validation; in that -situation, you want to stop when the assertion is violated---that is, -when the condition is false. In C, if you want to test an assertion expressed -by the condition @var{assert}, you should set the condition -@samp{! @var{assert}} on the appropriate breakpoint. - -Conditions are also accepted for watchpoints; you may not need them, -since a watchpoint is inspecting the value of an expression anyhow---but -it might be simpler, say, to just set a watchpoint on a variable name, -and specify a condition that tests whether the new value is an interesting -one. - -Break conditions can have side effects, and may even call functions in -your program. This can be useful, for example, to activate functions -that log program progress, or to use your own print functions to -format special data structures. The effects are completely predictable -unless there is another enabled breakpoint at the same address. (In -that case, @value{GDBN} might see the other breakpoint first and stop your -program without checking the condition of this one.) Note that -breakpoint commands are usually more convenient and flexible for the -purpose of performing side effects when a breakpoint is reached -(@pxref{Break Commands, ,Breakpoint command lists}). - -Break conditions can be specified when a breakpoint is set, by using -@samp{if} in the arguments to the @code{break} command. @xref{Set -Breaks, ,Setting breakpoints}. They can also be changed at any time -with the @code{condition} command. The @code{watch} command does not -recognize the @code{if} keyword; @code{condition} is the only way to -impose a further condition on a watchpoint. - -@table @code -@item condition @var{bnum} @var{expression} -@kindex condition -Specify @var{expression} as the break condition for breakpoint or -watchpoint number @var{bnum}. After you set a condition, breakpoint -@var{bnum} stops your program only if the value of @var{expression} is -true (nonzero, in C). When you use @code{condition}, @value{GDBN} -checks @var{expression} immediately for syntactic correctness, and to -determine whether symbols in it have referents in the context of your -breakpoint. -@c FIXME so what does GDB do if there is no referent? Moreover, what -@c about watchpoints? -@value{GDBN} does -not actually evaluate @var{expression} at the time the @code{condition} -command is given, however. @xref{Expressions, ,Expressions}. - -@item condition @var{bnum} -Remove the condition from breakpoint number @var{bnum}. It becomes -an ordinary unconditional breakpoint. -@end table - -@cindex ignore count (of breakpoint) -A special case of a breakpoint condition is to stop only when the -breakpoint has been reached a certain number of times. This is so -useful that there is a special way to do it, using the @dfn{ignore -count} of the breakpoint. Every breakpoint has an ignore count, which -is an integer. Most of the time, the ignore count is zero, and -therefore has no effect. But if your program reaches a breakpoint whose -ignore count is positive, then instead of stopping, it just decrements -the ignore count by one and continues. As a result, if the ignore count -value is @var{n}, the breakpoint does not stop the next @var{n} times -your program reaches it. - -@table @code -@item ignore @var{bnum} @var{count} -@kindex ignore -Set the ignore count of breakpoint number @var{bnum} to @var{count}. -The next @var{count} times the breakpoint is reached, your program's -execution does not stop; other than to decrement the ignore count, @value{GDBN} -takes no action. - -To make the breakpoint stop the next time it is reached, specify -a count of zero. - -When you use @code{continue} to resume execution of your program from a -breakpoint, you can specify an ignore count directly as an argument to -@code{continue}, rather than using @code{ignore}. @xref{Continuing and -Stepping,,Continuing and stepping}. - -If a breakpoint has a positive ignore count and a condition, the -condition is not checked. Once the ignore count reaches zero, -@value{GDBN} resumes checking the condition. - -You could achieve the effect of the ignore count with a condition such -as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that -is decremented each time. @xref{Convenience Vars, ,Convenience -variables}. -@end table - -@node Break Commands -@subsection Breakpoint command lists - -@cindex breakpoint commands -You can give any breakpoint (or watchpoint) a series of commands to -execute when your program stops due to that breakpoint. For example, you -might want to print the values of certain expressions, or enable other -breakpoints. - -@table @code -@item commands @r{[}@var{bnum}@r{]} -@itemx @dots{} @var{command-list} @dots{} -@itemx end -@kindex commands -@kindex end -Specify a list of commands for breakpoint number @var{bnum}. The commands -themselves appear on the following lines. Type a line containing just -@code{end} to terminate the commands. - -To remove all commands from a breakpoint, type @code{commands} and -follow it immediately with @code{end}; that is, give no commands. - -With no @var{bnum} argument, @code{commands} refers to the last -breakpoint or watchpoint set (not to the breakpoint most recently -encountered). -@end table - -Pressing @key{RET} as a means of repeating the last @value{GDBN} command is -disabled within a @var{command-list}. - -You can use breakpoint commands to start your program up again. Simply -use the @code{continue} command, or @code{step}, or any other command -that resumes execution. - -Any other commands in the command list, after a command that resumes -execution, are ignored. This is because any time you resume execution -(even with a simple @code{next} or @code{step}), you may encounter -another breakpoint---which could have its own command list, leading to -ambiguities about which list to execute. - -@kindex silent -If the first command you specify in a command list is @code{silent}, the -usual message about stopping at a breakpoint is not printed. This may -be desirable for breakpoints that are to print a specific message and -then continue. If none of the remaining commands print anything, you -see no sign that the breakpoint was reached. @code{silent} is -meaningful only at the beginning of a breakpoint command list. - -The commands @code{echo}, @code{output}, and @code{printf} allow you to -print precisely controlled output, and are often useful in silent -breakpoints. @xref{Output, ,Commands for controlled output}. - -For example, here is how you could use breakpoint commands to print the -value of @code{x} at entry to @code{foo} whenever @code{x} is positive. - -@example -break foo if x>0 -commands -silent -printf "x is %d\n",x -cont -end -@end example - -One application for breakpoint commands is to compensate for one bug so -you can test for another. Put a breakpoint just after the erroneous line -of code, give it a condition to detect the case in which something -erroneous has been done, and give it commands to assign correct values -to any variables that need them. End with the @code{continue} command -so that your program does not stop, and start with the @code{silent} -command so that no output is produced. Here is an example: - -@example -break 403 -commands -silent -set x = y + 4 -cont -end -@end example - -@ifclear CONLY -@node Breakpoint Menus -@subsection Breakpoint menus -@cindex overloading -@cindex symbol overloading - -Some programming languages (notably C++) permit a single function name -to be defined several times, for application in different contexts. -This is called @dfn{overloading}. When a function name is overloaded, -@samp{break @var{function}} is not enough to tell @value{GDBN} where you want -a breakpoint. If you realize this is a problem, you can use -something like @samp{break @var{function}(@var{types})} to specify which -particular version of the function you want. Otherwise, @value{GDBN} offers -you a menu of numbered choices for different possible breakpoints, and -waits for your selection with the prompt @samp{>}. The first two -options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1} -sets a breakpoint at each definition of @var{function}, and typing -@kbd{0} aborts the @code{break} command without setting any new -breakpoints. - -For example, the following session excerpt shows an attempt to set a -breakpoint at the overloaded symbol @code{String::after}. -We choose three particular definitions of that function name: - -@c FIXME! This is likely to change to show arg type lists, at least -@smallexample -(@value{GDBP}) b String::after -[0] cancel -[1] all -[2] file:String.cc; line number:867 -[3] file:String.cc; line number:860 -[4] file:String.cc; line number:875 -[5] file:String.cc; line number:853 -[6] file:String.cc; line number:846 -[7] file:String.cc; line number:735 -> 2 4 6 -Breakpoint 1 at 0xb26c: file String.cc, line 867. -Breakpoint 2 at 0xb344: file String.cc, line 875. -Breakpoint 3 at 0xafcc: file String.cc, line 846. -Multiple breakpoints were set. -Use the "delete" command to delete unwanted - breakpoints. -(@value{GDBP}) -@end smallexample -@end ifclear - -@ifclear BARETARGET -@node Error in Breakpoints -@subsection ``Cannot insert breakpoints'' - -@c FIXME: "cannot insert breakpoints" error, v unclear. -@c Q in pending mail to Gilmore. ---pesch@cygnus.com, 26mar91 -@c some light may be shed by looking at instances of -@c ONE_PROCESS_WRITETEXT. But error message seems possible otherwise -@c too. pesch, 20sep91 -Under some operating systems, breakpoints cannot be used in a program if -any other process is running that program. In this situation, -attempting to run or continue a program with a breakpoint causes @value{GDBN} -to stop the other process. - -When this happens, you have three ways to proceed: - -@enumerate -@item -Remove or disable the breakpoints, then continue. - -@item -Suspend @value{GDBN}, and copy the file containing your program to a new name. -Resume @value{GDBN} and use the @code{exec-file} command to specify that @value{GDBN} -should run your program under that name. Then start your program again. - -@c FIXME: RMS commented here "Show example". Maybe when someone -@c explains the first FIXME: in this section... - -@item -Relink your program so that the text segment is nonsharable, using the -linker option @samp{-N}. The operating system limitation may not apply -to nonsharable executables. -@end enumerate -@end ifclear - -@node Continuing and Stepping -@section Continuing and stepping - -@cindex stepping -@cindex continuing -@cindex resuming execution -@dfn{Continuing} means resuming program execution until your program -completes normally. In contrast, @dfn{stepping} means executing just -one more ``step'' of your program, where ``step'' may mean either one -line of source code, or one machine instruction (depending on what -particular command you use). Either when continuing -or when stepping, your program may stop even sooner, due to -@ifset BARETARGET -a breakpoint. -@end ifset -@ifclear BARETARGET -a breakpoint or a signal. (If due to a signal, you may want to use -@code{handle}, or use @samp{signal 0} to resume execution. -@xref{Signals, ,Signals}.) -@end ifclear - -@table @code -@item continue @r{[}@var{ignore-count}@r{]} -@itemx c @r{[}@var{ignore-count}@r{]} -@itemx fg @r{[}@var{ignore-count}@r{]} -@kindex continue -@kindex c -@kindex fg -Resume program execution, at the address where your program last stopped; -any breakpoints set at that address are bypassed. The optional argument -@var{ignore-count} allows you to specify a further number of times to -ignore a breakpoint at this location; its effect is like that of -@code{ignore} (@pxref{Conditions, ,Break conditions}). - -The argument @var{ignore-count} is meaningful only when your program -stopped due to a breakpoint. At other times, the argument to -@code{continue} is ignored. - -The synonyms @code{c} and @code{fg} are provided purely for convenience, -and have exactly the same behavior as @code{continue}. -@end table - -To resume execution at a different place, you can use @code{return} -(@pxref{Returning, ,Returning from a function}) to go back to the -calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a -different address}) to go to an arbitrary location in your program. - -A typical technique for using stepping is to set a breakpoint -@ifclear CONLY -(@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}) -@end ifclear -@ifset CONLY -(@pxref{Breakpoints, ,Breakpoints and watchpoints}) -@end ifset -at the -beginning of the function or the section of your program where a -problem is believed to lie, run your program until it stops at that -breakpoint, and then step through the suspect area, examining the -variables that are interesting, until you see the problem happen. - -@table @code -@item step -@kindex step -@kindex s -Continue running your program until control reaches a different source -line, then stop it and return control to @value{GDBN}. This command is -abbreviated @code{s}. - -@quotation -@c "without debugging information" is imprecise; actually "without line -@c numbers in the debugging information". (gcc -g1 has debugging info but -@c not line numbers). But it seems complex to try to make that -@c distinction here. -@emph{Warning:} If you use the @code{step} command while control is -within a function that was compiled without debugging information, -execution proceeds until control reaches a function that does have -debugging information. Likewise, it will not step into a function which -is compiled without debugging information. To step through functions -without debugging information, use the @code{stepi} command, described -below. -@end quotation - -@item step @var{count} -Continue running as in @code{step}, but do so @var{count} times. If a -breakpoint is reached, -@ifclear BARETARGET -or a signal not related to stepping occurs before @var{count} steps, -@end ifclear -stepping stops right away. - -@item next @r{[}@var{count}@r{]} -@kindex next -@kindex n -Continue to the next source line in the current (innermost) stack frame. -Similar to @code{step}, but any function calls appearing within the line -of code are executed without stopping. Execution stops when control -reaches a different line of code at the stack level which was executing -when the @code{next} command was given. This command is abbreviated -@code{n}. - -An argument @var{count} is a repeat count, as for @code{step}. - -@code{next} within a function that lacks debugging information acts like -@code{step}, but any function calls appearing within the code of the -function are executed without stopping. - -@item finish -@kindex finish -Continue running until just after function in the selected stack frame -returns. Print the returned value (if any). - -Contrast this with the @code{return} command (@pxref{Returning, -,Returning from a function}). - -@item until -@kindex until -@itemx u -@kindex u -Continue running until a source line past the current line, in the -current stack frame, is reached. This command is used to avoid single -stepping through a loop more than once. It is like the @code{next} -command, except that when @code{until} encounters a jump, it -automatically continues execution until the program counter is greater -than the address of the jump. - -This means that when you reach the end of a loop after single stepping -though it, @code{until} makes your program continue execution until it -exits the loop. In contrast, a @code{next} command at the end of a loop -simply steps back to the beginning of the loop, which forces you to step -through the next iteration. - -@code{until} always stops your program if it attempts to exit the current -stack frame. - -@code{until} may produce somewhat counterintuitive results if the order -of machine code does not match the order of the source lines. For -example, in the following excerpt from a debugging session, the @code{f} -(@code{frame}) command shows that execution is stopped at line -@code{206}; yet when we use @code{until}, we get to line @code{195}: - -@example -(@value{GDBP}) f -#0 main (argc=4, argv=0xf7fffae8) at m4.c:206 -206 expand_input(); -(@value{GDBP}) until -195 for ( ; argc > 0; NEXTARG) @{ -@end example - -This happened because, for execution efficiency, the compiler had -generated code for the loop closure test at the end, rather than the -start, of the loop---even though the test in a C @code{for}-loop is -written before the body of the loop. The @code{until} command appeared -to step back to the beginning of the loop when it advanced to this -expression; however, it has not really gone to an earlier -statement---not in terms of the actual machine code. - -@code{until} with no argument works by means of single -instruction stepping, and hence is slower than @code{until} with an -argument. - -@item until @var{location} -@itemx u @var{location} -Continue running your program until either the specified location is -reached, or the current stack frame returns. @var{location} is any of -the forms of argument acceptable to @code{break} (@pxref{Set Breaks, -,Setting breakpoints}). This form of the command uses breakpoints, -and hence is quicker than @code{until} without an argument. - -@item stepi -@itemx si -@kindex stepi -@kindex si -Execute one machine instruction, then stop and return to the debugger. - -It is often useful to do @samp{display/i $pc} when stepping by machine -instructions. This makes @value{GDBN} automatically display the next -instruction to be executed, each time your program stops. @xref{Auto -Display,, Automatic display}. - -An argument is a repeat count, as in @code{step}. - -@need 750 -@item nexti -@itemx ni -@kindex nexti -@kindex ni -Execute one machine instruction, but if it is a function call, -proceed until the function returns. - -An argument is a repeat count, as in @code{next}. -@end table - -@ifset POSIX -@node Signals -@section Signals -@cindex signals - -A signal is an asynchronous event that can happen in a program. The -operating system defines the possible kinds of signals, and gives each -kind a name and a number. For example, in Unix @code{SIGINT} is the -signal a program gets when you type an interrupt (often @kbd{C-c}); -@code{SIGSEGV} is the signal a program gets from referencing a place in -memory far away from all the areas in use; @code{SIGALRM} occurs when -the alarm clock timer goes off (which happens only if your program has -requested an alarm). - -@cindex fatal signals -Some signals, including @code{SIGALRM}, are a normal part of the -functioning of your program. Others, such as @code{SIGSEGV}, indicate -errors; these signals are @dfn{fatal} (kill your program immediately) if the -program has not specified in advance some other way to handle the signal. -@code{SIGINT} does not indicate an error in your program, but it is normally -fatal so it can carry out the purpose of the interrupt: to kill the program. - -@value{GDBN} has the ability to detect any occurrence of a signal in your -program. You can tell @value{GDBN} in advance what to do for each kind of -signal. - -@cindex handling signals -Normally, @value{GDBN} is set up to ignore non-erroneous signals like @code{SIGALRM} -(so as not to interfere with their role in the functioning of your program) -but to stop your program immediately whenever an error signal happens. -You can change these settings with the @code{handle} command. - -@table @code -@item info signals -@kindex info signals -Print a table of all the kinds of signals and how @value{GDBN} has been told to -handle each one. You can use this to see the signal numbers of all -the defined types of signals. - -@item handle @var{signal} @var{keywords}@dots{} -@kindex handle -Change the way @value{GDBN} handles signal @var{signal}. @var{signal} can be the -number of a signal or its name (with or without the @samp{SIG} at the -beginning). The @var{keywords} say what change to make. -@end table - -@c @group -The keywords allowed by the @code{handle} command can be abbreviated. -Their full names are: - -@table @code -@item nostop -@value{GDBN} should not stop your program when this signal happens. It may -still print a message telling you that the signal has come in. - -@item stop -@value{GDBN} should stop your program when this signal happens. This implies -the @code{print} keyword as well. - -@item print -@value{GDBN} should print a message when this signal happens. - -@item noprint -@value{GDBN} should not mention the occurrence of the signal at all. This -implies the @code{nostop} keyword as well. - -@item pass -@value{GDBN} should allow your program to see this signal; your program -can handle the signal, or else it may terminate if the signal is fatal -and not handled. - -@item nopass -@value{GDBN} should not allow your program to see this signal. -@end table -@c @end group - -When a signal stops your program, the signal is not visible until you -continue. Your program sees the signal then, if @code{pass} is in -effect for the signal in question @emph{at that time}. In other words, -after @value{GDBN} reports a signal, you can use the @code{handle} -command with @code{pass} or @code{nopass} to control whether your -program sees that signal when you continue. - -You can also use the @code{signal} command to prevent your program from -seeing a signal, or cause it to see a signal it normally would not see, -or to give it any signal at any time. For example, if your program stopped -due to some sort of memory reference error, you might store correct -values into the erroneous variables and continue, hoping to see more -execution; but your program would probably terminate immediately as -a result of the fatal signal once it saw the signal. To prevent this, -you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your -program a signal}. -@end ifset - -@ifclear BARETARGET -@node Thread Stops -@section Stopping and starting multi-thread programs - -When your program has multiple threads (@pxref{Threads,, Debugging -programs with multiple threads}), you can choose whether to set -breakpoints on all threads, or on a particular thread. - -@table @code -@cindex breakpoints and threads -@cindex thread breakpoints -@kindex break @dots{} thread @var{threadno} -@item break @var{linespec} thread @var{threadno} -@itemx break @var{linespec} thread @var{threadno} if @dots{} -Use the qualifier @samp{thread @var{threadno}} with a breakpoint command -to specify that you only want @value{GDBN} to stop the program when a -particular thread reaches this breakpoint. @var{threadno} is one of the -numeric thread identifiers assigned by @value{GDBN}, shown in the first -column of the @samp{info threads} display. - -If you do not specify @samp{thread @var{threadno}} when you set a -breakpoint, the breakpoint applies to @emph{all} threads of your -program. - -You can use the @code{thread} qualifier on conditional breakpoints as -well; in this case, place @samp{thread @var{threadno}} before the -breakpoint condition, like this: - -@smallexample -(gdb) break frik.c:13 thread 28 if bartab > lim -@end smallexample -@end table - -@cindex stopped threads -@cindex threads, stopped -Whenever your program stops under @value{GDBN} for any reason, -@emph{all} threads of execution stop, not just the current thread. This -allows you to examine the overall state of the program, including -switching between threads, without worrying that things may change -underfoot. - -@cindex continuing threads -@cindex threads, continuing -Conversely, whenever you restart the program, @emph{all} threads start -executing. @emph{This is true even when single-stepping} with commands -like @code{step} or @code{next}. - -In particular, @value{GDBN} cannot single-step all threads in lockstep. -Since thread scheduling is up to your debugging target's operating -system (not controlled by @value{GDBN}), other threads may -execute more than one statement while the current thread completes a -single step. Moreover, in general other threads stop in the middle of a -statement, rather than at a clean statement boundary, when the program -stops. - -You might even find your program stopped in another thread after -continuing or even single-stepping. This happens whenever some other -thread runs into a breakpoint, a signal, or an exception before the -first thread completes whatever you requested. -@end ifclear - -@node Stack -@chapter Examining the Stack - -When your program has stopped, the first thing you need to know is where it -stopped and how it got there. - -@cindex call stack -Each time your program performs a function call, the information about -where in your program the call was made from is saved in a block of data -called a @dfn{stack frame}. The frame also contains the arguments of the -call and the local variables of the function that was called. All the -stack frames are allocated in a region of memory called the @dfn{call -stack}. - -When your program stops, the @value{GDBN} commands for examining the -stack allow you to see all of this information. - -@cindex selected frame -One of the stack frames is @dfn{selected} by @value{GDBN} and many -@value{GDBN} commands refer implicitly to the selected frame. In -particular, whenever you ask @value{GDBN} for the value of a variable in -your program, the value is found in the selected frame. There are -special @value{GDBN} commands to select whichever frame you are -interested in. - -When your program stops, @value{GDBN} automatically selects the -currently executing frame and describes it briefly as the @code{frame} -command does (@pxref{Frame Info, ,Information about a frame}). - -@menu -* Frames:: Stack frames -* Backtrace:: Backtraces -* Selection:: Selecting a frame -* Frame Info:: Information on a frame -@ifset MIPS -* MIPS Stack:: MIPS machines and the function stack -@end ifset -@end menu - -@node Frames -@section Stack frames - -@cindex frame -@cindex stack frame -The call stack is divided up into contiguous pieces called @dfn{stack -frames}, or @dfn{frames} for short; each frame is the data associated -with one call to one function. The frame contains the arguments given -to the function, the function's local variables, and the address at -which the function is executing. - -@cindex initial frame -@cindex outermost frame -@cindex innermost frame -When your program is started, the stack has only one frame, that of the -function @code{main}. This is called the @dfn{initial} frame or the -@dfn{outermost} frame. Each time a function is called, a new frame is -made. Each time a function returns, the frame for that function invocation -is eliminated. If a function is recursive, there can be many frames for -the same function. The frame for the function in which execution is -actually occurring is called the @dfn{innermost} frame. This is the most -recently created of all the stack frames that still exist. - -@cindex frame pointer -Inside your program, stack frames are identified by their addresses. A -stack frame consists of many bytes, each of which has its own address; each -kind of computer has a convention for choosing one of those bytes whose -address serves as the address of the frame. Usually this address is kept -in a register called the @dfn{frame pointer register} while execution is -going on in that frame. - -@cindex frame number -@value{GDBN} assigns numbers to all existing stack frames, starting with -zero for the innermost frame, one for the frame that called it, -and so on upward. These numbers do not really exist in your program; -they are assigned by @value{GDBN} to give you a way of designating stack -frames in @value{GDBN} commands. - -@c below produces an acceptable overful hbox. --mew 13aug1993 -@cindex frameless execution -Some compilers provide a way to compile functions so that they operate -without stack frames. (For example, the @code{@value{GCC}} option -@samp{-fomit-frame-pointer} generates functions without a frame.) -This is occasionally done with heavily used library functions to save -the frame setup time. @value{GDBN} has limited facilities for dealing -with these function invocations. If the innermost function invocation -has no stack frame, @value{GDBN} nevertheless regards it as though -it had a separate frame, which is numbered zero as usual, allowing -correct tracing of the function call chain. However, @value{GDBN} has -no provision for frameless functions elsewhere in the stack. - -@node Backtrace -@section Backtraces - -A backtrace is a summary of how your program got where it is. It shows one -line per frame, for many frames, starting with the currently executing -frame (frame zero), followed by its caller (frame one), and on up the -stack. - -@table @code -@item backtrace -@itemx bt -@kindex backtrace -@kindex bt -Print a backtrace of the entire stack: one line per frame for all -frames in the stack. - -You can stop the backtrace at any time by typing the system interrupt -character, normally @kbd{C-c}. - -@item backtrace @var{n} -@itemx bt @var{n} -Similar, but print only the innermost @var{n} frames. - -@item backtrace -@var{n} -@itemx bt -@var{n} -Similar, but print only the outermost @var{n} frames. -@end table - -@kindex where -@kindex info stack -@kindex info s -The names @code{where} and @code{info stack} (abbreviated @code{info s}) -are additional aliases for @code{backtrace}. - -Each line in the backtrace shows the frame number and the function name. -The program counter value is also shown---unless you use @code{set -print address off}. The backtrace also shows the source file name and -line number, as well as the arguments to the function. The program -counter value is omitted if it is at the beginning of the code for that -line number. - -Here is an example of a backtrace. It was made with the command -@samp{bt 3}, so it shows the innermost three frames. - -@smallexample -@group -#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) - at builtin.c:993 -#1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242 -#2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08) - at macro.c:71 -(More stack frames follow...) -@end group -@end smallexample - -@noindent -The display for frame zero does not begin with a program counter -value, indicating that your program has stopped at the beginning of the -code for line @code{993} of @code{builtin.c}. - -@node Selection -@section Selecting a frame - -Most commands for examining the stack and other data in your program work on -whichever stack frame is selected at the moment. Here are the commands for -selecting a stack frame; all of them finish by printing a brief description -of the stack frame just selected. - -@table @code -@item frame @var{n} -@itemx f @var{n} -@kindex frame -@kindex f -Select frame number @var{n}. Recall that frame zero is the innermost -(currently executing) frame, frame one is the frame that called the -innermost one, and so on. The highest-numbered frame is the one for -@code{main}. - -@item frame @var{addr} -@itemx f @var{addr} -Select the frame at address @var{addr}. This is useful mainly if the -chaining of stack frames has been damaged by a bug, making it -impossible for @value{GDBN} to assign numbers properly to all frames. In -addition, this can be useful when your program has multiple stacks and -switches between them. - -@ifclear H8EXCLUSIVE -On the SPARC architecture, @code{frame} needs two addresses to -select an arbitrary frame: a frame pointer and a stack pointer. - -On the MIPS and Alpha architecture, it needs two addresses: a stack -pointer and a program counter. - -On the 29k architecture, it needs three addresses: a register stack -pointer, a program counter, and a memory stack pointer. -@c note to future updaters: this is conditioned on a flag -@c SETUP_ARBITRARY_FRAME in the tm-*.h files. The above is up to date -@c as of 27 Jan 1994. -@end ifclear - -@item up @var{n} -@kindex up -Move @var{n} frames up the stack. For positive numbers @var{n}, this -advances toward the outermost frame, to higher frame numbers, to frames -that have existed longer. @var{n} defaults to one. - -@item down @var{n} -@kindex down -@kindex do -Move @var{n} frames down the stack. For positive numbers @var{n}, this -advances toward the innermost frame, to lower frame numbers, to frames -that were created more recently. @var{n} defaults to one. You may -abbreviate @code{down} as @code{do}. -@end table - -All of these commands end by printing two lines of output describing the -frame. The first line shows the frame number, the function name, the -arguments, and the source file and line number of execution in that -frame. The second line shows the text of that source line. - -@need 1000 -For example: - -@smallexample -@group -(@value{GDBP}) up -#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) - at env.c:10 -10 read_input_file (argv[i]); -@end group -@end smallexample - -After such a printout, the @code{list} command with no arguments -prints ten lines centered on the point of execution in the frame. -@xref{List, ,Printing source lines}. - -@table @code -@item up-silently @var{n} -@itemx down-silently @var{n} -@kindex down-silently -@kindex up-silently -These two commands are variants of @code{up} and @code{down}, -respectively; they differ in that they do their work silently, without -causing display of the new frame. They are intended primarily for use -in @value{GDBN} command scripts, where the output might be unnecessary and -distracting. -@end table - -@node Frame Info -@section Information about a frame - -There are several other commands to print information about the selected -stack frame. - -@table @code -@item frame -@itemx f -When used without any argument, this command does not change which -frame is selected, but prints a brief description of the currently -selected stack frame. It can be abbreviated @code{f}. With an -argument, this command is used to select a stack frame. -@xref{Selection, ,Selecting a frame}. - -@item info frame -@itemx info f -@kindex info frame -@kindex info f -This command prints a verbose description of the selected stack frame, -including the address of the frame, the addresses of the next frame down -(called by this frame) and the next frame up (caller of this frame), the -language that the source code corresponding to this frame was written in, -the address of the frame's arguments, the program counter saved in it -(the address of execution in the caller frame), and which registers -were saved in the frame. The verbose description is useful when -something has gone wrong that has made the stack format fail to fit -the usual conventions. - -@item info frame @var{addr} -@itemx info f @var{addr} -Print a verbose description of the frame at address @var{addr}, without -selecting that frame. The selected frame remains unchanged by this -command. This requires the same kind of address (more than one for some -architectures) that you specify in the @code{frame} command. -@xref{Selection, ,Selecting a frame}. - -@item info args -@kindex info args -Print the arguments of the selected frame, each on a separate line. - -@item info locals -@kindex info locals -Print the local variables of the selected frame, each on a separate -line. These are all variables (declared either static or automatic) -accessible at the point of execution of the selected frame. - -@ifclear CONLY -@item info catch -@kindex info catch -@cindex catch exceptions -@cindex exception handlers -Print a list of all the exception handlers that are active in the -current stack frame at the current point of execution. To see other -exception handlers, visit the associated frame (using the @code{up}, -@code{down}, or @code{frame} commands); then type @code{info catch}. -@xref{Exception Handling, ,Breakpoints and exceptions}. -@end ifclear -@end table - -@ifset MIPS -@node MIPS Stack -@section MIPS machines and the function stack - -@cindex stack on MIPS -@cindex MIPS stack -MIPS based computers use an unusual stack frame, which sometimes -requires @value{GDBN} to search backward in the object code to find the -beginning of a function. - -@cindex response time, MIPS debugging -To improve response time (especially for embedded applications, where -@value{GDBN} may be restricted to a slow serial line for this search) -you may want to limit the size of this search, using one of these -commands: -@c FIXME! So what happens when GDB does *not* find the beginning of a -@c function? - -@cindex @code{heuristic-fence-post} (MIPS) -@table @code -@item set heuristic-fence-post @var{limit} -Restrict @value{GDBN} to examining at most @var{limit} bytes in its search -for the beginning of a function. A value of @code{0} (the default) -means there is no limit. - -@item show heuristic-fence-post -Display the current limit. -@end table - -@noindent -These commands are available @emph{only} when @value{GDBN} is configured -for debugging programs on MIPS processors. -@end ifset - -@node Source -@chapter Examining Source Files - -@value{GDBN} can print parts of your program's source, since the debugging -information recorded in the program tells @value{GDBN} what source files were -used to build it. When your program stops, @value{GDBN} spontaneously prints -the line where it stopped. Likewise, when you select a stack frame -(@pxref{Selection, ,Selecting a frame}), @value{GDBN} prints the line where -execution in that frame has stopped. You can print other portions of -source files by explicit command. - -@ifclear DOSHOST -If you use @value{GDBN} through its GNU Emacs interface, you may prefer to use -Emacs facilities to view source; @pxref{Emacs, ,Using @value{GDBN} under GNU -Emacs}. -@end ifclear - -@menu -* List:: Printing source lines -@ifclear DOSHOST -* Search:: Searching source files -@end ifclear - -* Source Path:: Specifying source directories -* Machine Code:: Source and machine code -@end menu - -@node List -@section Printing source lines - -@kindex list -@kindex l -To print lines from a source file, use the @code{list} command -(abbreviated @code{l}). There are several ways to specify what part -of the file you want to print. - -Here are the forms of the @code{list} command most commonly used: - -@table @code -@item list @var{linenum} -Print lines centered around line number @var{linenum} in the -current source file. - -@item list @var{function} -Print lines centered around the beginning of function -@var{function}. - -@item list -Print more lines. If the last lines printed were printed with a -@code{list} command, this prints lines following the last lines -printed; however, if the last line printed was a solitary line printed -as part of displaying a stack frame (@pxref{Stack, ,Examining the -Stack}), this prints lines centered around that line. - -@item list - -Print lines just before the lines last printed. -@end table - -By default, @value{GDBN} prints ten source lines with any of these forms of -the @code{list} command. You can change this using @code{set listsize}: - -@table @code -@item set listsize @var{count} -@kindex set listsize -Make the @code{list} command display @var{count} source lines (unless -the @code{list} argument explicitly specifies some other number). - -@item show listsize -@kindex show listsize -Display the number of lines that @code{list} prints. -@end table - -Repeating a @code{list} command with @key{RET} discards the argument, -so it is equivalent to typing just @code{list}. This is more useful -than listing the same lines again. An exception is made for an -argument of @samp{-}; that argument is preserved in repetition so that -each repetition moves up in the source file. - -@cindex linespec -In general, the @code{list} command expects you to supply zero, one or two -@dfn{linespecs}. Linespecs specify source lines; there are several ways -of writing them but the effect is always to specify some source line. -Here is a complete description of the possible arguments for @code{list}: - -@table @code -@item list @var{linespec} -Print lines centered around the line specified by @var{linespec}. - -@item list @var{first},@var{last} -Print lines from @var{first} to @var{last}. Both arguments are -linespecs. - -@item list ,@var{last} -Print lines ending with @var{last}. - -@item list @var{first}, -Print lines starting with @var{first}. - -@item list + -Print lines just after the lines last printed. - -@item list - -Print lines just before the lines last printed. - -@item list -As described in the preceding table. -@end table - -Here are the ways of specifying a single source line---all the -kinds of linespec. - -@table @code -@item @var{number} -Specifies line @var{number} of the current source file. -When a @code{list} command has two linespecs, this refers to -the same source file as the first linespec. - -@item +@var{offset} -Specifies the line @var{offset} lines after the last line printed. -When used as the second linespec in a @code{list} command that has -two, this specifies the line @var{offset} lines down from the -first linespec. - -@item -@var{offset} -Specifies the line @var{offset} lines before the last line printed. - -@item @var{filename}:@var{number} -Specifies line @var{number} in the source file @var{filename}. - -@item @var{function} -@c FIXME: "of the open-brace" is C-centric. When we add other langs... -Specifies the line of the open-brace that begins the body of the -function @var{function}. - -@item @var{filename}:@var{function} -Specifies the line of the open-brace that begins the body of the -function @var{function} in the file @var{filename}. You only need the -file name with a function name to avoid ambiguity when there are -identically named functions in different source files. - -@item *@var{address} -Specifies the line containing the program address @var{address}. -@var{address} may be any expression. -@end table - -@ifclear DOSHOST -@node Search -@section Searching source files -@cindex searching -@kindex reverse-search - -There are two commands for searching through the current source file for a -regular expression. - -@table @code -@item forward-search @var{regexp} -@itemx search @var{regexp} -@kindex search -@kindex forward-search -The command @samp{forward-search @var{regexp}} checks each line, -starting with the one following the last line listed, for a match for -@var{regexp}. It lists the line that is found. You can use -synonym @samp{search @var{regexp}} or abbreviate the command name as -@code{fo}. - -@item reverse-search @var{regexp} -The command @samp{reverse-search @var{regexp}} checks each line, starting -with the one before the last line listed and going backward, for a match -for @var{regexp}. It lists the line that is found. You can abbreviate -this command as @code{rev}. -@end table -@end ifclear - -@node Source Path -@section Specifying source directories - -@cindex source path -@cindex directories for source files -Executable programs sometimes do not record the directories of the source -files from which they were compiled, just the names. Even when they do, -the directories could be moved between the compilation and your debugging -session. @value{GDBN} has a list of directories to search for source files; -this is called the @dfn{source path}. Each time @value{GDBN} wants a source file, -it tries all the directories in the list, in the order they are present -in the list, until it finds a file with the desired name. Note that -the executable search path is @emph{not} used for this purpose. Neither is -the current working directory, unless it happens to be in the source -path. - -If @value{GDBN} cannot find a source file in the source path, and the -object program records a directory, @value{GDBN} tries that directory -too. If the source path is empty, and there is no record of the -compilation directory, @value{GDBN} looks in the current directory as a -last resort. - -Whenever you reset or rearrange the source path, @value{GDBN} clears out -any information it has cached about where source files are found and where -each line is in the file. - -@kindex directory -When you start @value{GDBN}, its source path is empty. -To add other directories, use the @code{directory} command. - -@table @code -@item directory @var{dirname} @dots{} -Add directory @var{dirname} to the front of the source path. Several -directory names may be given to this command, separated by @samp{:} or -whitespace. You may specify a directory that is already in the source -path; this moves it forward, so @value{GDBN} searches it sooner. - -@kindex cdir -@kindex cwd -@kindex $cdir -@kindex $cwd -@cindex compilation directory -@cindex current directory -@cindex working directory -@cindex directory, current -@cindex directory, compilation -You can use the string @samp{$cdir} to refer to the compilation -directory (if one is recorded), and @samp{$cwd} to refer to the current -working directory. @samp{$cwd} is not the same as @samp{.}---the former -tracks the current working directory as it changes during your @value{GDBN} -session, while the latter is immediately expanded to the current -directory at the time you add an entry to the source path. - -@item directory -Reset the source path to empty again. This requires confirmation. - -@c RET-repeat for @code{directory} is explicitly disabled, but since -@c repeating it would be a no-op we do not say that. (thanks to RMS) - -@item show directories -@kindex show directories -Print the source path: show which directories it contains. -@end table - -If your source path is cluttered with directories that are no longer of -interest, @value{GDBN} may sometimes cause confusion by finding the wrong -versions of source. You can correct the situation as follows: - -@enumerate -@item -Use @code{directory} with no argument to reset the source path to empty. - -@item -Use @code{directory} with suitable arguments to reinstall the -directories you want in the source path. You can add all the -directories in one command. -@end enumerate - -@node Machine Code -@section Source and machine code - -You can use the command @code{info line} to map source lines to program -addresses (and vice versa), and the command @code{disassemble} to display -a range of addresses as machine instructions. - -@table @code -@item info line @var{linespec} -@kindex info line -Print the starting and ending addresses of the compiled code for -source line @var{linespec}. You can specify source lines in any of -the ways understood by the @code{list} command (@pxref{List, ,Printing -source lines}). -@end table - -For example, we can use @code{info line} to discover the location of -the object code for the first line of function -@code{m4_changequote}: - -@smallexample -(@value{GDBP}) info line m4_changecom -Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350. -@end smallexample - -@noindent -We can also inquire (using @code{*@var{addr}} as the form for -@var{linespec}) what source line covers a particular address: -@smallexample -(@value{GDBP}) info line *0x63ff -Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404. -@end smallexample - -@cindex @code{$_} and @code{info line} -After @code{info line}, the default address for the @code{x} command -is changed to the starting address of the line, so that @samp{x/i} is -sufficient to begin examining the machine code (@pxref{Memory, -,Examining memory}). Also, this address is saved as the value of the -convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience -variables}). - -@table @code -@kindex disassemble -@item disassemble -@cindex assembly instructions -@cindex instructions, assembly -@cindex machine instructions -@cindex listing machine instructions -This specialized command dumps a range of memory as machine -instructions. The default memory range is the function surrounding the -program counter of the selected frame. A single argument to this -command is a program counter value; @value{GDBN} dumps the function -surrounding this value. Two arguments specify a range of addresses -(first inclusive, second exclusive) to dump. -@end table - -@ifclear H8EXCLUSIVE -We can use @code{disassemble} to inspect the object code -range shown in the last @code{info line} example (the example -shows SPARC machine instructions): - - -@smallexample -(@value{GDBP}) disas 0x63e4 0x6404 -Dump of assembler code from 0x63e4 to 0x6404: -0x63e4 <builtin_init+5340>: ble 0x63f8 <builtin_init+5360> -0x63e8 <builtin_init+5344>: sethi %hi(0x4c00), %o0 -0x63ec <builtin_init+5348>: ld [%i1+4], %o0 -0x63f0 <builtin_init+5352>: b 0x63fc <builtin_init+5364> -0x63f4 <builtin_init+5356>: ld [%o0+4], %o0 -0x63f8 <builtin_init+5360>: or %o0, 0x1a4, %o0 -0x63fc <builtin_init+5364>: call 0x9288 <path_search> -0x6400 <builtin_init+5368>: nop -End of assembler dump. -@end smallexample -@end ifclear - -@ifset H8EXCLUSIVE -For example, here is the beginning of the output for the -disassembly of a function @code{fact}: - - -@smallexample -(@value{GDBP}) disas fact -Dump of assembler code for function fact: -to 0x808c: -0x802c <fact>: 6d f2 mov.w r2,@@-r7 -0x802e <fact+2>: 6d f3 mov.w r3,@@-r7 -0x8030 <fact+4>: 6d f6 mov.w r6,@@-r7 -0x8032 <fact+6>: 0d 76 mov.w r7,r6 -0x8034 <fact+8>: 6f 70 00 08 mov.w @@(0x8,r7),r0 -0x8038 <fact+12> 19 11 sub.w r1,r1 - . - . - . -@end smallexample -@end ifset - -@node Data -@chapter Examining Data - -@cindex printing data -@cindex examining data -@kindex print -@kindex inspect -@c "inspect" is not quite a synonym if you are using Epoch, which we do not -@c document because it is nonstandard... Under Epoch it displays in a -@c different window or something like that. -The usual way to examine data in your program is with the @code{print} -command (abbreviated @code{p}), or its synonym @code{inspect}. -@ifclear CONLY -It evaluates and prints the value of an expression of the language your -program is written in (@pxref{Languages, ,Using @value{GDBN} with Different -Languages}). -@end ifclear - -@table @code -@item print @var{exp} -@itemx print /@var{f} @var{exp} -@var{exp} is an expression (in the source language). By default the -value of @var{exp} is printed in a format appropriate to its data type; -you can choose a different format by specifying @samp{/@var{f}}, where -@var{f} is a letter specifying the format; @pxref{Output Formats,,Output -formats}. - -@item print -@itemx print /@var{f} -If you omit @var{exp}, @value{GDBN} displays the last value again (from the -@dfn{value history}; @pxref{Value History, ,Value history}). This allows you to -conveniently inspect the same value in an alternative format. -@end table - -A more low-level way of examining data is with the @code{x} command. -It examines data in memory at a specified address and prints it in a -specified format. @xref{Memory, ,Examining memory}. - -If you are interested in information about types, or about how the fields -of a struct -@ifclear CONLY -or class -@end ifclear -are declared, use the @code{ptype @var{exp}} -command rather than @code{print}. @xref{Symbols, ,Examining the Symbol Table}. - -@menu -* Expressions:: Expressions -* Variables:: Program variables -* Arrays:: Artificial arrays -* Output Formats:: Output formats -* Memory:: Examining memory -* Auto Display:: Automatic display -* Print Settings:: Print settings -* Value History:: Value history -* Convenience Vars:: Convenience variables -* Registers:: Registers -@ifclear HAVE-FLOAT -* Floating Point Hardware:: Floating point hardware -@end ifclear -@end menu - -@node Expressions -@section Expressions - -@cindex expressions -@code{print} and many other @value{GDBN} commands accept an expression and -compute its value. Any kind of constant, variable or operator defined -by the programming language you are using is valid in an expression in -@value{GDBN}. This includes conditional expressions, function calls, casts -and string constants. It unfortunately does not include symbols defined -by preprocessor @code{#define} commands. - -@ifclear CONLY -Because C is so widespread, most of the expressions shown in examples in -this manual are in C. @xref{Languages, , Using @value{GDBN} with Different -Languages}, for information on how to use expressions in other -languages. - -In this section, we discuss operators that you can use in @value{GDBN} -expressions regardless of your programming language. - -Casts are supported in all languages, not just in C, because it is so -useful to cast a number into a pointer so as to examine a structure -at that address in memory. -@c FIXME: casts supported---Mod2 true? -@end ifclear - -@value{GDBN} supports these operators in addition to those of programming -languages: - -@table @code -@item @@ -@samp{@@} is a binary operator for treating parts of memory as arrays. -@xref{Arrays, ,Artificial arrays}, for more information. - -@item :: -@samp{::} allows you to specify a variable in terms of the file or -function where it is defined. @xref{Variables, ,Program variables}. - -@item @{@var{type}@} @var{addr} -@cindex @{@var{type}@} -@cindex type casting memory -@cindex memory, viewing as typed object -@cindex casts, to view memory -Refers to an object of type @var{type} stored at address @var{addr} in -memory. @var{addr} may be any expression whose value is an integer or -pointer (but parentheses are required around binary operators, just as in -a cast). This construct is allowed regardless of what kind of data is -normally supposed to reside at @var{addr}. -@end table - -@node Variables -@section Program variables - -The most common kind of expression to use is the name of a variable -in your program. - -Variables in expressions are understood in the selected stack frame -(@pxref{Selection, ,Selecting a frame}); they must either be global -(or static) or be visible according to the scope rules of the -programming language from the point of execution in that frame. This -means that in the function - -@example -foo (a) - int a; -@{ - bar (a); - @{ - int b = test (); - bar (b); - @} -@} -@end example - -@noindent -you can examine and use the variable @code{a} whenever your program is -executing within the function @code{foo}, but you can only use or -examine the variable @code{b} while your program is executing inside -the block where @code{b} is declared. - -@cindex variable name conflict -There is an exception: you can refer to a variable or function whose -scope is a single source file even if the current execution point is not -in this file. But it is possible to have more than one such variable or -function with the same name (in different source files). If that -happens, referring to that name has unpredictable effects. If you wish, -you can specify a static variable in a particular function or file, -using the colon-colon notation: - -@cindex colon-colon -@iftex -@c info cannot cope with a :: index entry, but why deprive hard copy readers? -@kindex :: -@end iftex -@example -@var{file}::@var{variable} -@var{function}::@var{variable} -@end example - -@noindent -Here @var{file} or @var{function} is the name of the context for the -static @var{variable}. In the case of file names, you can use quotes to -make sure @value{GDBN} parses the file name as a single word---for example, -to print a global value of @code{x} defined in @file{f2.c}: - -@example -(@value{GDBP}) p 'f2.c'::x -@end example - -@ifclear CONLY -@cindex C++ scope resolution -This use of @samp{::} is very rarely in conflict with the very similar -use of the same notation in C++. @value{GDBN} also supports use of the C++ -scope resolution operator in @value{GDBN} expressions. -@c FIXME: Um, so what happens in one of those rare cases where it's in -@c conflict?? --mew -@end ifclear - -@cindex wrong values -@cindex variable values, wrong -@quotation -@emph{Warning:} Occasionally, a local variable may appear to have the -wrong value at certain points in a function---just after entry to a new -scope, and just before exit. -@end quotation -You may see this problem when you are stepping by machine instructions. -This is because on most machines, it takes more than one instruction to -set up a stack frame (including local variable definitions); if you are -stepping by machine instructions, variables may appear to have the wrong -values until the stack frame is completely built. On exit, it usually -also takes more than one machine instruction to destroy a stack frame; -after you begin stepping through that group of instructions, local -variable definitions may be gone. - -@node Arrays -@section Artificial arrays - -@cindex artificial array -@kindex @@ -It is often useful to print out several successive objects of the -same type in memory; a section of an array, or an array of -dynamically determined size for which only a pointer exists in the -program. - -You can do this by referring to a contiguous span of memory as an -@dfn{artificial array}, using the binary operator @samp{@@}. The left -operand of @samp{@@} should be the first element of the desired array, -as an individual object. The right operand should be the desired length -of the array. The result is an array value whose elements are all of -the type of the left argument. The first element is actually the left -argument; the second element comes from bytes of memory immediately -following those that hold the first element, and so on. Here is an -example. If a program says - -@example -int *array = (int *) malloc (len * sizeof (int)); -@end example - -@noindent -you can print the contents of @code{array} with - -@example -p *array@@len -@end example - -The left operand of @samp{@@} must reside in memory. Array values made -with @samp{@@} in this way behave just like other arrays in terms of -subscripting, and are coerced to pointers when used in expressions. -Artificial arrays most often appear in expressions via the value history -(@pxref{Value History, ,Value history}), after printing one out. - -Sometimes the artificial array mechanism is not quite enough; in -moderately complex data structures, the elements of interest may not -actually be adjacent---for example, if you are interested in the values -of pointers in an array. One useful work-around in this situation is -to use a convenience variable (@pxref{Convenience Vars, ,Convenience -variables}) as a counter in an expression that prints the first -interesting value, and then repeat that expression via @key{RET}. For -instance, suppose you have an array @code{dtab} of pointers to -structures, and you are interested in the values of a field @code{fv} -in each structure. Here is an example of what you might type: - -@example -set $i = 0 -p dtab[$i++]->fv -@key{RET} -@key{RET} -@dots{} -@end example - -@node Output Formats -@section Output formats - -@cindex formatted output -@cindex output formats -By default, @value{GDBN} prints a value according to its data type. Sometimes -this is not what you want. For example, you might want to print a number -in hex, or a pointer in decimal. Or you might want to view data in memory -at a certain address as a character string or as an instruction. To do -these things, specify an @dfn{output format} when you print a value. - -The simplest use of output formats is to say how to print a value -already computed. This is done by starting the arguments of the -@code{print} command with a slash and a format letter. The format -letters supported are: - -@table @code -@item x -Regard the bits of the value as an integer, and print the integer in -hexadecimal. - -@item d -Print as integer in signed decimal. - -@item u -Print as integer in unsigned decimal. - -@item o -Print as integer in octal. - -@item t -Print as integer in binary. The letter @samp{t} stands for ``two''. -@footnote{@samp{b} cannot be used because these format letters are also -used with the @code{x} command, where @samp{b} stands for ``byte''; -@pxref{Memory,,Examining memory}.} - -@item a -@cindex unknown address, locating -Print as an address, both absolute in hexadecimal and as an offset from -the nearest preceding symbol. You can use this format used to discover -where (in what function) an unknown address is located: - -@example -(@value{GDBP}) p/a 0x54320 -$3 = 0x54320 <_initialize_vx+396> -@end example - -@item c -Regard as an integer and print it as a character constant. - -@item f -Regard the bits of the value as a floating point number and print -using typical floating point syntax. -@end table - -For example, to print the program counter in hex (@pxref{Registers}), type - -@example -p/x $pc -@end example - -@noindent -Note that no space is required before the slash; this is because command -names in @value{GDBN} cannot contain a slash. - -To reprint the last value in the value history with a different format, -you can use the @code{print} command with just a format and no -expression. For example, @samp{p/x} reprints the last value in hex. - -@node Memory -@section Examining memory - -You can use the command @code{x} (for ``examine'') to examine memory in -any of several formats, independently of your program's data types. - -@cindex examining memory -@table @code -@kindex x -@item x/@var{nfu} @var{addr} -@itemx x @var{addr} -@itemx x -Use the @code{x} command to examine memory. -@end table - -@var{n}, @var{f}, and @var{u} are all optional parameters that specify how -much memory to display and how to format it; @var{addr} is an -expression giving the address where you want to start displaying memory. -If you use defaults for @var{nfu}, you need not type the slash @samp{/}. -Several commands set convenient defaults for @var{addr}. - -@table @r -@item @var{n}, the repeat count -The repeat count is a decimal integer; the default is 1. It specifies -how much memory (counting by units @var{u}) to display. -@c This really is **decimal**; unaffected by 'set radix' as of GDB -@c 4.1.2. - -@item @var{f}, the display format -The display format is one of the formats used by @code{print}, -or @samp{s} (null-terminated string) or @samp{i} (machine instruction). -The default is @samp{x} (hexadecimal) initially, or the format from the -last time you used either @code{x} or @code{print}. - -@item @var{u}, the unit size -The unit size is any of - -@table @code -@item b -Bytes. -@item h -Halfwords (two bytes). -@item w -Words (four bytes). This is the initial default. -@item g -Giant words (eight bytes). -@end table - -Each time you specify a unit size with @code{x}, that size becomes the -default unit the next time you use @code{x}. (For the @samp{s} and -@samp{i} formats, the unit size is ignored and is normally not written.) - -@item @var{addr}, starting display address -@var{addr} is the address where you want @value{GDBN} to begin displaying -memory. The expression need not have a pointer value (though it may); -it is always interpreted as an integer address of a byte of memory. -@xref{Expressions, ,Expressions}, for more information on expressions. The default for -@var{addr} is usually just after the last address examined---but several -other commands also set the default address: @code{info breakpoints} (to -the address of the last breakpoint listed), @code{info line} (to the -starting address of a line), and @code{print} (if you use it to display -a value from memory). -@end table - -For example, @samp{x/3uh 0x54320} is a request to display three halfwords -(@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}), -starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four -words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; -@pxref{Registers}) in hexadecimal (@samp{x}). - -Since the letters indicating unit sizes are all distinct from the -letters specifying output formats, you do not have to remember whether -unit size or format comes first; either order works. The output -specifications @samp{4xw} and @samp{4wx} mean exactly the same thing. -(However, the count @var{n} must come first; @samp{wx4} does not work.) - -Even though the unit size @var{u} is ignored for the formats @samp{s} -and @samp{i}, you might still want to use a count @var{n}; for example, -@samp{3i} specifies that you want to see three machine instructions, -including any operands. The command @code{disassemble} gives an -alternative way of inspecting machine instructions; @pxref{Machine -Code,,Source and machine code}. - -All the defaults for the arguments to @code{x} are designed to make it -easy to continue scanning memory with minimal specifications each time -you use @code{x}. For example, after you have inspected three machine -instructions with @samp{x/3i @var{addr}}, you can inspect the next seven -with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command, -the repeat count @var{n} is used again; the other arguments default as -for successive uses of @code{x}. - -@cindex @code{$_}, @code{$__}, and value history -The addresses and contents printed by the @code{x} command are not saved -in the value history because there is often too much of them and they -would get in the way. Instead, @value{GDBN} makes these values available for -subsequent use in expressions as values of the convenience variables -@code{$_} and @code{$__}. After an @code{x} command, the last address -examined is available for use in expressions in the convenience variable -@code{$_}. The contents of that address, as examined, are available in -the convenience variable @code{$__}. - -If the @code{x} command has a repeat count, the address and contents saved -are from the last memory unit printed; this is not the same as the last -address printed if several units were printed on the last line of output. - -@node Auto Display -@section Automatic display -@cindex automatic display -@cindex display of expressions - -If you find that you want to print the value of an expression frequently -(to see how it changes), you might want to add it to the @dfn{automatic -display list} so that @value{GDBN} prints its value each time your program stops. -Each expression added to the list is given a number to identify it; -to remove an expression from the list, you specify that number. -The automatic display looks like this: - -@example -2: foo = 38 -3: bar[5] = (struct hack *) 0x3804 -@end example - -@noindent -This display shows item numbers, expressions and their current values. As with -displays you request manually using @code{x} or @code{print}, you can -specify the output format you prefer; in fact, @code{display} decides -whether to use @code{print} or @code{x} depending on how elaborate your -format specification is---it uses @code{x} if you specify a unit size, -or one of the two formats (@samp{i} and @samp{s}) that are only -supported by @code{x}; otherwise it uses @code{print}. - -@table @code -@item display @var{exp} -@kindex display -Add the expression @var{exp} to the list of expressions to display -each time your program stops. @xref{Expressions, ,Expressions}. - -@code{display} does not repeat if you press @key{RET} again after using it. - -@item display/@var{fmt} @var{exp} -For @var{fmt} specifying only a display format and not a size or -count, add the expression @var{exp} to the auto-display list but -arrange to display it each time in the specified format @var{fmt}. -@xref{Output Formats,,Output formats}. - -@item display/@var{fmt} @var{addr} -For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a -number of units, add the expression @var{addr} as a memory address to -be examined each time your program stops. Examining means in effect -doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining memory}. -@end table - -For example, @samp{display/i $pc} can be helpful, to see the machine -instruction about to be executed each time execution stops (@samp{$pc} -is a common name for the program counter; @pxref{Registers}). - -@table @code -@item undisplay @var{dnums}@dots{} -@itemx delete display @var{dnums}@dots{} -@kindex delete display -@kindex undisplay -Remove item numbers @var{dnums} from the list of expressions to display. - -@code{undisplay} does not repeat if you press @key{RET} after using it. -(Otherwise you would just get the error @samp{No display number @dots{}}.) - -@item disable display @var{dnums}@dots{} -@kindex disable display -Disable the display of item numbers @var{dnums}. A disabled display -item is not printed automatically, but is not forgotten. It may be -enabled again later. - -@item enable display @var{dnums}@dots{} -@kindex enable display -Enable display of item numbers @var{dnums}. It becomes effective once -again in auto display of its expression, until you specify otherwise. - -@item display -Display the current values of the expressions on the list, just as is -done when your program stops. - -@item info display -@kindex info display -Print the list of expressions previously set up to display -automatically, each one with its item number, but without showing the -values. This includes disabled expressions, which are marked as such. -It also includes expressions which would not be displayed right now -because they refer to automatic variables not currently available. -@end table - -If a display expression refers to local variables, then it does not make -sense outside the lexical context for which it was set up. Such an -expression is disabled when execution enters a context where one of its -variables is not defined. For example, if you give the command -@code{display last_char} while inside a function with an argument -@code{last_char}, @value{GDBN} displays this argument while your program -continues to stop inside that function. When it stops elsewhere---where -there is no variable @code{last_char}---the display is disabled -automatically. The next time your program stops where @code{last_char} -is meaningful, you can enable the display expression once again. - -@node Print Settings -@section Print settings - -@cindex format options -@cindex print settings -@value{GDBN} provides the following ways to control how arrays, structures, -and symbols are printed. - -@noindent -These settings are useful for debugging programs in any language: - -@table @code -@item set print address -@itemx set print address on -@kindex set print address -@value{GDBN} prints memory addresses showing the location of stack -traces, structure values, pointer values, breakpoints, and so forth, -even when it also displays the contents of those addresses. The default -is @code{on}. For example, this is what a stack frame display looks like, with -@code{set print address on}: - -@smallexample -@group -(@value{GDBP}) f -#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") - at input.c:530 -530 if (lquote != def_lquote) -@end group -@end smallexample - -@item set print address off -Do not print addresses when displaying their contents. For example, -this is the same stack frame displayed with @code{set print address off}: - -@smallexample -@group -(@value{GDBP}) set print addr off -(@value{GDBP}) f -#0 set_quotes (lq="<<", rq=">>") at input.c:530 -530 if (lquote != def_lquote) -@end group -@end smallexample - -You can use @samp{set print address off} to eliminate all machine -dependent displays from the @value{GDBN} interface. For example, with -@code{print address off}, you should get the same text for backtraces on -all machines---whether or not they involve pointer arguments. - -@item show print address -@kindex show print address -Show whether or not addresses are to be printed. -@end table - -When @value{GDBN} prints a symbolic address, it normally prints the -closest earlier symbol plus an offset. If that symbol does not uniquely -identify the address (for example, it is a name whose scope is a single -source file), you may need to disambiguate. One way to do this is with -@code{info line}, for example @samp{info line *0x4537}. Alternately, -you can set @value{GDBN} to print the source file and line number when -it prints a symbolic address: - -@table @code -@item set print symbol-filename on -@kindex set print symbol-filename -Tell @value{GDBN} to print the source file name and line number of a -symbol in the symbolic form of an address. - -@item set print symbol-filename off -Do not print source file name and line number of a symbol. This is the -default. - -@item show print symbol-filename -@kindex show print symbol-filename -Show whether or not @value{GDBN} will print the source file name and -line number of a symbol in the symbolic form of an address. -@end table - -Another situation where it is helpful to show symbol filenames and line -numbers is when disassembling code; @value{GDBN} shows you the line -number and source file that corresponds to each instruction. - -Also, you may wish to see the symbolic form only if the address being -printed is reasonably close to the closest earlier symbol: - -@table @code -@item set print max-symbolic-offset @var{max-offset} -@kindex set print max-symbolic-offset -Tell @value{GDBN} to only display the symbolic form of an address if the -offset between the closest earlier symbol and the address is less than -@var{max-offset}. The default is 0, which means to always print the -symbolic form of an address, if any symbol precedes it. - -@item show print max-symbolic-offset -@kindex show print max-symbolic-offset -Ask how large the maximum offset is that @value{GDBN} prints in a -symbolic address. -@end table - -@cindex wild pointer, interpreting -@cindex pointer, finding referent -If you have a pointer and you are not sure where it points, try -@samp{set print symbol-filename on}. Then you can determine the name -and source file location of the variable where it points, using -@samp{p/a @var{pointer}}. This interprets the address in symbolic form. -For example, here @value{GDBN} shows that a variable @code{ptt} points -at another variable @code{t}, defined in @file{hi2.c}: - -@example -(@value{GDBP}) set print symbol-filename on -(@value{GDBP}) p/a ptt -$4 = 0xe008 <t in hi2.c> -@end example - -@quotation -@emph{Warning:} For pointers that point to a local variable, @samp{p/a} -does not show the symbol name and filename of the referent, even with -the appropriate @code{set print} options turned on. -@end quotation - -Other settings control how different kinds of objects are printed: - -@table @code -@item set print array -@itemx set print array on -@kindex set print array -Pretty-print arrays. This format is more convenient to read, -but uses more space. The default is off. - -@item set print array off -Return to compressed format for arrays. - -@item show print array -@kindex show print array -Show whether compressed or pretty format is selected for displaying -arrays. - -@item set print elements @var{number-of-elements} -@kindex set print elements -If @value{GDBN} is printing a large array, it stops printing after it has -printed the number of elements set by the @code{set print elements} command. -This limit also applies to the display of strings. -Setting the number of elements to zero means that the printing is unlimited. - -@item show print elements -@kindex show print elements -Display the number of elements of a large array that @value{GDBN} prints -before losing patience. - -@item set print pretty on -@kindex set print pretty -Cause @value{GDBN} to print structures in an indented format with one member per -line, like this: - -@smallexample -@group -$1 = @{ - next = 0x0, - flags = @{ - sweet = 1, - sour = 1 - @}, - meat = 0x54 "Pork" -@} -@end group -@end smallexample - -@item set print pretty off -Cause @value{GDBN} to print structures in a compact format, like this: - -@smallexample -@group -$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \ -meat = 0x54 "Pork"@} -@end group -@end smallexample - -@noindent -This is the default format. - -@item show print pretty -@kindex show print pretty -Show which format @value{GDBN} is using to print structures. - -@item set print sevenbit-strings on -@kindex set print sevenbit-strings -Print using only seven-bit characters; if this option is set, -@value{GDBN} displays any eight-bit characters (in strings or -character values) using the notation @code{\}@var{nnn}. This setting is -best if you are working in English (@sc{ascii}) and you use the -high-order bit of characters as a marker or ``meta'' bit. - -@item set print sevenbit-strings off -Print full eight-bit characters. This allows the use of more -international character sets, and is the default. - -@item show print sevenbit-strings -@kindex show print sevenbit-strings -Show whether or not @value{GDBN} is printing only seven-bit characters. - -@item set print union on -@kindex set print union -Tell @value{GDBN} to print unions which are contained in structures. This is the -default setting. - -@item set print union off -Tell @value{GDBN} not to print unions which are contained in structures. - -@item show print union -@kindex show print union -Ask @value{GDBN} whether or not it will print unions which are contained in -structures. - -For example, given the declarations - -@smallexample -typedef enum @{Tree, Bug@} Species; -typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms; -typedef enum @{Caterpillar, Cocoon, Butterfly@} - Bug_forms; - -struct thing @{ - Species it; - union @{ - Tree_forms tree; - Bug_forms bug; - @} form; -@}; - -struct thing foo = @{Tree, @{Acorn@}@}; -@end smallexample - -@noindent -with @code{set print union on} in effect @samp{p foo} would print - -@smallexample -$1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@} -@end smallexample - -@noindent -and with @code{set print union off} in effect it would print - -@smallexample -$1 = @{it = Tree, form = @{...@}@} -@end smallexample -@end table - -@ifclear CONLY -@need 1000 -@noindent -These settings are of interest when debugging C++ programs: - -@table @code -@item set print demangle -@itemx set print demangle on -@kindex set print demangle -Print C++ names in their source form rather than in the encoded -(``mangled'') form passed to the assembler and linker for type-safe -linkage. The default is @samp{on}. - -@item show print demangle -@kindex show print demangle -Show whether C++ names are printed in mangled or demangled form. - -@item set print asm-demangle -@itemx set print asm-demangle on -@kindex set print asm-demangle -Print C++ names in their source form rather than their mangled form, even -in assembler code printouts such as instruction disassemblies. -The default is off. - -@item show print asm-demangle -@kindex show print asm-demangle -Show whether C++ names in assembly listings are printed in mangled -or demangled form. - -@item set demangle-style @var{style} -@kindex set demangle-style -@cindex C++ symbol decoding style -@cindex symbol decoding style, C++ -Choose among several encoding schemes used by different compilers to -represent C++ names. The choices for @var{style} are currently: - -@table @code -@item auto -Allow @value{GDBN} to choose a decoding style by inspecting your program. - -@item gnu -Decode based on the GNU C++ compiler (@code{g++}) encoding algorithm. - -@item lucid -Decode based on the Lucid C++ compiler (@code{lcc}) encoding algorithm. - -@item arm -Decode using the algorithm in the @cite{C++ Annotated Reference Manual}. -@strong{Warning:} this setting alone is not sufficient to allow -debugging @code{cfront}-generated executables. @value{GDBN} would -require further enhancement to permit that. -@end table - -@item show demangle-style -@kindex show demangle-style -Display the encoding style currently in use for decoding C++ symbols. - -@item set print object -@itemx set print object on -@kindex set print object -When displaying a pointer to an object, identify the @emph{actual} -(derived) type of the object rather than the @emph{declared} type, using -the virtual function table. - -@item set print object off -Display only the declared type of objects, without reference to the -virtual function table. This is the default setting. - -@item show print object -@kindex show print object -Show whether actual, or declared, object types are displayed. - -@item set print vtbl -@itemx set print vtbl on -@kindex set print vtbl -Pretty print C++ virtual function tables. The default is off. - -@item set print vtbl off -Do not pretty print C++ virtual function tables. - -@item show print vtbl -@kindex show print vtbl -Show whether C++ virtual function tables are pretty printed, or not. -@end table -@end ifclear - -@node Value History -@section Value history - -@cindex value history -Values printed by the @code{print} command are saved in the @value{GDBN} @dfn{value -history} so that you can refer to them in other expressions. Values are -kept until the symbol table is re-read or discarded (for example with -the @code{file} or @code{symbol-file} commands). When the symbol table -changes, the value history is discarded, since the values may contain -pointers back to the types defined in the symbol table. - -@cindex @code{$} -@cindex @code{$$} -@cindex history number -The values printed are given @dfn{history numbers} by which you can -refer to them. These are successive integers starting with one. -@code{print} shows you the history number assigned to a value by -printing @samp{$@var{num} = } before the value; here @var{num} is the -history number. - -To refer to any previous value, use @samp{$} followed by the value's -history number. The way @code{print} labels its output is designed to -remind you of this. Just @code{$} refers to the most recent value in -the history, and @code{$$} refers to the value before that. -@code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2} -is the value just prior to @code{$$}, @code{$$1} is equivalent to -@code{$$}, and @code{$$0} is equivalent to @code{$}. - -For example, suppose you have just printed a pointer to a structure and -want to see the contents of the structure. It suffices to type - -@example -p *$ -@end example - -If you have a chain of structures where the component @code{next} points -to the next one, you can print the contents of the next one with this: - -@example -p *$.next -@end example - -@noindent -You can print successive links in the chain by repeating this -command---which you can do by just typing @key{RET}. - -Note that the history records values, not expressions. If the value of -@code{x} is 4 and you type these commands: - -@example -print x -set x=5 -@end example - -@noindent -then the value recorded in the value history by the @code{print} command -remains 4 even though the value of @code{x} has changed. - -@table @code -@kindex show values -@item show values -Print the last ten values in the value history, with their item numbers. -This is like @samp{p@ $$9} repeated ten times, except that @code{show -values} does not change the history. - -@item show values @var{n} -Print ten history values centered on history item number @var{n}. - -@item show values + -Print ten history values just after the values last printed. If no more -values are available, produces no display. -@end table - -Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the -same effect as @samp{show values +}. - -@node Convenience Vars -@section Convenience variables - -@cindex convenience variables -@value{GDBN} provides @dfn{convenience variables} that you can use within -@value{GDBN} to hold on to a value and refer to it later. These variables -exist entirely within @value{GDBN}; they are not part of your program, and -setting a convenience variable has no direct effect on further execution -of your program. That is why you can use them freely. - -Convenience variables are prefixed with @samp{$}. Any name preceded by -@samp{$} can be used for a convenience variable, unless it is one of -the predefined machine-specific register names (@pxref{Registers}). -(Value history references, in contrast, are @emph{numbers} preceded -by @samp{$}. @xref{Value History, ,Value history}.) - -You can save a value in a convenience variable with an assignment -expression, just as you would set a variable in your program. -For example: - -@example -set $foo = *object_ptr -@end example - -@noindent -would save in @code{$foo} the value contained in the object pointed to by -@code{object_ptr}. - -Using a convenience variable for the first time creates it, but its -value is @code{void} until you assign a new value. You can alter the -value with another assignment at any time. - -Convenience variables have no fixed types. You can assign a convenience -variable any type of value, including structures and arrays, even if -that variable already has a value of a different type. The convenience -variable, when used as an expression, has the type of its current value. - -@table @code -@item show convenience -@kindex show convenience -Print a list of convenience variables used so far, and their values. -Abbreviated @code{show con}. -@end table - -One of the ways to use a convenience variable is as a counter to be -incremented or a pointer to be advanced. For example, to print -a field from successive elements of an array of structures: - -@example -set $i = 0 -print bar[$i++]->contents -@i{@dots{} repeat that command by typing @key{RET}.} -@end example - -Some convenience variables are created automatically by @value{GDBN} and given -values likely to be useful. - -@table @code -@item $_ -@kindex $_ -The variable @code{$_} is automatically set by the @code{x} command to -the last address examined (@pxref{Memory, ,Examining memory}). Other -commands which provide a default address for @code{x} to examine also -set @code{$_} to that address; these commands include @code{info line} -and @code{info breakpoint}. The type of @code{$_} is @code{void *} -except when set by the @code{x} command, in which case it is a pointer -to the type of @code{$__}. - -@item $__ -@kindex $__ -The variable @code{$__} is automatically set by the @code{x} command -to the value found in the last address examined. Its type is chosen -to match the format in which the data was printed. -@end table - -@node Registers -@section Registers - -@cindex registers -You can refer to machine register contents, in expressions, as variables -with names starting with @samp{$}. The names of registers are different -for each machine; use @code{info registers} to see the names used on -your machine. - -@table @code -@item info registers -@kindex info registers -Print the names and values of all registers except floating-point -registers (in the selected stack frame). - -@item info all-registers -@kindex info all-registers -@cindex floating point registers -Print the names and values of all registers, including floating-point -registers. - -@item info registers @var{regname} @dots{} -Print the relativized value of each specified register @var{regname}. -@var{regname} may be any register name valid on the machine you are using, with -or without the initial @samp{$}. -@end table - -@value{GDBN} has four ``standard'' register names that are available (in -expressions) on most machines---whenever they do not conflict with an -architecture's canonical mnemonics for registers. The register names -@code{$pc} and @code{$sp} are used for the program counter register and -the stack pointer. @code{$fp} is used for a register that contains a -pointer to the current stack frame, and @code{$ps} is used for a -register that contains the processor status. For example, -you could print the program counter in hex with - -@example -p/x $pc -@end example - -@noindent -or print the instruction to be executed next with - -@example -x/i $pc -@end example - -@noindent -or add four to the stack pointer@footnote{This is a way of removing -one word from the stack, on machines where stacks grow downward in -memory (most machines, nowadays). This assumes that the innermost -stack frame is selected; setting @code{$sp} is not allowed when other -stack frames are selected. To pop entire frames off the stack, -regardless of machine architecture, use @code{return}; -@pxref{Returning, ,Returning from a function}.} with - -@example -set $sp += 4 -@end example - -Whenever possible, these four standard register names are available on -your machine even though the machine has different canonical mnemonics, -so long as there is no conflict. The @code{info registers} command -shows the canonical names. For example, on the SPARC, @code{info -registers} displays the processor status register as @code{$psr} but you -can also refer to it as @code{$ps}. - -@value{GDBN} always considers the contents of an ordinary register as an -integer when the register is examined in this way. Some machines have -special registers which can hold nothing but floating point; these -registers are considered to have floating point values. There is no way -to refer to the contents of an ordinary register as floating point value -(although you can @emph{print} it as a floating point value with -@samp{print/f $@var{regname}}). - -Some registers have distinct ``raw'' and ``virtual'' data formats. This -means that the data format in which the register contents are saved by -the operating system is not the same one that your program normally -sees. For example, the registers of the 68881 floating point -coprocessor are always saved in ``extended'' (raw) format, but all C -programs expect to work with ``double'' (virtual) format. In such -cases, @value{GDBN} normally works with the virtual format only (the format that -makes sense for your program), but the @code{info registers} command -prints the data in both formats. - -Normally, register values are relative to the selected stack frame -(@pxref{Selection, ,Selecting a frame}). This means that you get the -value that the register would contain if all stack frames farther in -were exited and their saved registers restored. In order to see the -true contents of hardware registers, you must select the innermost -frame (with @samp{frame 0}). - -However, @value{GDBN} must deduce where registers are saved, from the machine -code generated by your compiler. If some registers are not saved, or if -@value{GDBN} is unable to locate the saved registers, the selected stack -frame makes no difference. - -@ifset AMD29K -@table @code -@item set rstack_high_address @var{address} -@kindex set rstack_high_address -@cindex AMD 29K register stack -@cindex register stack, AMD29K -On AMD 29000 family processors, registers are saved in a separate -``register stack''. There is no way for @value{GDBN} to determine the extent -of this stack. Normally, @value{GDBN} just assumes that the stack is ``large -enough''. This may result in @value{GDBN} referencing memory locations that -do not exist. If necessary, you can get around this problem by -specifying the ending address of the register stack with the @code{set -rstack_high_address} command. The argument should be an address, which -you probably want to precede with @samp{0x} to specify in -hexadecimal. - -@item show rstack_high_address -@kindex show rstack_high_address -Display the current limit of the register stack, on AMD 29000 family -processors. -@end table -@end ifset - -@ifclear HAVE-FLOAT -@node Floating Point Hardware -@section Floating point hardware -@cindex floating point - -@c FIXME! Really host, not target? -Depending on the host machine architecture, @value{GDBN} may be able to give -you more information about the status of the floating point hardware. - -@table @code -@item info float -@kindex info float -Display hardware-dependent information about the floating -point unit. The exact contents and layout vary depending on the -floating point chip; on some platforms, @samp{info float} is not -available at all. -@end table -@c FIXME: this is a cop-out. Try to get examples, explanations. Only -@c FIXME...supported currently on arm's and 386's. Mark properly with -@c FIXME... m4 macros to isolate general statements from hardware-dep, -@c FIXME... at that point. -@end ifclear - -@ifclear CONLY -@node Languages -@chapter Using @value{GDBN} with Different Languages -@cindex languages - -@ifset MOD2 -Although programming languages generally have common aspects, they are -rarely expressed in the same manner. For instance, in ANSI C, -dereferencing a pointer @code{p} is accomplished by @code{*p}, but in -Modula-2, it is accomplished by @code{p^}. Values can also be -represented (and displayed) differently. Hex numbers in C are written -like @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}. -@end ifset - -@cindex working language -Language-specific information is built into @value{GDBN} for some languages, -allowing you to express operations like the above in your program's -native language, and allowing @value{GDBN} to output values in a manner -consistent with the syntax of your program's native language. The -language you use to build expressions, called the @dfn{working -language}, can be selected manually, or @value{GDBN} can set it -automatically. - -@menu -* Setting:: Switching between source languages -* Show:: Displaying the language -@ifset MOD2 -* Checks:: Type and range checks -@end ifset - -* Support:: Supported languages -@end menu - -@node Setting -@section Switching between source languages - -There are two ways to control the working language---either have @value{GDBN} -set it automatically, or select it manually yourself. You can use the -@code{set language} command for either purpose. On startup, @value{GDBN} -defaults to setting the language automatically. - -@menu -* Manually:: Setting the working language manually -* Automatically:: Having @value{GDBN} infer the source language -@end menu - -@node Manually -@subsection Setting the working language - -If you allow @value{GDBN} to set the language automatically, -expressions are interpreted the same way in your debugging session and -your program. - -@kindex set language -If you wish, you may set the language manually. To do this, issue the -command @samp{set language @var{lang}}, where @var{lang} is the name of -a language, such as -@ifclear MOD2 -@code{c}. -@end ifclear -@ifset MOD2 -@code{c} or @code{modula-2}. -@end ifset -For a list of the supported languages, type @samp{set language}. -@c FIXME: rms: eventually this command should be "help set language". - -@ifset MOD2 -Setting the language manually prevents @value{GDBN} from updating the working -language automatically. This can lead to confusion if you try -to debug a program when the working language is not the same as the -source language, when an expression is acceptable to both -languages---but means different things. For instance, if the current -source file were written in C, and @value{GDBN} was parsing Modula-2, a -command such as: - -@example -print a = b + c -@end example - -@noindent -might not have the effect you intended. In C, this means to add -@code{b} and @code{c} and place the result in @code{a}. The result -printed would be the value of @code{a}. In Modula-2, this means to compare -@code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value. -@end ifset - -@node Automatically -@subsection Having @value{GDBN} infer the source language - -To have @value{GDBN} set the working language automatically, use @samp{set -language local} or @samp{set language auto}. @value{GDBN} then infers the -language that a program was written in by looking at the name of its -source files, and examining their extensions: - -@table @file -@ifset MOD2 -@item *.mod -Modula-2 source file -@end ifset - -@item *.c -C source file - -@item *.C -@itemx *.cc -C++ source file -@end table - -This information is recorded for each function or procedure in a source -file. When your program stops in a frame (usually by encountering a -breakpoint), @value{GDBN} sets the working language to the language recorded -for the function in that frame. If the language for a frame is unknown -(that is, if the function or block corresponding to the frame was -defined in a source file that does not have a recognized extension), the -current working language is not changed, and @value{GDBN} issues a warning. - -This may not seem necessary for most programs, which are written -entirely in one source language. However, program modules and libraries -written in one source language can be used by a main program written in -a different source language. Using @samp{set language auto} in this -case frees you from having to set the working language manually. - -@node Show -@section Displaying the language - -The following commands help you find out which language is the -working language, and also what language source files were written in. - -@kindex show language -@kindex info frame -@kindex info source -@table @code -@item show language -Display the current working language. This is the -language you can use with commands such as @code{print} to -build and compute expressions that may involve variables in your program. - -@item info frame -Among the other information listed here (@pxref{Frame Info, ,Information -about a frame}) is the source language for this frame. This -language becomes the working language if you use an -identifier from this frame. - -@item info source -Among the other information listed here (@pxref{Symbols, ,Examining the -Symbol Table}) is the source language of this source file. -@end table - -@ifset MOD2 -@node Checks -@section Type and range checking - -@quotation -@emph{Warning:} In this release, the @value{GDBN} commands for type and range -checking are included, but they do not yet have any effect. This -section documents the intended facilities. -@end quotation -@c FIXME remove warning when type/range code added - -Some languages are designed to guard you against making seemingly common -errors through a series of compile- and run-time checks. These include -checking the type of arguments to functions and operators, and making -sure mathematical overflows are caught at run time. Checks such as -these help to ensure a program's correctness once it has been compiled -by eliminating type mismatches, and providing active checks for range -errors when your program is running. - -@value{GDBN} can check for conditions like the above if you wish. -Although @value{GDBN} does not check the statements in your program, it -can check expressions entered directly into @value{GDBN} for evaluation via -the @code{print} command, for example. As with the working language, -@value{GDBN} can also decide whether or not to check automatically based on -your program's source language. @xref{Support, ,Supported languages}, -for the default settings of supported languages. - -@menu -* Type Checking:: An overview of type checking -* Range Checking:: An overview of range checking -@end menu - -@cindex type checking -@cindex checks, type -@node Type Checking -@subsection An overview of type checking - -Some languages, such as Modula-2, are strongly typed, meaning that the -arguments to operators and functions have to be of the correct type, -otherwise an error occurs. These checks prevent type mismatch -errors from ever causing any run-time problems. For example, - -@example -1 + 2 @result{} 3 -@exdent but -@error{} 1 + 2.3 -@end example - -The second example fails because the @code{CARDINAL} 1 is not -type-compatible with the @code{REAL} 2.3. - -For expressions you use in @value{GDBN} commands, you can tell the @value{GDBN} -type checker to skip checking; to treat any mismatches as errors and -abandon the expression; or only issue warnings when type mismatches -occur, but evaluate the expression anyway. When you choose the last of -these, @value{GDBN} evaluates expressions like the second example above, but -also issues a warning. - -Even though you may turn type checking off, other type-based reasons may -prevent @value{GDBN} from evaluating an expression. For instance, @value{GDBN} does not -know how to add an @code{int} and a @code{struct foo}. These particular -type errors have nothing to do with the language in use, and usually -arise from expressions, such as the one described above, which make -little sense to evaluate anyway. - -Each language defines to what degree it is strict about type. For -instance, both Modula-2 and C require the arguments to arithmetical -operators to be numbers. In C, enumerated types and pointers can be -represented as numbers, so that they are valid arguments to mathematical -operators. @xref{Support, ,Supported languages}, for further -details on specific languages. - -@value{GDBN} provides some additional commands for controlling the type checker: - -@kindex set check -@kindex set check type -@kindex show check type -@table @code -@item set check type auto -Set type checking on or off based on the current working language. -@xref{Support, ,Supported languages}, for the default settings for -each language. - -@item set check type on -@itemx set check type off -Set type checking on or off, overriding the default setting for the -current working language. Issue a warning if the setting does not -match the language default. If any type mismatches occur in -evaluating an expression while typechecking is on, @value{GDBN} prints a -message and aborts evaluation of the expression. - -@item set check type warn -Cause the type checker to issue warnings, but to always attempt to -evaluate the expression. Evaluating the expression may still -be impossible for other reasons. For example, @value{GDBN} cannot add -numbers and structures. - -@item show type -Show the current setting of the type checker, and whether or not @value{GDBN} is -setting it automatically. -@end table - -@cindex range checking -@cindex checks, range -@node Range Checking -@subsection An overview of range checking - -In some languages (such as Modula-2), it is an error to exceed the -bounds of a type; this is enforced with run-time checks. Such range -checking is meant to ensure program correctness by making sure -computations do not overflow, or indices on an array element access do -not exceed the bounds of the array. - -For expressions you use in @value{GDBN} commands, you can tell -@value{GDBN} to treat range errors in one of three ways: ignore them, -always treat them as errors and abandon the expression, or issue -warnings but evaluate the expression anyway. - -A range error can result from numerical overflow, from exceeding an -array index bound, or when you type a constant that is not a member -of any type. Some languages, however, do not treat overflows as an -error. In many implementations of C, mathematical overflow causes the -result to ``wrap around'' to lower values---for example, if @var{m} is -the largest integer value, and @var{s} is the smallest, then - -@example -@var{m} + 1 @result{} @var{s} -@end example - -This, too, is specific to individual languages, and in some cases -specific to individual compilers or machines. @xref{Support, , -Supported languages}, for further details on specific languages. - -@value{GDBN} provides some additional commands for controlling the range checker: - -@kindex set check -@kindex set check range -@kindex show check range -@table @code -@item set check range auto -Set range checking on or off based on the current working language. -@xref{Support, ,Supported languages}, for the default settings for -each language. - -@item set check range on -@itemx set check range off -Set range checking on or off, overriding the default setting for the -current working language. A warning is issued if the setting does not -match the language default. If a range error occurs, then a message -is printed and evaluation of the expression is aborted. - -@item set check range warn -Output messages when the @value{GDBN} range checker detects a range error, -but attempt to evaluate the expression anyway. Evaluating the -expression may still be impossible for other reasons, such as accessing -memory that the process does not own (a typical example from many Unix -systems). - -@item show range -Show the current setting of the range checker, and whether or not it is -being set automatically by @value{GDBN}. -@end table -@end ifset - -@node Support -@section Supported languages - -@ifset MOD2 -@value{GDBN} 4 supports C, C++, and Modula-2. -@end ifset -@ifclear MOD2 -@value{GDBN} 4 supports C, and C++. -@end ifclear -Some @value{GDBN} features may be used in expressions regardless of the -language you use: the @value{GDBN} @code{@@} and @code{::} operators, -and the @samp{@{type@}addr} construct (@pxref{Expressions, -,Expressions}) can be used with the constructs of any supported -language. - -The following sections detail to what degree each source language is -supported by @value{GDBN}. These sections are not meant to be language -tutorials or references, but serve only as a reference guide to what the -@value{GDBN} expression parser accepts, and what input and output -formats should look like for different languages. There are many good -books written on each of these languages; please look to these for a -language reference or tutorial. - -@ifset MOD2 -@menu -* C:: C and C++ -* Modula-2:: Modula-2 -@end menu - -@node C -@subsection C and C++ -@cindex C and C++ -@cindex expressions in C or C++ - -Since C and C++ are so closely related, many features of @value{GDBN} apply -to both languages. Whenever this is the case, we discuss both languages -together. -@end ifset -@ifclear MOD2 -@c Cancel this below, under same condition, at end of this chapter! -@raisesections -@end ifclear - -@cindex C++ -@kindex g++ -@cindex GNU C++ -The C++ debugging facilities are jointly implemented by the GNU C++ -compiler and @value{GDBN}. Therefore, to debug your C++ code -effectively, you must compile your C++ programs with the GNU C++ -compiler, @code{g++}. - -For best results when debugging C++ programs, use the stabs debugging -format. You can select that format explicitly with the @code{g++} -command-line options @samp{-gstabs} or @samp{-gstabs+}. See -@ref{Debugging Options,,Options for Debugging Your Program or GNU CC, -gcc.info, Using GNU CC}, for more information. -@end ifclear -@ifset CONLY -@node C -@chapter C Language Support -@cindex C language -@cindex expressions in C - -Information specific to the C language is built into @value{GDBN} so that you -can use C expressions while degugging. This also permits @value{GDBN} to -output values in a manner consistent with C conventions. - -@menu -* C Operators:: C operators -* C Constants:: C constants -* Debugging C:: @value{GDBN} and C -@end menu -@end ifset -@ifclear CONLY -@menu -* C Operators:: C and C++ operators -* C Constants:: C and C++ constants -* Cplus expressions:: C++ expressions -* C Defaults:: Default settings for C and C++ -@ifset MOD2 -* C Checks:: C and C++ type and range checks -@end ifset - -* Debugging C:: @value{GDBN} and C -* Debugging C plus plus:: Special features for C++ -@end menu -@end ifclear - -@ifclear CONLY -@cindex C and C++ operators -@node C Operators -@subsubsection C and C++ operators -@end ifclear -@ifset CONLY -@cindex C operators -@node C Operators -@section C operators -@end ifset - -Operators must be defined on values of specific types. For instance, -@code{+} is defined on numbers, but not on structures. Operators are -often defined on groups of types. - -@ifclear CONLY -For the purposes of C and C++, the following definitions hold: -@end ifclear - -@itemize @bullet -@item -@emph{Integral types} include @code{int} with any of its storage-class -specifiers; @code{char}; and @code{enum}. - -@item -@emph{Floating-point types} include @code{float} and @code{double}. - -@item -@emph{Pointer types} include all types defined as @code{(@var{type} -*)}. - -@item -@emph{Scalar types} include all of the above. -@end itemize - -@noindent -The following operators are supported. They are listed here -in order of increasing precedence: - -@table @code -@item , -The comma or sequencing operator. Expressions in a comma-separated list -are evaluated from left to right, with the result of the entire -expression being the last expression evaluated. - -@item = -Assignment. The value of an assignment expression is the value -assigned. Defined on scalar types. - -@item @var{op}= -Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}}, -and translated to @w{@code{@var{a} = @var{a op b}}}. -@w{@code{@var{op}=}} and @code{=} have the same precendence. -@var{op} is any one of the operators @code{|}, @code{^}, @code{&}, -@code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}. - -@item ?: -The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought -of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an -integral type. - -@item || -Logical @sc{or}. Defined on integral types. - -@item && -Logical @sc{and}. Defined on integral types. - -@item | -Bitwise @sc{or}. Defined on integral types. - -@item ^ -Bitwise exclusive-@sc{or}. Defined on integral types. - -@item & -Bitwise @sc{and}. Defined on integral types. - -@item ==@r{, }!= -Equality and inequality. Defined on scalar types. The value of these -expressions is 0 for false and non-zero for true. - -@item <@r{, }>@r{, }<=@r{, }>= -Less than, greater than, less than or equal, greater than or equal. -Defined on scalar types. The value of these expressions is 0 for false -and non-zero for true. - -@item <<@r{, }>> -left shift, and right shift. Defined on integral types. - -@item @@ -The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). - -@item +@r{, }- -Addition and subtraction. Defined on integral types, floating-point types and -pointer types. - -@item *@r{, }/@r{, }% -Multiplication, division, and modulus. Multiplication and division are -defined on integral and floating-point types. Modulus is defined on -integral types. - -@item ++@r{, }-- -Increment and decrement. When appearing before a variable, the -operation is performed before the variable is used in an expression; -when appearing after it, the variable's value is used before the -operation takes place. - -@item * -Pointer dereferencing. Defined on pointer types. Same precedence as -@code{++}. - -@item & -Address operator. Defined on variables. Same precedence as @code{++}. - -@ifclear CONLY -For debugging C++, @value{GDBN} implements a use of @samp{&} beyond what is -allowed in the C++ language itself: you can use @samp{&(&@var{ref})} -(or, if you prefer, simply @samp{&&@var{ref}}) to examine the address -where a C++ reference variable (declared with @samp{&@var{ref}}) is -stored. -@end ifclear - -@item - -Negative. Defined on integral and floating-point types. Same -precedence as @code{++}. - -@item ! -Logical negation. Defined on integral types. Same precedence as -@code{++}. - -@item ~ -Bitwise complement operator. Defined on integral types. Same precedence as -@code{++}. - - -@item .@r{, }-> -Structure member, and pointer-to-structure member. For convenience, -@value{GDBN} regards the two as equivalent, choosing whether to dereference a -pointer based on the stored type information. -Defined on @code{struct} and @code{union} data. - -@item [] -Array indexing. @code{@var{a}[@var{i}]} is defined as -@code{*(@var{a}+@var{i})}. Same precedence as @code{->}. - -@item () -Function parameter list. Same precedence as @code{->}. - -@ifclear CONLY -@item :: -C++ scope resolution operator. Defined on -@code{struct}, @code{union}, and @code{class} types. -@end ifclear - -@item :: -Doubled colons -@ifclear CONLY -also -@end ifclear -represent the @value{GDBN} scope operator (@pxref{Expressions, -,Expressions}). -@ifclear CONLY -Same precedence as @code{::}, above. -@end ifclear -@end table - -@ifclear CONLY -@cindex C and C++ constants -@node C Constants -@subsubsection C and C++ constants - -@value{GDBN} allows you to express the constants of C and C++ in the -following ways: -@end ifclear -@ifset CONLY -@cindex C constants -@node C Constants -@section C constants - -@value{GDBN} allows you to express the constants of C in the -following ways: -@end ifset - -@itemize @bullet -@item -Integer constants are a sequence of digits. Octal constants are -specified by a leading @samp{0} (ie. zero), and hexadecimal constants by -a leading @samp{0x} or @samp{0X}. Constants may also end with a letter -@samp{l}, specifying that the constant should be treated as a -@code{long} value. - -@item -Floating point constants are a sequence of digits, followed by a decimal -point, followed by a sequence of digits, and optionally followed by an -exponent. An exponent is of the form: -@samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another -sequence of digits. The @samp{+} is optional for positive exponents. - -@item -Enumerated constants consist of enumerated identifiers, or their -integral equivalents. - -@item -Character constants are a single character surrounded by single quotes -(@code{'}), or a number---the ordinal value of the corresponding character -(usually its @sc{ASCII} value). Within quotes, the single character may -be represented by a letter or by @dfn{escape sequences}, which are of -the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation -of the character's ordinal value; or of the form @samp{\@var{x}}, where -@samp{@var{x}} is a predefined special character---for example, -@samp{\n} for newline. - -@item -String constants are a sequence of character constants surrounded -by double quotes (@code{"}). - -@item -Pointer constants are an integral value. You can also write pointers -to constants using the C operator @samp{&}. - -@item -Array constants are comma-separated lists surrounded by braces @samp{@{} -and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of -integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array, -and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers. -@end itemize - -@ifclear CONLY -@node Cplus expressions -@subsubsection C++ expressions - -@cindex expressions in C++ -@value{GDBN} expression handling has a number of extensions to -interpret a significant subset of C++ expressions. - -@cindex C++ support, not in @sc{coff} -@cindex @sc{coff} versus C++ -@cindex C++ and object formats -@cindex object formats and C++ -@cindex a.out and C++ -@cindex @sc{ecoff} and C++ -@cindex @sc{xcoff} and C++ -@cindex @sc{elf}/stabs and C++ -@cindex @sc{elf}/@sc{dwarf} and C++ -@c FIXME!! GDB may eventually be able to debug C++ using DWARF; check -@c periodically whether this has happened... -@quotation -@emph{Warning:} @value{GDBN} can only debug C++ code if you compile with -the GNU C++ compiler. Moreover, C++ debugging depends on the use of -additional debugging information in the symbol table, and thus requires -special support. @value{GDBN} has this support @emph{only} with the -stabs debug format. In particular, if your compiler generates a.out, -MIPS @sc{ecoff}, RS/6000 @sc{xcoff}, or @sc{elf} with stabs extensions -to the symbol table, these facilities are all available. (With GNU CC, -you can use the @samp{-gstabs} option to request stabs debugging -extensions explicitly.) Where the object code format is standard -@sc{coff} or @sc{dwarf} in @sc{elf}, on the other hand, most of the C++ -support in @value{GDBN} does @emph{not} work. -@end quotation - -@enumerate - -@cindex member functions -@item -Member function calls are allowed; you can use expressions like - -@example -count = aml->GetOriginal(x, y) -@end example - -@kindex this -@cindex namespace in C++ -@item -While a member function is active (in the selected stack frame), your -expressions have the same namespace available as the member function; -that is, @value{GDBN} allows implicit references to the class instance -pointer @code{this} following the same rules as C++. - -@cindex call overloaded functions -@cindex type conversions in C++ -@item -You can call overloaded functions; @value{GDBN} resolves the function -call to the right definition, with one restriction---you must use -arguments of the type required by the function that you want to call. -@value{GDBN} does not perform conversions requiring constructors or -user-defined type operators. - -@cindex reference declarations -@item -@value{GDBN} understands variables declared as C++ references; you can use them in -expressions just as you do in C++ source---they are automatically -dereferenced. - -In the parameter list shown when @value{GDBN} displays a frame, the values of -reference variables are not displayed (unlike other variables); this -avoids clutter, since references are often used for large structures. -The @emph{address} of a reference variable is always shown, unless -you have specified @samp{set print address off}. - -@item -@value{GDBN} supports the C++ name resolution operator @code{::}---your -expressions can use it just as expressions in your program do. Since -one scope may be defined in another, you can use @code{::} repeatedly if -necessary, for example in an expression like -@samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows -resolving name scope by reference to source files, in both C and C++ -debugging (@pxref{Variables, ,Program variables}). -@end enumerate - -@node C Defaults -@subsubsection C and C++ defaults -@cindex C and C++ defaults - -If you allow @value{GDBN} to set type and range checking automatically, they -both default to @code{off} whenever the working language changes to -C or C++. This happens regardless of whether you, or @value{GDBN}, -selected the working language. - -If you allow @value{GDBN} to set the language automatically, it sets the -working language to C or C++ on entering code compiled from a source file -whose name ends with @file{.c}, @file{.C}, or @file{.cc}. -@xref{Automatically, ,Having @value{GDBN} infer the source language}, for -further details. - -@ifset MOD2 -@c Type checking is (a) primarily motivated by Modula-2, and (b) -@c unimplemented. If (b) changes, it might make sense to let this node -@c appear even if Mod-2 does not, but meanwhile ignore it. pesch 16jul93. -@node C Checks -@subsubsection C and C++ type and range checks -@cindex C and C++ checks - -By default, when @value{GDBN} parses C or C++ expressions, type checking -is not used. However, if you turn type checking on, @value{GDBN} -considers two variables type equivalent if: - -@itemize @bullet -@item -The two variables are structured and have the same structure, union, or -enumerated tag. - -@item -Two two variables have the same type name, or types that have been -declared equivalent through @code{typedef}. - -@ignore -@c leaving this out because neither J Gilmore nor R Pesch understand it. -@c FIXME--beers? -@item -The two @code{struct}, @code{union}, or @code{enum} variables are -declared in the same declaration. (Note: this may not be true for all C -compilers.) -@end ignore -@end itemize - -Range checking, if turned on, is done on mathematical operations. Array -indices are not checked, since they are often used to index a pointer -that is not itself an array. -@end ifset -@end ifclear - -@ifclear CONLY -@node Debugging C -@subsubsection @value{GDBN} and C -@end ifclear -@ifset CONLY -@node Debugging C -@section @value{GDBN} and C -@end ifset - -The @code{set print union} and @code{show print union} commands apply to -the @code{union} type. When set to @samp{on}, any @code{union} that is -inside a @code{struct} -@ifclear CONLY -or @code{class} -@end ifclear -is also printed. -Otherwise, it appears as @samp{@{...@}}. - -The @code{@@} operator aids in the debugging of dynamic arrays, formed -with pointers and a memory allocation function. @xref{Expressions, -,Expressions}. - -@ifclear CONLY -@node Debugging C plus plus -@subsubsection @value{GDBN} features for C++ - -@cindex commands for C++ -Some @value{GDBN} commands are particularly useful with C++, and some are -designed specifically for use with C++. Here is a summary: - -@table @code -@cindex break in overloaded functions -@item @r{breakpoint menus} -When you want a breakpoint in a function whose name is overloaded, -@value{GDBN} breakpoint menus help you specify which function definition -you want. @xref{Breakpoint Menus,,Breakpoint menus}. - -@cindex overloading in C++ -@item rbreak @var{regex} -Setting breakpoints using regular expressions is helpful for setting -breakpoints on overloaded functions that are not members of any special -classes. -@xref{Set Breaks, ,Setting breakpoints}. - -@cindex C++ exception handling -@item catch @var{exceptions} -@itemx info catch -Debug C++ exception handling using these commands. @xref{Exception -Handling, ,Breakpoints and exceptions}. - -@cindex inheritance -@item ptype @var{typename} -Print inheritance relationships as well as other information for type -@var{typename}. -@xref{Symbols, ,Examining the Symbol Table}. - -@cindex C++ symbol display -@item set print demangle -@itemx show print demangle -@itemx set print asm-demangle -@itemx show print asm-demangle -Control whether C++ symbols display in their source form, both when -displaying code as C++ source and when displaying disassemblies. -@xref{Print Settings, ,Print settings}. - -@item set print object -@itemx show print object -Choose whether to print derived (actual) or declared types of objects. -@xref{Print Settings, ,Print settings}. - -@item set print vtbl -@itemx show print vtbl -Control the format for printing virtual function tables. -@xref{Print Settings, ,Print settings}. - -@item @r{Overloaded symbol names} -You can specify a particular definition of an overloaded symbol, using -the same notation that is used to declare such symbols in C++: type -@code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can -also use the @value{GDBN} command-line word completion facilities to list the -available choices, or to finish the type list for you. -@xref{Completion,, Command completion}, for details on how to do this. -@end table -@ifclear MOD2 -@c cancels "raisesections" under same conditions near bgn of chapter -@lowersections -@end ifclear - -@ifset MOD2 -@node Modula-2 -@subsection Modula-2 -@cindex Modula-2 - -The extensions made to @value{GDBN} to support Modula-2 only support -output from the GNU Modula-2 compiler (which is currently being -developed). Other Modula-2 compilers are not currently supported, and -attempting to debug executables produced by them is most likely -to give an error as @value{GDBN} reads in the executable's symbol -table. - -@cindex expressions in Modula-2 -@menu -* M2 Operators:: Built-in operators -* Built-In Func/Proc:: Built-in functions and procedures -* M2 Constants:: Modula-2 constants -* M2 Defaults:: Default settings for Modula-2 -* Deviations:: Deviations from standard Modula-2 -* M2 Checks:: Modula-2 type and range checks -* M2 Scope:: The scope operators @code{::} and @code{.} -* GDB/M2:: @value{GDBN} and Modula-2 -@end menu - -@node M2 Operators -@subsubsection Operators -@cindex Modula-2 operators - -Operators must be defined on values of specific types. For instance, -@code{+} is defined on numbers, but not on structures. Operators are -often defined on groups of types. For the purposes of Modula-2, the -following definitions hold: - -@itemize @bullet - -@item -@emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and -their subranges. - -@item -@emph{Character types} consist of @code{CHAR} and its subranges. - -@item -@emph{Floating-point types} consist of @code{REAL}. - -@item -@emph{Pointer types} consist of anything declared as @code{POINTER TO -@var{type}}. - -@item -@emph{Scalar types} consist of all of the above. - -@item -@emph{Set types} consist of @code{SET} and @code{BITSET} types. - -@item -@emph{Boolean types} consist of @code{BOOLEAN}. -@end itemize - -@noindent -The following operators are supported, and appear in order of -increasing precedence: - -@table @code -@item , -Function argument or array index separator. - -@item := -Assignment. The value of @var{var} @code{:=} @var{value} is -@var{value}. - -@item <@r{, }> -Less than, greater than on integral, floating-point, or enumerated -types. - -@item <=@r{, }>= -Less than, greater than, less than or equal to, greater than or equal to -on integral, floating-point and enumerated types, or set inclusion on -set types. Same precedence as @code{<}. - -@item =@r{, }<>@r{, }# -Equality and two ways of expressing inequality, valid on scalar types. -Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is -available for inequality, since @code{#} conflicts with the script -comment character. - -@item IN -Set membership. Defined on set types and the types of their members. -Same precedence as @code{<}. - -@item OR -Boolean disjunction. Defined on boolean types. - -@item AND@r{, }& -Boolean conjuction. Defined on boolean types. - -@item @@ -The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). - -@item +@r{, }- -Addition and subtraction on integral and floating-point types, or union -and difference on set types. - -@item * -Multiplication on integral and floating-point types, or set intersection -on set types. - -@item / -Division on floating-point types, or symmetric set difference on set -types. Same precedence as @code{*}. - -@item DIV@r{, }MOD -Integer division and remainder. Defined on integral types. Same -precedence as @code{*}. - -@item - -Negative. Defined on @code{INTEGER} and @code{REAL} data. - -@item ^ -Pointer dereferencing. Defined on pointer types. - -@item NOT -Boolean negation. Defined on boolean types. Same precedence as -@code{^}. - -@item . -@code{RECORD} field selector. Defined on @code{RECORD} data. Same -precedence as @code{^}. - -@item [] -Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}. - -@item () -Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence -as @code{^}. - -@item ::@r{, }. -@value{GDBN} and Modula-2 scope operators. -@end table - -@quotation -@emph{Warning:} Sets and their operations are not yet supported, so @value{GDBN} -treats the use of the operator @code{IN}, or the use of operators -@code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#}, -@code{<=}, and @code{>=} on sets as an error. -@end quotation - -@cindex Modula-2 built-ins -@node Built-In Func/Proc -@subsubsection Built-in functions and procedures - -Modula-2 also makes available several built-in procedures and functions. -In describing these, the following metavariables are used: - -@table @var - -@item a -represents an @code{ARRAY} variable. - -@item c -represents a @code{CHAR} constant or variable. - -@item i -represents a variable or constant of integral type. - -@item m -represents an identifier that belongs to a set. Generally used in the -same function with the metavariable @var{s}. The type of @var{s} should -be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}). - -@item n -represents a variable or constant of integral or floating-point type. - -@item r -represents a variable or constant of floating-point type. - -@item t -represents a type. - -@item v -represents a variable. - -@item x -represents a variable or constant of one of many types. See the -explanation of the function for details. -@end table - -All Modula-2 built-in procedures also return a result, described below. - -@table @code -@item ABS(@var{n}) -Returns the absolute value of @var{n}. - -@item CAP(@var{c}) -If @var{c} is a lower case letter, it returns its upper case -equivalent, otherwise it returns its argument - -@item CHR(@var{i}) -Returns the character whose ordinal value is @var{i}. - -@item DEC(@var{v}) -Decrements the value in the variable @var{v}. Returns the new value. - -@item DEC(@var{v},@var{i}) -Decrements the value in the variable @var{v} by @var{i}. Returns the -new value. - -@item EXCL(@var{m},@var{s}) -Removes the element @var{m} from the set @var{s}. Returns the new -set. - -@item FLOAT(@var{i}) -Returns the floating point equivalent of the integer @var{i}. - -@item HIGH(@var{a}) -Returns the index of the last member of @var{a}. - -@item INC(@var{v}) -Increments the value in the variable @var{v}. Returns the new value. - -@item INC(@var{v},@var{i}) -Increments the value in the variable @var{v} by @var{i}. Returns the -new value. - -@item INCL(@var{m},@var{s}) -Adds the element @var{m} to the set @var{s} if it is not already -there. Returns the new set. - -@item MAX(@var{t}) -Returns the maximum value of the type @var{t}. - -@item MIN(@var{t}) -Returns the minimum value of the type @var{t}. - -@item ODD(@var{i}) -Returns boolean TRUE if @var{i} is an odd number. - -@item ORD(@var{x}) -Returns the ordinal value of its argument. For example, the ordinal -value of a character is its ASCII value (on machines supporting the -ASCII character set). @var{x} must be of an ordered type, which include -integral, character and enumerated types. - -@item SIZE(@var{x}) -Returns the size of its argument. @var{x} can be a variable or a type. - -@item TRUNC(@var{r}) -Returns the integral part of @var{r}. - -@item VAL(@var{t},@var{i}) -Returns the member of the type @var{t} whose ordinal value is @var{i}. -@end table - -@quotation -@emph{Warning:} Sets and their operations are not yet supported, so -@value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as -an error. -@end quotation - -@cindex Modula-2 constants -@node M2 Constants -@subsubsection Constants - -@value{GDBN} allows you to express the constants of Modula-2 in the following -ways: - -@itemize @bullet - -@item -Integer constants are simply a sequence of digits. When used in an -expression, a constant is interpreted to be type-compatible with the -rest of the expression. Hexadecimal integers are specified by a -trailing @samp{H}, and octal integers by a trailing @samp{B}. - -@item -Floating point constants appear as a sequence of digits, followed by a -decimal point and another sequence of digits. An optional exponent can -then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where -@samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the -digits of the floating point constant must be valid decimal (base 10) -digits. - -@item -Character constants consist of a single character enclosed by a pair of -like quotes, either single (@code{'}) or double (@code{"}). They may -also be expressed by their ordinal value (their ASCII value, usually) -followed by a @samp{C}. - -@item -String constants consist of a sequence of characters enclosed by a -pair of like quotes, either single (@code{'}) or double (@code{"}). -Escape sequences in the style of C are also allowed. @xref{C -Constants, ,C and C++ constants}, for a brief explanation of escape -sequences. - -@item -Enumerated constants consist of an enumerated identifier. - -@item -Boolean constants consist of the identifiers @code{TRUE} and -@code{FALSE}. - -@item -Pointer constants consist of integral values only. - -@item -Set constants are not yet supported. -@end itemize - -@node M2 Defaults -@subsubsection Modula-2 defaults -@cindex Modula-2 defaults - -If type and range checking are set automatically by @value{GDBN}, they -both default to @code{on} whenever the working language changes to -Modula-2. This happens regardless of whether you, or @value{GDBN}, -selected the working language. - -If you allow @value{GDBN} to set the language automatically, then entering -code compiled from a file whose name ends with @file{.mod} sets the -working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} set -the language automatically}, for further details. - -@node Deviations -@subsubsection Deviations from standard Modula-2 -@cindex Modula-2, deviations from - -A few changes have been made to make Modula-2 programs easier to debug. -This is done primarily via loosening its type strictness: - -@itemize @bullet -@item -Unlike in standard Modula-2, pointer constants can be formed by -integers. This allows you to modify pointer variables during -debugging. (In standard Modula-2, the actual address contained in a -pointer variable is hidden from you; it can only be modified -through direct assignment to another pointer variable or expression that -returned a pointer.) - -@item -C escape sequences can be used in strings and characters to represent -non-printable characters. @value{GDBN} prints out strings with these -escape sequences embedded. Single non-printable characters are -printed using the @samp{CHR(@var{nnn})} format. - -@item -The assignment operator (@code{:=}) returns the value of its right-hand -argument. - -@item -All built-in procedures both modify @emph{and} return their argument. -@end itemize - -@node M2 Checks -@subsubsection Modula-2 type and range checks -@cindex Modula-2 checks - -@quotation -@emph{Warning:} in this release, @value{GDBN} does not yet perform type or -range checking. -@end quotation -@c FIXME remove warning when type/range checks added - -@value{GDBN} considers two Modula-2 variables type equivalent if: - -@itemize @bullet -@item -They are of types that have been declared equivalent via a @code{TYPE -@var{t1} = @var{t2}} statement - -@item -They have been declared on the same line. (Note: This is true of the -GNU Modula-2 compiler, but it may not be true of other compilers.) -@end itemize - -As long as type checking is enabled, any attempt to combine variables -whose types are not equivalent is an error. - -Range checking is done on all mathematical operations, assignment, array -index bounds, and all built-in functions and procedures. - -@node M2 Scope -@subsubsection The scope operators @code{::} and @code{.} -@cindex scope -@kindex . -@cindex colon, doubled as scope operator -@ifinfo -@kindex colon-colon -@c Info cannot handle :: but TeX can. -@end ifinfo -@iftex -@kindex :: -@end iftex - -There are a few subtle differences between the Modula-2 scope operator -(@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have -similar syntax: - -@example - -@var{module} . @var{id} -@var{scope} :: @var{id} -@end example - -@noindent -where @var{scope} is the name of a module or a procedure, -@var{module} the name of a module, and @var{id} is any declared -identifier within your program, except another module. - -Using the @code{::} operator makes @value{GDBN} search the scope -specified by @var{scope} for the identifier @var{id}. If it is not -found in the specified scope, then @value{GDBN} searches all scopes -enclosing the one specified by @var{scope}. - -Using the @code{.} operator makes @value{GDBN} search the current scope for -the identifier specified by @var{id} that was imported from the -definition module specified by @var{module}. With this operator, it is -an error if the identifier @var{id} was not imported from definition -module @var{module}, or if @var{id} is not an identifier in -@var{module}. - -@node GDB/M2 -@subsubsection @value{GDBN} and Modula-2 - -Some @value{GDBN} commands have little use when debugging Modula-2 programs. -Five subcommands of @code{set print} and @code{show print} apply -specifically to C and C++: @samp{vtbl}, @samp{demangle}, -@samp{asm-demangle}, @samp{object}, and @samp{union}. The first four -apply to C++, and the last to the C @code{union} type, which has no direct -analogue in Modula-2. - -The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available -while using any language, is not useful with Modula-2. Its -intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be -created in Modula-2 as they can in C or C++. However, because an -address can be specified by an integral constant, the construct -@samp{@{@var{type}@}@var{adrexp}} is still useful. (@pxref{Expressions, ,Expressions}) - -@cindex @code{#} in Modula-2 -In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is -interpreted as the beginning of a comment. Use @code{<>} instead. - -@end ifset -@end ifclear - -@node Symbols -@chapter Examining the Symbol Table - -The commands described in this section allow you to inquire about the -symbols (names of variables, functions and types) defined in your -program. This information is inherent in the text of your program and -does not change as your program executes. @value{GDBN} finds it in your -program's symbol table, in the file indicated when you started @value{GDBN} -(@pxref{File Options, ,Choosing files}), or by one of the -file-management commands (@pxref{Files, ,Commands to specify files}). - -@c FIXME! This might be intentionally specific to C and C++; if so, move -@c to someplace in C section of lang chapter. -@cindex symbol names -@cindex names of symbols -@cindex quoting names -Occasionally, you may need to refer to symbols that contain unusual -characters, which @value{GDBN} ordinarily treats as word delimiters. The -most frequent case is in referring to static variables in other -source files (@pxref{Variables,,Program variables}). File names -are recorded in object files as debugging symbols, but @value{GDBN} would -ordinarily parse a typical file name, like @file{foo.c}, as the three words -@samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize -@samp{foo.c} as a single symbol, enclose it in single quotes; for example, - -@example -p 'foo.c'::x -@end example - -@noindent -looks up the value of @code{x} in the scope of the file @file{foo.c}. - -@table @code -@item info address @var{symbol} -@kindex info address -Describe where the data for @var{symbol} is stored. For a register -variable, this says which register it is kept in. For a non-register -local variable, this prints the stack-frame offset at which the variable -is always stored. - -Note the contrast with @samp{print &@var{symbol}}, which does not work -at all for a register variable, and for a stack local variable prints -the exact address of the current instantiation of the variable. - -@item whatis @var{exp} -@kindex whatis -Print the data type of expression @var{exp}. @var{exp} is not -actually evaluated, and any side-effecting operations (such as -assignments or function calls) inside it do not take place. -@xref{Expressions, ,Expressions}. - -@item whatis -Print the data type of @code{$}, the last value in the value history. - -@item ptype @var{typename} -@kindex ptype -Print a description of data type @var{typename}. @var{typename} may be -the name of a type, or for C code it may have the form -@ifclear CONLY -@samp{class @var{class-name}}, -@end ifclear -@samp{struct @var{struct-tag}}, @samp{union @var{union-tag}} or -@samp{enum @var{enum-tag}}. - -@item ptype @var{exp} -@itemx ptype -Print a description of the type of expression @var{exp}. @code{ptype} -differs from @code{whatis} by printing a detailed description, instead -of just the name of the type. - -For example, for this variable declaration: - -@example -struct complex @{double real; double imag;@} v; -@end example - -@noindent -the two commands give this output: - -@example -@group -(@value{GDBP}) whatis v -type = struct complex -(@value{GDBP}) ptype v -type = struct complex @{ - double real; - double imag; -@} -@end group -@end example - -@noindent -As with @code{whatis}, using @code{ptype} without an argument refers to -the type of @code{$}, the last value in the value history. - -@item info types @var{regexp} -@itemx info types -@kindex info types -Print a brief description of all types whose name matches @var{regexp} -(or all types in your program, if you supply no argument). Each -complete typename is matched as though it were a complete line; thus, -@samp{i type value} gives information on all types in your program whose -name includes the string @code{value}, but @samp{i type ^value$} gives -information only on types whose complete name is @code{value}. - -This command differs from @code{ptype} in two ways: first, like -@code{whatis}, it does not print a detailed description; second, it -lists all source files where a type is defined. - -@item info source -@kindex info source -Show the name of the current source file---that is, the source file for -the function containing the current point of execution---and the language -it was written in. - -@item info sources -@kindex info sources -Print the names of all source files in your program for which there is -debugging information, organized into two lists: files whose symbols -have already been read, and files whose symbols will be read when needed. - -@item info functions -@kindex info functions -Print the names and data types of all defined functions. - -@item info functions @var{regexp} -Print the names and data types of all defined functions -whose names contain a match for regular expression @var{regexp}. -Thus, @samp{info fun step} finds all functions whose names -include @code{step}; @samp{info fun ^step} finds those whose names -start with @code{step}. - -@item info variables -@kindex info variables -Print the names and data types of all variables that are declared -outside of functions (i.e., excluding local variables). - -@item info variables @var{regexp} -Print the names and data types of all variables (except for local -variables) whose names contain a match for regular expression -@var{regexp}. - -@ignore -This was never implemented. -@item info methods -@itemx info methods @var{regexp} -@kindex info methods -The @code{info methods} command permits the user to examine all defined -methods within C++ program, or (with the @var{regexp} argument) a -specific set of methods found in the various C++ classes. Many -C++ classes provide a large number of methods. Thus, the output -from the @code{ptype} command can be overwhelming and hard to use. The -@code{info-methods} command filters the methods, printing only those -which match the regular-expression @var{regexp}. -@end ignore - -@item maint print symbols @var{filename} -@itemx maint print psymbols @var{filename} -@itemx maint print msymbols @var{filename} -@kindex maint print symbols -@cindex symbol dump -@kindex maint print psymbols -@cindex partial symbol dump -Write a dump of debugging symbol data into the file @var{filename}. -These commands are used to debug the @value{GDBN} symbol-reading code. Only -symbols with debugging data are included. If you use @samp{maint print -symbols}, @value{GDBN} includes all the symbols for which it has already -collected full details: that is, @var{filename} reflects symbols for -only those files whose symbols @value{GDBN} has read. You can use the -command @code{info sources} to find out which files these are. If you -use @samp{maint print psymbols} instead, the dump shows information about -symbols that @value{GDBN} only knows partially---that is, symbols defined in -files that @value{GDBN} has skimmed, but not yet read completely. Finally, -@samp{maint print msymbols} dumps just the minimal symbol information -required for each object file from which @value{GDBN} has read some symbols. -@xref{Files, ,Commands to specify files}, for a discussion of how -@value{GDBN} reads symbols (in the description of @code{symbol-file}). -@end table - -@node Altering -@chapter Altering Execution - -Once you think you have found an error in your program, you might want to -find out for certain whether correcting the apparent error would lead to -correct results in the rest of the run. You can find the answer by -experiment, using the @value{GDBN} features for altering execution of the -program. - -For example, you can store new values into variables or memory -locations, -@ifclear BARETARGET -give your program a signal, restart it -@end ifclear -@ifset BARETARGET -restart your program -@end ifset -at a different address, or even return prematurely from a function to -its caller. - -@menu -* Assignment:: Assignment to variables -* Jumping:: Continuing at a different address -@ifclear BARETARGET -* Signaling:: Giving your program a signal -@end ifclear - -* Returning:: Returning from a function -* Calling:: Calling your program's functions -* Patching:: Patching your program -@end menu - -@node Assignment -@section Assignment to variables - -@cindex assignment -@cindex setting variables -To alter the value of a variable, evaluate an assignment expression. -@xref{Expressions, ,Expressions}. For example, - -@example -print x=4 -@end example - -@noindent -stores the value 4 into the variable @code{x}, and then prints the -value of the assignment expression (which is 4). -@ifclear CONLY -@xref{Languages, ,Using @value{GDBN} with Different Languages}, for more -information on operators in supported languages. -@end ifclear - -@kindex set variable -@cindex variables, setting -If you are not interested in seeing the value of the assignment, use the -@code{set} command instead of the @code{print} command. @code{set} is -really the same as @code{print} except that the expression's value is -not printed and is not put in the value history (@pxref{Value History, -,Value history}). The expression is evaluated only for its effects. - -If the beginning of the argument string of the @code{set} command -appears identical to a @code{set} subcommand, use the @code{set -variable} command instead of just @code{set}. This command is identical -to @code{set} except for its lack of subcommands. For example, if -your program has a variable @code{width}, you get -an error if you try to set a new value with just @samp{set width=13}, -because @value{GDBN} has the command @code{set width}: - -@example -(@value{GDBP}) whatis width -type = double -(@value{GDBP}) p width -$4 = 13 -(@value{GDBP}) set width=47 -Invalid syntax in expression. -@end example - -@noindent -The invalid expression, of course, is @samp{=47}. In -order to actually set the program's variable @code{width}, use - -@example -(@value{GDBP}) set var width=47 -@end example - -@value{GDBN} allows more implicit conversions in assignments than C; you can -freely store an integer value into a pointer variable or vice versa, -and you can convert any structure to any other structure that is the -same length or shorter. -@comment FIXME: how do structs align/pad in these conversions? -@comment /pesch@cygnus.com 18dec1990 - -To store values into arbitrary places in memory, use the @samp{@{@dots{}@}} -construct to generate a value of specified type at a specified address -(@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers -to memory location @code{0x83040} as an integer (which implies a certain size -and representation in memory), and - -@example -set @{int@}0x83040 = 4 -@end example - -@noindent -stores the value 4 into that memory location. - -@node Jumping -@section Continuing at a different address - -Ordinarily, when you continue your program, you do so at the place where -it stopped, with the @code{continue} command. You can instead continue at -an address of your own choosing, with the following commands: - -@table @code -@item jump @var{linespec} -@kindex jump -Resume execution at line @var{linespec}. Execution stops again -immediately if there is a breakpoint there. @xref{List, ,Printing -source lines}, for a description of the different forms of -@var{linespec}. - -The @code{jump} command does not change the current stack frame, or -the stack pointer, or the contents of any memory location or any -register other than the program counter. If line @var{linespec} is in -a different function from the one currently executing, the results may -be bizarre if the two functions expect different patterns of arguments or -of local variables. For this reason, the @code{jump} command requests -confirmation if the specified line is not in the function currently -executing. However, even bizarre results are predictable if you are -well acquainted with the machine-language code of your program. - -@item jump *@var{address} -Resume execution at the instruction at address @var{address}. -@end table - -You can get much the same effect as the @code{jump} command by storing a -new value into the register @code{$pc}. The difference is that this -does not start your program running; it only changes the address where it -@emph{will} run when you continue. For example, - -@example -set $pc = 0x485 -@end example - -@noindent -makes the next @code{continue} command or stepping command execute at -address @code{0x485}, rather than at the address where your program stopped. -@xref{Continuing and Stepping, ,Continuing and stepping}. - -The most common occasion to use the @code{jump} command is to back up, -perhaps with more breakpoints set, over a portion of a program that has -already executed, in order to examine its execution in more detail. - -@ifclear BARETARGET -@c @group -@node Signaling -@section Giving your program a signal - -@table @code -@item signal @var{signal} -@kindex signal -Resume execution where your program stopped, but immediately give it the -signal @var{signal}. @var{signal} can be the name or the number of a -signal. For example, on many systems @code{signal 2} and @code{signal -SIGINT} are both ways of sending an interrupt signal. - -Alternatively, if @var{signal} is zero, continue execution without -giving a signal. This is useful when your program stopped on account of -a signal and would ordinary see the signal when resumed with the -@code{continue} command; @samp{signal 0} causes it to resume without a -signal. - -@code{signal} does not repeat when you press @key{RET} a second time -after executing the command. -@end table -@c @end group - -Invoking the @code{signal} command is not the same as invoking the -@code{kill} utility from the shell. Sending a signal with @code{kill} -causes @value{GDBN} to decide what to do with the signal depending on -the signal handling tables (@pxref{Signals}). The @code{signal} command -passes the signal directly to your program. - -@end ifclear - -@node Returning -@section Returning from a function - -@table @code -@item return -@itemx return @var{expression} -@cindex returning from a function -@kindex return -You can cancel execution of a function call with the @code{return} -command. If you give an -@var{expression} argument, its value is used as the function's return -value. -@end table - -When you use @code{return}, @value{GDBN} discards the selected stack frame -(and all frames within it). You can think of this as making the -discarded frame return prematurely. If you wish to specify a value to -be returned, give that value as the argument to @code{return}. - -This pops the selected stack frame (@pxref{Selection, ,Selecting a -frame}), and any other frames inside of it, leaving its caller as the -innermost remaining frame. That frame becomes selected. The -specified value is stored in the registers used for returning values -of functions. - -The @code{return} command does not resume execution; it leaves the -program stopped in the state that would exist if the function had just -returned. In contrast, the @code{finish} command (@pxref{Continuing -and Stepping, ,Continuing and stepping}) resumes execution until the -selected stack frame returns naturally. - -@node Calling -@section Calling program functions - -@cindex calling functions -@kindex call -@table @code -@item call @var{expr} -Evaluate the expression @var{expr} without displaying @code{void} -returned values. -@end table - -You can use this variant of the @code{print} command if you want to -execute a function from your program, but without cluttering the output -with @code{void} returned values. The result is printed and saved in -the value history, if it is not void. - -@node Patching -@section Patching programs -@cindex patching binaries -@cindex writing into executables -@ifclear BARETARGET -@cindex writing into corefiles -@end ifclear - -By default, @value{GDBN} opens the file containing your program's executable -code -@ifclear BARETARGET -(or the corefile) -@end ifclear -read-only. This prevents accidental alterations -to machine code; but it also prevents you from intentionally patching -your program's binary. - -If you'd like to be able to patch the binary, you can specify that -explicitly with the @code{set write} command. For example, you might -want to turn on internal debugging flags, or even to make emergency -repairs. - -@table @code -@item set write on -@itemx set write off -@kindex set write -If you specify @samp{set write on}, @value{GDBN} opens executable -@ifclear BARETARGET -and core -@end ifclear -files for both reading and writing; if you specify @samp{set write -off} (the default), @value{GDBN} opens them read-only. - -If you have already loaded a file, you must load it again (using the -@code{exec-file} -@ifclear BARETARGET -or @code{core-file} -@end ifclear -command) after changing @code{set write}, for your new setting to take -effect. - -@item show write -@kindex show write -Display whether executable files -@ifclear BARETARGET -and core files -@end ifclear -are opened for writing as well as reading. -@end table - -@node GDB Files -@chapter @value{GDBN} Files - -@value{GDBN} needs to know the file name of the program to be debugged, both in -order to read its symbol table and in order to start your program. -@ifclear BARETARGET -To debug a core dump of a previous run, you must also tell @value{GDBN} -the name of the core dump file. -@end ifclear - -@menu -* Files:: Commands to specify files -* Symbol Errors:: Errors reading symbol files -@end menu - -@node Files -@section Commands to specify files -@cindex symbol table - -@ifclear BARETARGET -@cindex core dump file -The usual way to specify executable and core dump file names is with -the command arguments given when you start @value{GDBN} (@pxref{Invocation, -,Getting In and Out of @value{GDBN}}. -@end ifclear -@ifset BARETARGET -The usual way to specify an executable file name is with -the command argument given when you start @value{GDBN}, (@pxref{Invocation, -,Getting In and Out of @value{GDBN}}. -@end ifset - -Occasionally it is necessary to change to a different file during a -@value{GDBN} session. Or you may run @value{GDBN} and forget to specify -a file you want to use. In these situations the @value{GDBN} commands -to specify new files are useful. - -@table @code -@item file @var{filename} -@cindex executable file -@kindex file -Use @var{filename} as the program to be debugged. It is read for its -symbols and for the contents of pure memory. It is also the program -executed when you use the @code{run} command. If you do not specify a -directory and the file is not found in the @value{GDBN} working directory, @value{GDBN} -uses the environment variable @code{PATH} as a list of directories to -search, just as the shell does when looking for a program to run. You -can change the value of this variable, for both @value{GDBN} and your program, -using the @code{path} command. - -On systems with memory-mapped files, an auxiliary file -@file{@var{filename}.syms} may hold symbol table information for -@var{filename}. If so, @value{GDBN} maps in the symbol table from -@file{@var{filename}.syms}, starting up more quickly. See the -descriptions of the options @samp{-mapped} and @samp{-readnow} -(available on the command line, and with the commands @code{file}, -@code{symbol-file}, or @code{add-symbol-file}), for more information. - -@item file -@code{file} with no argument makes @value{GDBN} discard any information it -has on both executable file and the symbol table. - -@item exec-file @r{[} @var{filename} @r{]} -@kindex exec-file -Specify that the program to be run (but not the symbol table) is found -in @var{filename}. @value{GDBN} searches the environment variable @code{PATH} -if necessary to locate your program. Omitting @var{filename} means to -discard information on the executable file. - -@item symbol-file @r{[} @var{filename} @r{]} -@kindex symbol-file -Read symbol table information from file @var{filename}. @code{PATH} is -searched when necessary. Use the @code{file} command to get both symbol -table and program to run from the same file. - -@code{symbol-file} with no argument clears out @value{GDBN} information on your -program's symbol table. - -The @code{symbol-file} command causes @value{GDBN} to forget the contents of its -convenience variables, the value history, and all breakpoints and -auto-display expressions. This is because they may contain pointers to -the internal data recording symbols and data types, which are part of -the old symbol table data being discarded inside @value{GDBN}. - -@code{symbol-file} does not repeat if you press @key{RET} again after -executing it once. - -When @value{GDBN} is configured for a particular environment, it -understands debugging information in whatever format is the standard -generated for that environment; you may use either a GNU compiler, or -other compilers that adhere to the local conventions. Best results are -usually obtained from GNU compilers; for example, using @code{@value{GCC}} -you can generate debugging information for optimized code. - -On some kinds of object files, the @code{symbol-file} command does not -normally read the symbol table in full right away. Instead, it scans -the symbol table quickly to find which source files and which symbols -are present. The details are read later, one source file at a time, -as they are needed. - -The purpose of this two-stage reading strategy is to make @value{GDBN} start up -faster. For the most part, it is invisible except for occasional -pauses while the symbol table details for a particular source file are -being read. (The @code{set verbose} command can turn these pauses -into messages if desired. @xref{Messages/Warnings, ,Optional warnings -and messages}.) - -We have not implemented the two-stage strategy for COFF yet. When the -symbol table is stored in COFF format, @code{symbol-file} reads the -symbol table data in full right away. - -@item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} -@itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} -@kindex readnow -@cindex reading symbols immediately -@cindex symbols, reading immediately -@kindex mapped -@cindex memory-mapped symbol file -@cindex saving symbol table -You can override the @value{GDBN} two-stage strategy for reading symbol -tables by using the @samp{-readnow} option with any of the commands that -load symbol table information, if you want to be sure @value{GDBN} has the -entire symbol table available. - -@ifclear BARETARGET -If memory-mapped files are available on your system through the -@code{mmap} system call, you can use another option, @samp{-mapped}, to -cause @value{GDBN} to write the symbols for your program into a reusable -file. Future @value{GDBN} debugging sessions map in symbol information -from this auxiliary symbol file (if the program has not changed), rather -than spending time reading the symbol table from the executable -program. Using the @samp{-mapped} option has the same effect as -starting @value{GDBN} with the @samp{-mapped} command-line option. - -You can use both options together, to make sure the auxiliary symbol -file has all the symbol information for your program. - -The auxiliary symbol file for a program called @var{myprog} is called -@samp{@var{myprog}.syms}. Once this file exists (so long as it is newer -than the corresponding executable), @value{GDBN} always attempts to use -it when you debug @var{myprog}; no special options or commands are -needed. - -The @file{.syms} file is specific to the host machine where you run -@value{GDBN}. It holds an exact image of the internal @value{GDBN} -symbol table. It cannot be shared across multiple host platforms. - -@c FIXME: for now no mention of directories, since this seems to be in -@c flux. 13mar1992 status is that in theory GDB would look either in -@c current dir or in same dir as myprog; but issues like competing -@c GDB's, or clutter in system dirs, mean that in practice right now -@c only current dir is used. FFish says maybe a special GDB hierarchy -@c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol -@c files. - -@item core-file @r{[} @var{filename} @r{]} -@kindex core -@kindex core-file -Specify the whereabouts of a core dump file to be used as the ``contents -of memory''. Traditionally, core files contain only some parts of the -address space of the process that generated them; @value{GDBN} can access the -executable file itself for other parts. - -@code{core-file} with no argument specifies that no core file is -to be used. - -Note that the core file is ignored when your program is actually running -under @value{GDBN}. So, if you have been running your program and you wish to -debug a core file instead, you must kill the subprocess in which the -program is running. To do this, use the @code{kill} command -(@pxref{Kill Process, ,Killing the child process}). -@end ifclear - -@item load @var{filename} -@kindex load -@ifset GENERIC -Depending on what remote debugging facilities are configured into -@value{GDBN}, the @code{load} command may be available. Where it exists, it -is meant to make @var{filename} (an executable) available for debugging -on the remote system---by downloading, or dynamic linking, for example. -@code{load} also records the @var{filename} symbol table in @value{GDBN}, like -the @code{add-symbol-file} command. - -If your @value{GDBN} does not have a @code{load} command, attempting to -execute it gets the error message ``@code{You can't do that when your -target is @dots{}}'' -@end ifset - -The file is loaded at whatever address is specified in the executable. -For some object file formats, you can specify the load address when you -link the program; for other formats, like a.out, the object file format -specifies a fixed address. -@c FIXME! This would be a good place for an xref to the GNU linker doc. - -@ifset VXWORKS -On VxWorks, @code{load} links @var{filename} dynamically on the -current target system as well as adding its symbols in @value{GDBN}. -@end ifset - -@ifset I960 -@cindex download to Nindy-960 -With the Nindy interface to an Intel 960 board, @code{load} -downloads @var{filename} to the 960 as well as adding its symbols in -@value{GDBN}. -@end ifset - -@ifset H8 -@cindex download to H8/300 or H8/500 -@cindex H8/300 or H8/500 download -@cindex download to Hitachi SH -@cindex Hitachi SH download -When you select remote debugging to a Hitachi SH, H8/300, or H8/500 board -(@pxref{Hitachi Remote,,@value{GDBN} and Hitachi Microprocessors}), -the @code{load} command downloads your program to the Hitachi board and also -opens it as the current executable target for @value{GDBN} on your host -(like the @code{file} command). -@end ifset - -@code{load} does not repeat if you press @key{RET} again after using it. - -@ifclear BARETARGET -@item add-symbol-file @var{filename} @var{address} -@itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]} -@kindex add-symbol-file -@cindex dynamic linking -The @code{add-symbol-file} command reads additional symbol table information -from the file @var{filename}. You would use this command when @var{filename} -has been dynamically loaded (by some other means) into the program that -is running. @var{address} should be the memory address at which the -file has been loaded; @value{GDBN} cannot figure this out for itself. -You can specify @var{address} as an expression. - -The symbol table of the file @var{filename} is added to the symbol table -originally read with the @code{symbol-file} command. You can use the -@code{add-symbol-file} command any number of times; the new symbol data thus -read keeps adding to the old. To discard all old symbol data instead, -use the @code{symbol-file} command. - -@code{add-symbol-file} does not repeat if you press @key{RET} after using it. - -You can use the @samp{-mapped} and @samp{-readnow} options just as with -the @code{symbol-file} command, to change how @value{GDBN} manages the symbol -table information for @var{filename}. -@end ifclear - -@item info files -@itemx info target -@kindex info files -@kindex info target -@code{info files} and @code{info target} are synonymous; both print -the current target (@pxref{Targets, ,Specifying a Debugging Target}), -including the -@ifclear BARETARGET -names of the executable and core dump files -@end ifclear -@ifset BARETARGET -name of the executable file -@end ifset -currently in use by @value{GDBN}, and the files from which symbols were -loaded. The command @code{help target} lists all possible targets -rather than current ones. -@end table - -All file-specifying commands allow both absolute and relative file names -as arguments. @value{GDBN} always converts the file name to an absolute file -name and remembers it that way. - -@ifclear BARETARGET -@cindex shared libraries -@value{GDBN} supports SunOS, SVr4, Irix 5, and IBM RS/6000 shared libraries. -@value{GDBN} automatically loads symbol definitions from shared libraries -when you use the @code{run} command, or when you examine a core file. -(Before you issue the @code{run} command, @value{GDBN} does not understand -references to a function in a shared library, however---unless you are -debugging a core file). -@c FIXME: some @value{GDBN} release may permit some refs to undef -@c FIXME...symbols---eg in a break cmd---assuming they are from a shared -@c FIXME...lib; check this from time to time when updating manual - -@table @code -@item info share -@itemx info sharedlibrary -@kindex info sharedlibrary -@kindex info share -Print the names of the shared libraries which are currently loaded. - -@item sharedlibrary @var{regex} -@itemx share @var{regex} -@kindex sharedlibrary -@kindex share -This is an obsolescent command; you can use it to explicitly load shared -object library symbols for files matching a Unix regular expression, but -as with files loaded automatically, it only loads shared libraries -required by your program for a core file or after typing @code{run}. If -@var{regex} is omitted all shared libraries required by your program are -loaded. -@end table -@end ifclear - -@node Symbol Errors -@section Errors reading symbol files - -While reading a symbol file, @value{GDBN} occasionally encounters problems, -such as symbol types it does not recognize, or known bugs in compiler -output. By default, @value{GDBN} does not notify you of such problems, since -they are relatively common and primarily of interest to people -debugging compilers. If you are interested in seeing information -about ill-constructed symbol tables, you can either ask @value{GDBN} to print -only one message about each such type of problem, no matter how many -times the problem occurs; or you can ask @value{GDBN} to print more messages, -to see how many times the problems occur, with the @code{set -complaints} command (@pxref{Messages/Warnings, ,Optional warnings and -messages}). - -The messages currently printed, and their meanings, include: - -@table @code -@item inner block not inside outer block in @var{symbol} - -The symbol information shows where symbol scopes begin and end -(such as at the start of a function or a block of statements). This -error indicates that an inner scope block is not fully contained -in its outer scope blocks. - -@value{GDBN} circumvents the problem by treating the inner block as if it had -the same scope as the outer block. In the error message, @var{symbol} -may be shown as ``@code{(don't know)}'' if the outer block is not a -function. - -@item block at @var{address} out of order - -The symbol information for symbol scope blocks should occur in -order of increasing addresses. This error indicates that it does not -do so. - -@value{GDBN} does not circumvent this problem, and has trouble -locating symbols in the source file whose symbols it is reading. (You -can often determine what source file is affected by specifying -@code{set verbose on}. @xref{Messages/Warnings, ,Optional warnings and -messages}.) - -@item bad block start address patched - -The symbol information for a symbol scope block has a start address -smaller than the address of the preceding source line. This is known -to occur in the SunOS 4.1.1 (and earlier) C compiler. - -@value{GDBN} circumvents the problem by treating the symbol scope block as -starting on the previous source line. - -@item bad string table offset in symbol @var{n} - -@cindex foo -Symbol number @var{n} contains a pointer into the string table which is -larger than the size of the string table. - -@value{GDBN} circumvents the problem by considering the symbol to have the -name @code{foo}, which may cause other problems if many symbols end up -with this name. - -@item unknown symbol type @code{0x@var{nn}} - -The symbol information contains new data types that @value{GDBN} does not yet -know how to read. @code{0x@var{nn}} is the symbol type of the misunderstood -information, in hexadecimal. - -@value{GDBN} circumvents the error by ignoring this symbol information. This -usually allows you to debug your program, though certain symbols -are not accessible. If you encounter such a problem and feel like -debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint on -@code{complain}, then go up to the function @code{read_dbx_symtab} and -examine @code{*bufp} to see the symbol. - -@item stub type has NULL name -@value{GDBN} could not find the full definition for -@ifclear CONLY -a struct or class. -@end ifclear -@ifset CONLY -a struct. -@end ifset - -@ifclear CONLY -@item const/volatile indicator missing (ok if using g++ v1.x), got@dots{} - -The symbol information for a C++ member function is missing some -information that recent versions of the compiler should have output -for it. -@end ifclear - -@item info mismatch between compiler and debugger - -@value{GDBN} could not parse a type specification output by the compiler. -@end table - -@node Targets -@chapter Specifying a Debugging Target -@cindex debugging target -@kindex target - -A @dfn{target} is the execution environment occupied by your program. -@ifclear BARETARGET -Often, @value{GDBN} runs in the same host environment as your program; in -that case, the debugging target is specified as a side effect when you -use the @code{file} or @code{core} commands. When you need more -flexibility---for example, running @value{GDBN} on a physically separate -host, or controlling a standalone system over a serial port or a -realtime system over a TCP/IP connection---you -@end ifclear -@ifset BARETARGET -You -@end ifset -can use the @code{target} command to specify one of the target types -configured for @value{GDBN} (@pxref{Target Commands, ,Commands for managing -targets}). - -@menu -* Active Targets:: Active targets -* Target Commands:: Commands for managing targets -* Remote:: Remote debugging -@end menu - -@node Active Targets -@section Active targets -@cindex stacking targets -@cindex active targets -@cindex multiple targets - -@ifclear BARETARGET -There are three classes of targets: processes, core files, and -executable files. @value{GDBN} can work concurrently on up to three active -targets, one in each class. This allows you to (for example) start a -process and inspect its activity without abandoning your work on a core -file. - -For example, if you execute @samp{gdb a.out}, then the executable file -@code{a.out} is the only active target. If you designate a core file as -well---presumably from a prior run that crashed and coredumped---then -@value{GDBN} has two active targets and uses them in tandem, looking -first in the corefile target, then in the executable file, to satisfy -requests for memory addresses. (Typically, these two classes of target -are complementary, since core files contain only a program's -read-write memory---variables and so on---plus machine status, while -executable files contain only the program text and initialized data.) -@end ifclear - -When you type @code{run}, your executable file becomes an active process -target as well. When a process target is active, all @value{GDBN} commands -requesting memory addresses refer to that target; addresses in an -@ifclear BARETARGET -active core file or -@end ifclear -executable file target are obscured while the process -target is active. - -@ifset BARETARGET -Use the @code{exec-file} command to select a -new executable target (@pxref{Files, ,Commands to specify -files}). -@end ifset -@ifclear BARETARGET -Use the @code{core-file} and @code{exec-file} commands to select a -new core file or executable target (@pxref{Files, ,Commands to specify -files}). To specify as a target a process that is already running, use -the @code{attach} command (@pxref{Attach, ,Debugging an -already-running process}). -@end ifclear - -@node Target Commands -@section Commands for managing targets - -@table @code -@item target @var{type} @var{parameters} -Connects the @value{GDBN} host environment to a target -@ifset BARETARGET -machine. -@end ifset -@ifclear BARETARGET -machine or process. A target is typically a protocol for talking to -debugging facilities. You use the argument @var{type} to specify the -type or protocol of the target machine. - -Further @var{parameters} are interpreted by the target protocol, but -typically include things like device names or host names to connect -with, process numbers, and baud rates. -@end ifclear - -The @code{target} command does not repeat if you press @key{RET} again -after executing the command. - -@item help target -@kindex help target -Displays the names of all targets available. To display targets -currently selected, use either @code{info target} or @code{info files} -(@pxref{Files, ,Commands to specify files}). - -@item help target @var{name} -Describe a particular target, including any parameters necessary to -select it. -@end table - -Here are some common targets (available, or not, depending on the GDB -configuration): - -@table @code -@item target exec @var{program} -@kindex target exec -An executable file. @samp{target exec @var{program}} is the same as -@samp{exec-file @var{program}}. - -@ifclear BARETARGET -@item target core @var{filename} -@kindex target core -A core dump file. @samp{target core @var{filename}} is the same as -@samp{core-file @var{filename}}. -@end ifclear - -@ifset REMOTESTUB -@item target remote @var{dev} -@kindex target remote -Remote serial target in GDB-specific protocol. The argument @var{dev} -specifies what serial device to use for the connection (e.g. -@file{/dev/ttya}). @xref{Remote, ,Remote debugging}. -@end ifset - -@ifset SIMS -@item target sim -@kindex target sim -CPU simulator. @xref{Simulator,,Simulated CPU Target}. -@end ifset - -@ifset AMD29K -@item target udi @var{keyword} -@kindex target udi -Remote AMD29K target, using the AMD UDI protocol. The @var{keyword} -argument specifies which 29K board or simulator to use. @xref{UDI29K -Remote,,The UDI protocol for AMD29K}. - -@item target amd-eb @var{dev} @var{speed} @var{PROG} -@kindex target amd-eb -@cindex AMD EB29K -Remote PC-resident AMD EB29K board, attached over serial lines. -@var{dev} is the serial device, as for @code{target remote}; -@var{speed} allows you to specify the linespeed; and @var{PROG} is the -name of the program to be debugged, as it appears to DOS on the PC. -@xref{EB29K Remote, ,The EBMON protocol for AMD29K}. - -@end ifset -@ifset H8 -@item target hms -@kindex target hms -A Hitachi SH, H8/300, or H8/500 board, attached via serial line to your host. -@ifclear H8EXCLUSIVE -@c Unix only, not currently of interest for H8-only manual -Use special commands @code{device} and @code{speed} to control the serial -line and the communications speed used. -@end ifclear -@xref{Hitachi Remote,,@value{GDBN} and Hitachi Microprocessors}. - -@end ifset -@ifset I960 -@item target nindy @var{devicename} -@kindex target nindy -An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is -the name of the serial device to use for the connection, e.g. -@file{/dev/ttya}. @xref{i960-Nindy Remote, ,@value{GDBN} with a remote i960 (Nindy)}. - -@end ifset -@ifset ST2000 -@item target st2000 @var{dev} @var{speed} -@kindex target st2000 -A Tandem ST2000 phone switch, running Tandem's STDBUG protocol. @var{dev} -is the name of the device attached to the ST2000 serial line; -@var{speed} is the communication line speed. The arguments are not used -if @value{GDBN} is configured to connect to the ST2000 using TCP or Telnet. -@xref{ST2000 Remote,,@value{GDBN} with a Tandem ST2000}. - -@end ifset -@ifset VXWORKS -@item target vxworks @var{machinename} -@kindex target vxworks -A VxWorks system, attached via TCP/IP. The argument @var{machinename} -is the target system's machine name or IP address. -@xref{VxWorks Remote, ,@value{GDBN} and VxWorks}. -@end ifset -@end table - -@ifset GENERIC -Different targets are available on different configurations of @value{GDBN}; your -configuration may have more or fewer targets. -@end ifset - -@node Remote -@section Remote debugging -@cindex remote debugging - -If you are trying to debug a program running on a machine that cannot run -GDB in the usual way, it is often useful to use remote debugging. For -example, you might use remote debugging on an operating system kernel, or on -a small system which does not have a general purpose operating system -powerful enough to run a full-featured debugger. - -Some configurations of GDB have special serial or TCP/IP interfaces -to make this work with particular debugging targets. In addition, -GDB comes with a generic serial protocol (specific to GDB, but -not specific to any particular target system) which you can use if you -write the remote stubs---the code that runs on the remote system to -communicate with GDB. - -Other remote targets may be available in your -configuration of GDB; use @code{help target} to list them. - -@ifset GENERIC -@c Text on starting up GDB in various specific cases; it goes up front -@c in manuals configured for any of those particular situations, here -@c otherwise. -@menu -@ifset REMOTESTUB -* Remote Serial:: @value{GDBN} remote serial protocol -@end ifset -@ifset I960 -* i960-Nindy Remote:: @value{GDBN} with a remote i960 (Nindy) -@end ifset -@ifset AMD29K -* UDI29K Remote:: The UDI protocol for AMD29K -* EB29K Remote:: The EBMON protocol for AMD29K -@end ifset -@ifset VXWORKS -* VxWorks Remote:: @value{GDBN} and VxWorks -@end ifset -@ifset ST2000 -* ST2000 Remote:: @value{GDBN} with a Tandem ST2000 -@end ifset -@ifset H8 -* Hitachi Remote:: @value{GDBN} and Hitachi Microprocessors -@end ifset -@ifset MIPS -* MIPS Remote:: @value{GDBN} and MIPS boards -@end ifset -@ifset SIMS -* Simulator:: Simulated CPU target -@end ifset -@end menu - -@include remote.texi -@end ifset - -@node Controlling GDB -@chapter Controlling @value{GDBN} - -You can alter the way @value{GDBN} interacts with you by using -the @code{set} command. For commands controlling how @value{GDBN} displays -data, @pxref{Print Settings, ,Print settings}; other settings are described here. - -@menu -* Prompt:: Prompt -* Editing:: Command editing -* History:: Command history -* Screen Size:: Screen size -* Numbers:: Numbers -* Messages/Warnings:: Optional warnings and messages -@end menu - -@node Prompt -@section Prompt -@cindex prompt - -@value{GDBN} indicates its readiness to read a command by printing a string -called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You -can change the prompt string with the @code{set prompt} command. For -instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change -the prompt in one of the @value{GDBN} sessions so that you can always tell which -one you are talking to. - -@table @code -@item set prompt @var{newprompt} -@kindex set prompt -Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth. -@kindex show prompt -@item show prompt -Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}} -@end table - -@node Editing -@section Command editing -@cindex readline -@cindex command line editing - -@value{GDBN} reads its input commands via the @dfn{readline} interface. This -GNU library provides consistent behavior for programs which provide a -command line interface to the user. Advantages are @code{emacs}-style -or @code{vi}-style inline editing of commands, @code{csh}-like history -substitution, and a storage and recall of command history across -debugging sessions. - -You may control the behavior of command line editing in @value{GDBN} with the -command @code{set}. - -@table @code -@kindex set editing -@cindex editing -@item set editing -@itemx set editing on -Enable command line editing (enabled by default). - -@item set editing off -Disable command line editing. - -@kindex show editing -@item show editing -Show whether command line editing is enabled. -@end table - -@node History -@section Command history - -@value{GDBN} can keep track of the commands you type during your -debugging sessions, so that you can be certain of precisely what -happened. Use these commands to manage the @value{GDBN} command -history facility. - -@table @code -@cindex history substitution -@cindex history file -@kindex set history filename -@kindex GDBHISTFILE -@item set history filename @var{fname} -Set the name of the @value{GDBN} command history file to @var{fname}. -This is the file where @value{GDBN} reads an initial command history -list, and where it writes the command history from this session when it -exits. You can access this list through history expansion or through -the history command editing characters listed below. This file defaults -to the value of the environment variable @code{GDBHISTFILE}, or to -@file{./.gdb_history} if this variable is not set. - -@cindex history save -@kindex set history save -@item set history save -@itemx set history save on -Record command history in a file, whose name may be specified with the -@code{set history filename} command. By default, this option is disabled. - -@item set history save off -Stop recording command history in a file. - -@cindex history size -@kindex set history size -@item set history size @var{size} -Set the number of commands which @value{GDBN} keeps in its history list. -This defaults to the value of the environment variable -@code{HISTSIZE}, or to 256 if this variable is not set. -@end table - -@cindex history expansion -History expansion assigns special meaning to the character @kbd{!}. -@ifset have-readline-appendices -@xref{Event Designators}. -@end ifset - -Since @kbd{!} is also the logical not operator in C, history expansion -is off by default. If you decide to enable history expansion with the -@code{set history expansion on} command, you may sometimes need to -follow @kbd{!} (when it is used as logical not, in an expression) with -a space or a tab to prevent it from being expanded. The readline -history facilities do not attempt substitution on the strings -@kbd{!=} and @kbd{!(}, even when history expansion is enabled. - -The commands to control history expansion are: - -@table @code - -@kindex set history expansion -@item set history expansion on -@itemx set history expansion -Enable history expansion. History expansion is off by default. - -@item set history expansion off -Disable history expansion. - -The readline code comes with more complete documentation of -editing and history expansion features. Users unfamiliar with @code{emacs} -or @code{vi} may wish to read it. -@ifset have-readline-appendices -@xref{Command Line Editing}. -@end ifset - -@c @group -@kindex show history -@item show history -@itemx show history filename -@itemx show history save -@itemx show history size -@itemx show history expansion -These commands display the state of the @value{GDBN} history parameters. -@code{show history} by itself displays all four states. -@c @end group -@end table - -@table @code -@kindex show commands -@item show commands -Display the last ten commands in the command history. - -@item show commands @var{n} -Print ten commands centered on command number @var{n}. - -@item show commands + -Print ten commands just after the commands last printed. -@end table - -@node Screen Size -@section Screen size -@cindex size of screen -@cindex pauses in output - -Certain commands to @value{GDBN} may produce large amounts of -information output to the screen. To help you read all of it, -@value{GDBN} pauses and asks you for input at the end of each page of -output. Type @key{RET} when you want to continue the output, or @kbd{q} -to discard the remaining output. Also, the screen width setting -determines when to wrap lines of output. Depending on what is being -printed, @value{GDBN} tries to break the line at a readable place, -rather than simply letting it overflow onto the following line. - -Normally @value{GDBN} knows the size of the screen from the termcap data base -together with the value of the @code{TERM} environment variable and the -@code{stty rows} and @code{stty cols} settings. If this is not correct, -you can override it with the @code{set height} and @code{set -width} commands: - -@table @code -@item set height @var{lpp} -@itemx show height -@itemx set width @var{cpl} -@itemx show width -@kindex set height -@kindex set width -@kindex show width -@kindex show height -These @code{set} commands specify a screen height of @var{lpp} lines and -a screen width of @var{cpl} characters. The associated @code{show} -commands display the current settings. - -If you specify a height of zero lines, @value{GDBN} does not pause during output -no matter how long the output is. This is useful if output is to a file -or to an editor buffer. - -Likewise, you can specify @samp{set width 0} to prevent @value{GDBN} -from wrapping its output. -@end table - -@node Numbers -@section Numbers -@cindex number representation -@cindex entering numbers - -You can always enter numbers in octal, decimal, or hexadecimal in @value{GDBN} by -the usual conventions: octal numbers begin with @samp{0}, decimal -numbers end with @samp{.}, and hexadecimal numbers begin with @samp{0x}. -Numbers that begin with none of these are, by default, entered in base -10; likewise, the default display for numbers---when no particular -format is specified---is base 10. You can change the default base for -both input and output with the @code{set radix} command. - -@table @code -@kindex set radix -@item set radix @var{base} -Set the default base for numeric input and display. Supported choices -for @var{base} are decimal 8, 10, or 16. @var{base} must itself be -specified either unambiguously or using the current default radix; for -example, any of - -@example -set radix 012 -set radix 10. -set radix 0xa -@end example - -@noindent -sets the base to decimal. On the other hand, @samp{set radix 10} -leaves the radix unchanged no matter what it was. - -@kindex show radix -@item show radix -Display the current default base for numeric input and display. -@end table - -@node Messages/Warnings -@section Optional warnings and messages - -By default, @value{GDBN} is silent about its inner workings. If you are running -on a slow machine, you may want to use the @code{set verbose} command. -It makes @value{GDBN} tell you when it does a lengthy internal operation, so -you will not think it has crashed. - -Currently, the messages controlled by @code{set verbose} are those -which announce that the symbol table for a source file is being read; -see @code{symbol-file} in @ref{Files, ,Commands to specify files}. - -@table @code -@kindex set verbose -@item set verbose on -Enables @value{GDBN} output of certain informational messages. - -@item set verbose off -Disables @value{GDBN} output of certain informational messages. - -@kindex show verbose -@item show verbose -Displays whether @code{set verbose} is on or off. -@end table - -By default, if @value{GDBN} encounters bugs in the symbol table of an object -file, it is silent; but if you are debugging a compiler, you may find -this information useful (@pxref{Symbol Errors, ,Errors reading symbol files}). - -@table @code -@kindex set complaints -@item set complaints @var{limit} -Permits @value{GDBN} to output @var{limit} complaints about each type of unusual -symbols before becoming silent about the problem. Set @var{limit} to -zero to suppress all complaints; set it to a large number to prevent -complaints from being suppressed. - -@kindex show complaints -@item show complaints -Displays how many symbol complaints @value{GDBN} is permitted to produce. -@end table - -By default, @value{GDBN} is cautious, and asks what sometimes seems to be a -lot of stupid questions to confirm certain commands. For example, if -you try to run a program which is already running: - -@example -(@value{GDBP}) run -The program being debugged has been started already. -Start it from the beginning? (y or n) -@end example - -If you are willing to unflinchingly face the consequences of your own -commands, you can disable this ``feature'': - -@table @code -@kindex set confirm -@cindex flinching -@cindex confirmation -@cindex stupid questions -@item set confirm off -Disables confirmation requests. - -@item set confirm on -Enables confirmation requests (the default). - -@item show confirm -@kindex show confirm -Displays state of confirmation requests. -@end table - -@c FIXME this does not really belong here. But where *does* it belong? -@cindex reloading symbols -Some systems allow individual object files that make up your program to -be replaced without stopping and restarting your program. -@ifset VXWORKS -For example, in VxWorks you can simply recompile a defective object file -and keep on running. -@end ifset -If you are running on one of these systems, you can allow @value{GDBN} to -reload the symbols for automatically relinked modules: - -@table @code -@kindex set symbol-reloading -@item set symbol-reloading on -Replace symbol definitions for the corresponding source file when an -object file with a particular name is seen again. - -@item set symbol-reloading off -Do not replace symbol definitions when re-encountering object files of -the same name. This is the default state; if you are not running on a -system that permits automatically relinking modules, you should leave -@code{symbol-reloading} off, since otherwise @value{GDBN} may discard symbols -when linking large programs, that may contain several modules (from -different directories or libraries) with the same name. - -@item show symbol-reloading -Show the current @code{on} or @code{off} setting. -@end table - -@node Sequences -@chapter Canned Sequences of Commands - -Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint -command lists}), @value{GDBN} provides two ways to store sequences of commands -for execution as a unit: user-defined commands and command files. - -@menu -* Define:: User-defined commands -* Hooks:: User-defined command hooks -* Command Files:: Command files -* Output:: Commands for controlled output -@end menu - -@node Define -@section User-defined commands - -@cindex user-defined command -A @dfn{user-defined command} is a sequence of @value{GDBN} commands to which you -assign a new name as a command. This is done with the @code{define} -command. - -@table @code -@item define @var{commandname} -@kindex define -Define a command named @var{commandname}. If there is already a command -by that name, you are asked to confirm that you want to redefine it. - -The definition of the command is made up of other @value{GDBN} command lines, -which are given following the @code{define} command. The end of these -commands is marked by a line containing @code{end}. - -@item document @var{commandname} -@kindex document -Give documentation to the user-defined command @var{commandname}. The -command @var{commandname} must already be defined. This command reads -lines of documentation just as @code{define} reads the lines of the -command definition, ending with @code{end}. After the @code{document} -command is finished, @code{help} on command @var{commandname} displays -the documentation you have specified. - -You may use the @code{document} command again to change the -documentation of a command. Redefining the command with @code{define} -does not change the documentation. - -@item help user-defined -@kindex help user-defined -List all user-defined commands, with the first line of the documentation -(if any) for each. - -@item show user -@itemx show user @var{commandname} -@kindex show user -Display the @value{GDBN} commands used to define @var{commandname} (but not its -documentation). If no @var{commandname} is given, display the -definitions for all user-defined commands. -@end table - -User-defined commands do not take arguments. When they are executed, the -commands of the definition are not printed. An error in any command -stops execution of the user-defined command. - -Commands that would ask for confirmation if used interactively proceed -without asking when used inside a user-defined command. Many @value{GDBN} commands -that normally print messages to say what they are doing omit the messages -when used in a user-defined command. - -@node Hooks -@section User-defined command hooks -@cindex command files - -You may define @emph{hooks}, which are a special kind of user-defined -command. Whenever you run the command @samp{foo}, if the user-defined -command @samp{hook-foo} exists, it is executed (with no arguments) -before that command. - -In addition, a pseudo-command, @samp{stop} exists. Defining -(@samp{hook-stop}) makes the associated commands execute every time -execution stops in your program: before breakpoint commands are run, -displays are printed, or the stack frame is printed. - -@ifclear BARETARGET -For example, to ignore @code{SIGALRM} signals while -single-stepping, but treat them normally during normal execution, -you could define: - -@example -define hook-stop -handle SIGALRM nopass -end - -define hook-run -handle SIGALRM pass -end - -define hook-continue -handle SIGLARM pass -end -@end example -@end ifclear - -You can define a hook for any single-word command in @value{GDBN}, but -not for command aliases; you should define a hook for the basic command -name, e.g. @code{backtrace} rather than @code{bt}. -@c FIXME! So how does Joe User discover whether a command is an alias -@c or not? -If an error occurs during the execution of your hook, execution of -@value{GDBN} commands stops and @value{GDBN} issues a prompt -(before the command that you actually typed had a chance to run). - -If you try to define a hook which does not match any known command, you -get a warning from the @code{define} command. - -@node Command Files -@section Command files - -@cindex command files -A command file for @value{GDBN} is a file of lines that are @value{GDBN} commands. Comments -(lines starting with @kbd{#}) may also be included. An empty line in a -command file does nothing; it does not mean to repeat the last command, as -it would from the terminal. - -@cindex init file -@cindex @file{@value{GDBINIT}} -When you start @value{GDBN}, it automatically executes commands from its -@dfn{init files}. These are files named @file{@value{GDBINIT}}. -@value{GDBN} reads the init file (if any) in your home directory, then -processes command line options and operands, and then reads the init -file (if any) in the current working directory. This is so the init -file in your home directory can set options (such as @code{set -complaints}) which affect the processing of the command line options and -operands. The init files are not executed if you use the @samp{-nx} -option; @pxref{Mode Options, ,Choosing modes}. - -@ifset GENERIC -@cindex init file name -On some configurations of @value{GDBN}, the init file is known by a -different name (these are typically environments where a specialized -form of GDB may need to coexist with other forms, hence a different name -for the specialized version's init file). These are the environments -with special init file names: - -@itemize @bullet -@kindex .vxgdbinit -@item -VxWorks (Wind River Systems real-time OS): @samp{.vxgdbinit} - -@kindex .os68gdbinit -@item -OS68K (Enea Data Systems real-time OS): @samp{.os68gdbinit} - -@kindex .esgdbinit -@item -ES-1800 (Ericsson Telecom AB M68000 emulator): @samp{.esgdbinit} -@end itemize -@end ifset - -You can also request the execution of a command file with the -@code{source} command: - -@table @code -@item source @var{filename} -@kindex source -Execute the command file @var{filename}. -@end table - -The lines in a command file are executed sequentially. They are not -printed as they are executed. An error in any command terminates execution -of the command file. - -Commands that would ask for confirmation if used interactively proceed -without asking when used in a command file. Many @value{GDBN} commands that -normally print messages to say what they are doing omit the messages -when called from command files. - -@node Output -@section Commands for controlled output - -During the execution of a command file or a user-defined command, normal -@value{GDBN} output is suppressed; the only output that appears is what is -explicitly printed by the commands in the definition. This section -describes three commands useful for generating exactly the output you -want. - -@table @code -@item echo @var{text} -@kindex echo -@c I do not consider backslash-space a standard C escape sequence -@c because it is not in ANSI. -Print @var{text}. Nonprinting characters can be included in -@var{text} using C escape sequences, such as @samp{\n} to print a -newline. @strong{No newline is printed unless you specify one.} -In addition to the standard C escape sequences, a backslash followed -by a space stands for a space. This is useful for displaying a -string with spaces at the beginning or the end, since leading and -trailing spaces are otherwise trimmed from all arguments. -To print @samp{@w{ }and foo =@w{ }}, use the command -@samp{echo \@w{ }and foo = \@w{ }}. - -A backslash at the end of @var{text} can be used, as in C, to continue -the command onto subsequent lines. For example, - -@example -echo This is some text\n\ -which is continued\n\ -onto several lines.\n -@end example - -produces the same output as - -@example -echo This is some text\n -echo which is continued\n -echo onto several lines.\n -@end example - -@item output @var{expression} -@kindex output -Print the value of @var{expression} and nothing but that value: no -newlines, no @samp{$@var{nn} = }. The value is not entered in the -value history either. @xref{Expressions, ,Expressions}, for more information on -expressions. - -@item output/@var{fmt} @var{expression} -Print the value of @var{expression} in format @var{fmt}. You can use -the same formats as for @code{print}. @xref{Output Formats,,Output -formats}, for more information. - -@item printf @var{string}, @var{expressions}@dots{} -@kindex printf -Print the values of the @var{expressions} under the control of -@var{string}. The @var{expressions} are separated by commas and may be -either numbers or pointers. Their values are printed as specified by -@var{string}, exactly as if your program were to execute the C -subroutine - -@example -printf (@var{string}, @var{expressions}@dots{}); -@end example - -For example, you can print two values in hex like this: - -@smallexample -printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo -@end smallexample - -The only backslash-escape sequences that you can use in the format -string are the simple ones that consist of backslash followed by a -letter. -@end table - -@ifclear DOSHOST -@node Emacs -@chapter Using @value{GDBN} under GNU Emacs - -@cindex emacs -A special interface allows you to use GNU Emacs to view (and -edit) the source files for the program you are debugging with -@value{GDBN}. - -To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the -executable file you want to debug as an argument. This command starts -@value{GDBN} as a subprocess of Emacs, with input and output through a newly -created Emacs buffer. - -Using @value{GDBN} under Emacs is just like using @value{GDBN} normally except for two -things: - -@itemize @bullet -@item -All ``terminal'' input and output goes through the Emacs buffer. -@end itemize - -This applies both to @value{GDBN} commands and their output, and to the input -and output done by the program you are debugging. - -This is useful because it means that you can copy the text of previous -commands and input them again; you can even use parts of the output -in this way. - -All the facilities of Emacs' Shell mode are available for interacting -with your program. In particular, you can send signals the usual -way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a -stop. - -@itemize @bullet -@item -@value{GDBN} displays source code through Emacs. -@end itemize - -Each time @value{GDBN} displays a stack frame, Emacs automatically finds the -source file for that frame and puts an arrow (@samp{=>}) at the -left margin of the current line. Emacs uses a separate buffer for -source display, and splits the screen to show both your @value{GDBN} session -and the source. - -Explicit @value{GDBN} @code{list} or search commands still produce output as -usual, but you probably have no reason to use them from Emacs. - -@quotation -@emph{Warning:} If the directory where your program resides is not your -current directory, it can be easy to confuse Emacs about the location of -the source files, in which case the auxiliary display buffer does not -appear to show your source. @value{GDBN} can find programs by searching your -environment's @code{PATH} variable, so the @value{GDBN} input and output -session proceeds normally; but Emacs does not get enough information -back from @value{GDBN} to locate the source files in this situation. To -avoid this problem, either start @value{GDBN} mode from the directory where -your program resides, or specify an absolute file name when prompted for the -@kbd{M-x gdb} argument. - -A similar confusion can result if you use the @value{GDBN} @code{file} command to -switch to debugging a program in some other location, from an existing -@value{GDBN} buffer in Emacs. -@end quotation - -By default, @kbd{M-x gdb} calls the program called @file{gdb}. If -you need to call @value{GDBN} by a different name (for example, if you keep -several configurations around, with different names) you can set the -Emacs variable @code{gdb-command-name}; for example, - -@example -(setq gdb-command-name "mygdb") -@end example - -@noindent -(preceded by @kbd{ESC ESC}, or typed in the @code{*scratch*} buffer, or -in your @file{.emacs} file) makes Emacs call the program named -``@code{mygdb}'' instead. - -In the @value{GDBN} I/O buffer, you can use these special Emacs commands in -addition to the standard Shell mode commands: - -@table @kbd -@item C-h m -Describe the features of Emacs' @value{GDBN} Mode. - -@item M-s -Execute to another source line, like the @value{GDBN} @code{step} command; also -update the display window to show the current file and location. - -@item M-n -Execute to next source line in this function, skipping all function -calls, like the @value{GDBN} @code{next} command. Then update the display window -to show the current file and location. - -@item M-i -Execute one instruction, like the @value{GDBN} @code{stepi} command; update -display window accordingly. - -@item M-x gdb-nexti -Execute to next instruction, using the @value{GDBN} @code{nexti} command; update -display window accordingly. - -@item C-c C-f -Execute until exit from the selected stack frame, like the @value{GDBN} -@code{finish} command. - -@item M-c -Continue execution of your program, like the @value{GDBN} @code{continue} -command. - -@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}. - -@item M-u -Go up the number of frames indicated by the numeric argument -(@pxref{Arguments, , Numeric Arguments, emacs, The GNU Emacs Manual}), -like the @value{GDBN} @code{up} command. - -@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}. - -@item M-d -Go down the number of frames indicated by the numeric argument, like the -@value{GDBN} @code{down} command. - -@emph{Warning:} In Emacs v19, this command is @kbd{C-c C-d}. - -@item C-x & -Read the number where the cursor is positioned, and insert it at the end -of the @value{GDBN} I/O buffer. For example, if you wish to disassemble code -around an address that was displayed earlier, type @kbd{disassemble}; -then move the cursor to the address display, and pick up the -argument for @code{disassemble} by typing @kbd{C-x &}. - -You can customize this further by defining elements of the list -@code{gdb-print-command}; once it is defined, you can format or -otherwise process numbers picked up by @kbd{C-x &} before they are -inserted. A numeric argument to @kbd{C-x &} indicates that you -wish special formatting, and also acts as an index to pick an element of the -list. If the list element is a string, the number to be inserted is -formatted using the Emacs function @code{format}; otherwise the number -is passed as an argument to the corresponding list element. -@end table - -In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break}) -tells @value{GDBN} to set a breakpoint on the source line point is on. - -If you accidentally delete the source-display buffer, an easy way to get -it back is to type the command @code{f} in the @value{GDBN} buffer, to -request a frame display; when you run under Emacs, this recreates -the source buffer if necessary to show you the context of the current -frame. - -The source files displayed in Emacs are in ordinary Emacs buffers -which are visiting the source files in the usual way. You can edit -the files with these buffers if you wish; but keep in mind that @value{GDBN} -communicates with Emacs in terms of line numbers. If you add or -delete lines from the text, the line numbers that @value{GDBN} knows cease -to correspond properly with the code. - -@c The following dropped because Epoch is nonstandard. Reactivate -@c if/when v19 does something similar. ---pesch@cygnus.com 19dec1990 -@ignore -@kindex emacs epoch environment -@kindex epoch -@kindex inspect - -Version 18 of Emacs has a built-in window system called the @code{epoch} -environment. Users of this environment can use a new command, -@code{inspect} which performs identically to @code{print} except that -each value is printed in its own window. -@end ignore -@end ifclear - -@ifset LUCID -@node Energize -@chapter Using @value{GDBN} with Energize - -@cindex Energize -The Energize Programming System is an integrated development environment -that includes a point-and-click interface to many programming tools. -When you use @value{GDBN} in this environment, you can use the standard -Energize graphical interface to drive @value{GDBN}; you can also, if you -choose, type @value{GDBN} commands as usual in a debugging window. Even if -you use the graphical interface, the debugging window (which uses Emacs, -and resembles the standard Emacs interface to @value{GDBN}) displays the -equivalent commands, so that the history of your debugging session is -properly reflected. - -When Energize starts up a @value{GDBN} session, it uses one of the -command-line options @samp{-energize} or @samp{-cadillac} (``cadillac'' -is the name of the communications protocol used by the Energize system). -This option makes @value{GDBN} run as one of the tools in the Energize Tool -Set: it sends all output to the Energize kernel, and accept input from -it as well. - -See the user manual for the Energize Programming System for -information on how to use the Energize graphical interface and the other -development tools that Energize integrates with @value{GDBN}. - -@end ifset - -@node GDB Bugs -@chapter Reporting Bugs in @value{GDBN} -@cindex bugs in @value{GDBN} -@cindex reporting bugs in @value{GDBN} - -Your bug reports play an essential role in making @value{GDBN} reliable. - -Reporting a bug may help you by bringing a solution to your problem, or it -may not. But in any case the principal function of a bug report is to help -the entire community by making the next version of @value{GDBN} work better. Bug -reports are your contribution to the maintenance of @value{GDBN}. - -In order for a bug report to serve its purpose, you must include the -information that enables us to fix the bug. - -@menu -* Bug Criteria:: Have you found a bug? -* Bug Reporting:: How to report bugs -@end menu - -@node Bug Criteria -@section Have you found a bug? -@cindex bug criteria - -If you are not sure whether you have found a bug, here are some guidelines: - -@itemize @bullet -@item -@cindex fatal signal -@cindex debugger crash -@cindex crash of debugger -If the debugger gets a fatal signal, for any input whatever, that is a -@value{GDBN} bug. Reliable debuggers never crash. - -@item -@cindex error on valid input -If @value{GDBN} produces an error message for valid input, that is a bug. - -@item -@cindex invalid input -If @value{GDBN} does not produce an error message for invalid input, -that is a bug. However, you should note that your idea of -``invalid input'' might be our idea of ``an extension'' or ``support -for traditional practice''. - -@item -If you are an experienced user of debugging tools, your suggestions -for improvement of @value{GDBN} are welcome in any case. -@end itemize - -@node Bug Reporting -@section How to report bugs -@cindex bug reports -@cindex @value{GDBN} bugs, reporting - -A number of companies and individuals offer support for GNU products. -If you obtained @value{GDBN} from a support organization, we recommend you -contact that organization first. - -You can find contact information for many support companies and -individuals in the file @file{etc/SERVICE} in the GNU Emacs -distribution. - -In any event, we also recommend that you send bug reports for @value{GDBN} to one -of these addresses: - -@example -bug-gdb@@prep.ai.mit.edu -@{ucbvax|mit-eddie|uunet@}!prep.ai.mit.edu!bug-gdb -@end example - -@strong{Do not send bug reports to @samp{info-gdb}, or to -@samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do not want to -receive bug reports. Those that do, have arranged to receive @samp{bug-gdb}. - -The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which -serves as a repeater. The mailing list and the newsgroup carry exactly -the same messages. Often people think of posting bug reports to the -newsgroup instead of mailing them. This appears to work, but it has one -problem which can be crucial: a newsgroup posting often lacks a mail -path back to the sender. Thus, if we need to ask for more information, -we may be unable to reach you. For this reason, it is better to send -bug reports to the mailing list. - -As a last resort, send bug reports on paper to: - -@example -GNU Debugger Bugs -Free Software Foundation -545 Tech Square -Cambridge, MA 02139 -@end example - -The fundamental principle of reporting bugs usefully is this: -@strong{report all the facts}. If you are not sure whether to state a -fact or leave it out, state it! - -Often people omit facts because they think they know what causes the -problem and assume that some details do not matter. Thus, you might -assume that the name of the variable you use in an example does not matter. -Well, probably it does not, but one cannot be sure. Perhaps the bug is a -stray memory reference which happens to fetch from the location where that -name is stored in memory; perhaps, if the name were different, the contents -of that location would fool the debugger into doing the right thing despite -the bug. Play it safe and give a specific, complete example. That is the -easiest thing for you to do, and the most helpful. - -Keep in mind that the purpose of a bug report is to enable us to fix -the bug if it is new to us. It is not as important as what happens if -the bug is already known. Therefore, always write your bug reports on -the assumption that the bug has not been reported previously. - -Sometimes people give a few sketchy facts and ask, ``Does this ring a -bell?'' Those bug reports are useless, and we urge everyone to -@emph{refuse to respond to them} except to chide the sender to report -bugs properly. - -To enable us to fix the bug, you should include all these things: - -@itemize @bullet -@item -The version of @value{GDBN}. @value{GDBN} announces it if you start with no -arguments; you can also print it at any time using @code{show version}. - -Without this, we will not know whether there is any point in looking for -the bug in the current version of @value{GDBN}. - -@item -The type of machine you are using, and the operating system name and -version number. - -@item -What compiler (and its version) was used to compile @value{GDBN}---e.g. -``@value{GCC}--2.0''. - -@item -What compiler (and its version) was used to compile the program you -are debugging---e.g. ``@value{GCC}--2.0''. - -@item -The command arguments you gave the compiler to compile your example and -observe the bug. For example, did you use @samp{-O}? To guarantee -you will not omit something important, list them all. A copy of the -Makefile (or the output from make) is sufficient. - -If we were to try to guess the arguments, we would probably guess wrong -and then we might not encounter the bug. - -@item -A complete input script, and all necessary source files, that will -reproduce the bug. - -@item -A description of what behavior you observe that you believe is -incorrect. For example, ``It gets a fatal signal.'' - -Of course, if the bug is that @value{GDBN} gets a fatal signal, then we will -certainly notice it. But if the bug is incorrect output, we might not -notice unless it is glaringly wrong. We are human, after all. You -might as well not give us a chance to make a mistake. - -Even if the problem you experience is a fatal signal, you should still -say so explicitly. Suppose something strange is going on, such as, -your copy of @value{GDBN} is out of synch, or you have encountered a -bug in the C library on your system. (This has happened!) Your copy -might crash and ours would not. If you told us to expect a crash, -then when ours fails to crash, we would know that the bug was not -happening for us. If you had not told us to expect a crash, then we -would not be able to draw any conclusion from our observations. - -@item -If you wish to suggest changes to the @value{GDBN} source, send us context -diffs. If you even discuss something in the @value{GDBN} source, refer to -it by context, not by line number. - -The line numbers in our development sources will not match those in your -sources. Your line numbers would convey no useful information to us. -@end itemize - -Here are some things that are not necessary: - -@itemize @bullet -@item -A description of the envelope of the bug. - -Often people who encounter a bug spend a lot of time investigating -which changes to the input file will make the bug go away and which -changes will not affect it. - -This is often time consuming and not very useful, because the way we -will find the bug is by running a single example under the debugger -with breakpoints, not by pure deduction from a series of examples. -We recommend that you save your time for something else. - -Of course, if you can find a simpler example to report @emph{instead} -of the original one, that is a convenience for us. Errors in the -output will be easier to spot, running under the debugger will take -less time, and so on. - -However, simplification is not vital; if you do not want to do this, -report the bug anyway and send us the entire test case you used. - -@item -A patch for the bug. - -A patch for the bug does help us if it is a good one. But do not omit -the necessary information, such as the test case, on the assumption that -a patch is all we need. We might see problems with your patch and decide -to fix the problem another way, or we might not understand it at all. - -Sometimes with a program as complicated as @value{GDBN} it is very hard to -construct an example that will make the program follow a certain path -through the code. If you do not send us the example, we will not be able -to construct one, so we will not be able to verify that the bug is fixed. - -And if we cannot understand what bug you are trying to fix, or why your -patch should be an improvement, we will not install it. A test case will -help us to understand. - -@item -A guess about what the bug is or what it depends on. - -Such guesses are usually wrong. Even we cannot guess right about such -things without first using the debugger to find the facts. -@end itemize - -@c The readline documentation is distributed with the readline code -@c and consists of the two following files: -@c rluser.texinfo -@c inc-hist.texi -@c Use -I with makeinfo to point to the appropriate directory, -@c environment var TEXINPUTS with TeX. -@include rluser.texinfo -@include inc-hist.texi - -@ifset NOVEL -@node Renamed Commands -@appendix Renamed Commands - -The following commands were renamed in GDB 4, in order to make the -command set as a whole more consistent and easier to use and remember: - -@kindex add-syms -@kindex delete environment -@kindex info copying -@kindex info convenience -@kindex info directories -@kindex info editing -@kindex info history -@kindex info targets -@kindex info values -@kindex info version -@kindex info warranty -@kindex set addressprint -@kindex set arrayprint -@kindex set prettyprint -@kindex set screen-height -@kindex set screen-width -@kindex set unionprint -@kindex set vtblprint -@kindex set demangle -@kindex set asm-demangle -@kindex set sevenbit-strings -@kindex set array-max -@kindex set caution -@kindex set history write -@kindex show addressprint -@kindex show arrayprint -@kindex show prettyprint -@kindex show screen-height -@kindex show screen-width -@kindex show unionprint -@kindex show vtblprint -@kindex show demangle -@kindex show asm-demangle -@kindex show sevenbit-strings -@kindex show array-max -@kindex show caution -@kindex show history write -@kindex unset - -@c TEXI2ROFF-KILL -@ifinfo -@c END TEXI2ROFF-KILL -@example -OLD COMMAND NEW COMMAND -@c TEXI2ROFF-KILL ---------------- ------------------------------- -@c END TEXI2ROFF-KILL -add-syms add-symbol-file -delete environment unset environment -info convenience show convenience -info copying show copying -info directories show directories -info editing show commands -info history show values -info targets help target -info values show values -info version show version -info warranty show warranty -set/show addressprint set/show print address -set/show array-max set/show print elements -set/show arrayprint set/show print array -set/show asm-demangle set/show print asm-demangle -set/show caution set/show confirm -set/show demangle set/show print demangle -set/show history write set/show history save -set/show prettyprint set/show print pretty -set/show screen-height set/show height -set/show screen-width set/show width -set/show sevenbit-strings set/show print sevenbit-strings -set/show unionprint set/show print union -set/show vtblprint set/show print vtbl - -unset [No longer an alias for delete] -@end example -@c TEXI2ROFF-KILL -@end ifinfo - -@tex -\vskip \parskip\vskip \baselineskip -\halign{\tt #\hfil &\qquad#&\tt #\hfil\cr -{\bf Old Command} &&{\bf New Command}\cr -add-syms &&add-symbol-file\cr -delete environment &&unset environment\cr -info convenience &&show convenience\cr -info copying &&show copying\cr -info directories &&show directories \cr -info editing &&show commands\cr -info history &&show values\cr -info targets &&help target\cr -info values &&show values\cr -info version &&show version\cr -info warranty &&show warranty\cr -set{\rm / }show addressprint &&set{\rm / }show print address\cr -set{\rm / }show array-max &&set{\rm / }show print elements\cr -set{\rm / }show arrayprint &&set{\rm / }show print array\cr -set{\rm / }show asm-demangle &&set{\rm / }show print asm-demangle\cr -set{\rm / }show caution &&set{\rm / }show confirm\cr -set{\rm / }show demangle &&set{\rm / }show print demangle\cr -set{\rm / }show history write &&set{\rm / }show history save\cr -set{\rm / }show prettyprint &&set{\rm / }show print pretty\cr -set{\rm / }show screen-height &&set{\rm / }show height\cr -set{\rm / }show screen-width &&set{\rm / }show width\cr -set{\rm / }show sevenbit-strings &&set{\rm / }show print sevenbit-strings\cr -set{\rm / }show unionprint &&set{\rm / }show print union\cr -set{\rm / }show vtblprint &&set{\rm / }show print vtbl\cr -\cr -unset &&\rm(No longer an alias for delete)\cr -} -@end tex -@c END TEXI2ROFF-KILL -@end ifset - -@ifclear PRECONFIGURED -@node Formatting Documentation -@appendix Formatting Documentation - -@cindex GDB reference card -@cindex reference card -The GDB 4 release includes an already-formatted reference card, ready -for printing with PostScript or Ghostscript, in the @file{gdb} -subdirectory of the main source directory@footnote{In -@file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN} -release.}. If you can use PostScript or Ghostscript with your printer, -you can print the reference card immediately with @file{refcard.ps}. - -The release also includes the source for the reference card. You -can format it, using @TeX{}, by typing: - -@example -make refcard.dvi -@end example - -The GDB reference card is designed to print in landscape mode on US -``letter'' size paper; that is, on a sheet 11 inches wide by 8.5 inches -high. You will need to specify this form of printing as an option to -your @sc{dvi} output program. - -@cindex documentation - -All the documentation for GDB comes as part of the machine-readable -distribution. The documentation is written in Texinfo format, which is -a documentation system that uses a single source file to produce both -on-line information and a printed manual. You can use one of the Info -formatting commands to create the on-line version of the documentation -and @TeX{} (or @code{texi2roff}) to typeset the printed version. - -GDB includes an already formatted copy of the on-line Info version of -this manual in the @file{gdb} subdirectory. The main Info file is -@file{gdb-@var{version-number}/gdb/gdb.info}, and it refers to -subordinate files matching @samp{gdb.info*} in the same directory. If -necessary, you can print out these files, or read them with any editor; -but they are easier to read using the @code{info} subsystem in GNU Emacs -or the standalone @code{info} program, available as part of the GNU -Texinfo distribution. - -If you want to format these Info files yourself, you need one of the -Info formatting programs, such as @code{texinfo-format-buffer} or -@code{makeinfo}. - -If you have @code{makeinfo} installed, and are in the top level GDB -source directory (@file{gdb-@value{GDBVN}}, in the case of version @value{GDBVN}), you can -make the Info file by typing: - -@example -cd gdb -make gdb.info -@end example - -If you want to typeset and print copies of this manual, you need @TeX{}, -a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the -Texinfo definitions file. - -@TeX{} is a typesetting program; it does not print files directly, but -produces output files called @sc{dvi} files. To print a typeset -document, you need a program to print @sc{dvi} files. If your system -has @TeX{} installed, chances are it has such a program. The precise -command to use depends on your system; @kbd{lpr -d} is common; another -(for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may -require a file name without any extension or a @samp{.dvi} extension. - -@TeX{} also requires a macro definitions file called -@file{texinfo.tex}. This file tells @TeX{} how to typeset a document -written in Texinfo format. On its own, @TeX{} cannot read, much less -typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB -and is located in the @file{gdb-@var{version-number}/texinfo} -directory. - -If you have @TeX{} and a @sc{dvi} printer program installed, you can -typeset and print this manual. First switch to the the @file{gdb} -subdirectory of the main source directory (for example, to -@file{gdb-@value{GDBVN}/gdb}) and then type: - -@example -make gdb.dvi -@end example - -@node Installing GDB -@appendix Installing GDB -@cindex configuring GDB -@cindex installation - -GDB comes with a @code{configure} script that automates the process -of preparing GDB for installation; you can then use @code{make} to -build the @code{gdb} program. -@iftex -@c irrelevant in info file; it's as current as the code it lives with. -@footnote{If you have a more recent version of GDB than @value{GDBVN}, -look at the @file{README} file in the sources; we may have improved the -installation procedures since publishing this manual.} -@end iftex - -The GDB distribution includes all the source code you need for GDB in -a single directory, whose name is usually composed by appending the -version number to @samp{gdb}. - -For example, the GDB version @value{GDBVN} distribution is in the -@file{gdb-@value{GDBVN}} directory. That directory contains: - -@table @code -@item gdb-@value{GDBVN}/configure @r{(and supporting files)} -script for configuring GDB and all its supporting libraries. - -@item gdb-@value{GDBVN}/gdb -the source specific to GDB itself - -@item gdb-@value{GDBVN}/bfd -source for the Binary File Descriptor library - -@item gdb-@value{GDBVN}/include -GNU include files - -@item gdb-@value{GDBVN}/libiberty -source for the @samp{-liberty} free software library - -@item gdb-@value{GDBVN}/opcodes -source for the library of opcode tables and disassemblers - -@item gdb-@value{GDBVN}/readline -source for the GNU command-line interface - -@item gdb-@value{GDBVN}/glob -source for the GNU filename pattern-matching subroutine - -@item gdb-@value{GDBVN}/mmalloc -source for the GNU memory-mapped malloc package -@end table - -The simplest way to configure and build GDB is to run @code{configure} -from the @file{gdb-@var{version-number}} source directory, which in -this example is the @file{gdb-@value{GDBVN}} directory. - -First switch to the @file{gdb-@var{version-number}} source directory -if you are not already in it; then run @code{configure}. Pass the -identifier for the platform on which GDB will run as an -argument. - -For example: - -@example -cd gdb-@value{GDBVN} -./configure @var{host} -make -@end example - -@noindent -where @var{host} is an identifier such as @samp{sun4} or -@samp{decstation}, that identifies the platform where GDB will run. -(You can often leave off @var{host}; @code{configure} tries to guess the -correct value by examining your system.) - -Running @samp{configure @var{host}} and then running @code{make} builds the -@file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty} -libraries, then @code{gdb} itself. The configured source files, and the -binaries, are left in the corresponding source directories. - -@code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your -system does not recognize this automatically when you run a different -shell, you may need to run @code{sh} on it explicitly: - -@example -sh configure @var{host} -@end example - -If you run @code{configure} from a directory that contains source -directories for multiple libraries or programs, such as the -@file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, @code{configure} -creates configuration files for every directory level underneath (unless -you tell it not to, with the @samp{--norecursion} option). - -You can run the @code{configure} script from any of the -subordinate directories in the GDB distribution if you only want to -configure that subdirectory, but be sure to specify a path to it. - -For example, with version @value{GDBVN}, type the following to configure only -the @code{bfd} subdirectory: - -@example -@group -cd gdb-@value{GDBVN}/bfd -../configure @var{host} -@end group -@end example - -You can install @code{@value{GDBP}} anywhere; it has no hardwired paths. -However, you should make sure that the shell on your path (named by -the @samp{SHELL} environment variable) is publicly readable. Remember -that GDB uses the shell to start your program---some systems refuse to -let GDB debug child processes whose programs are not readable. - -@menu -* Separate Objdir:: Compiling GDB in another directory -* Config Names:: Specifying names for hosts and targets -* configure Options:: Summary of options for configure -@end menu - -@node Separate Objdir -@section Compiling GDB in another directory - -If you want to run GDB versions for several host or target machines, -you need a different @code{gdb} compiled for each combination of -host and target. @code{configure} is designed to make this easy by -allowing you to generate each configuration in a separate subdirectory, -rather than in the source directory. If your @code{make} program -handles the @samp{VPATH} feature (GNU @code{make} does), running -@code{make} in each of these directories builds the @code{gdb} -program specified there. - -To build @code{gdb} in a separate directory, run @code{configure} -with the @samp{--srcdir} option to specify where to find the source. -(You also need to specify a path to find @code{configure} -itself from your working directory. If the path to @code{configure} -would be the same as the argument to @samp{--srcdir}, you can leave out -the @samp{--srcdir} option; it is assumed.) - -For example, with version @value{GDBVN}, you can build GDB in a separate -directory for a Sun 4 like this: - -@example -@group -cd gdb-@value{GDBVN} -mkdir ../gdb-sun4 -cd ../gdb-sun4 -../gdb-@value{GDBVN}/configure sun4 -make -@end group -@end example - -When @code{configure} builds a configuration using a remote source -directory, it creates a tree for the binaries with the same structure -(and using the same names) as the tree under the source directory. In -the example, you'd find the Sun 4 library @file{libiberty.a} in the -directory @file{gdb-sun4/libiberty}, and GDB itself in -@file{gdb-sun4/gdb}. - -One popular reason to build several GDB configurations in separate -directories is to configure GDB for cross-compiling (where GDB -runs on one machine---the host---while debugging programs that run on -another machine---the target). You specify a cross-debugging target by -giving the @samp{--target=@var{target}} option to @code{configure}. - -When you run @code{make} to build a program or library, you must run -it in a configured directory---whatever directory you were in when you -called @code{configure} (or one of its subdirectories). - -The @code{Makefile} that @code{configure} generates in each source -directory also runs recursively. If you type @code{make} in a source -directory such as @file{gdb-@value{GDBVN}} (or in a separate configured -directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you -will build all the required libraries, and then build GDB. - -When you have multiple hosts or targets configured in separate -directories, you can run @code{make} on them in parallel (for example, -if they are NFS-mounted on each of the hosts); they will not interfere -with each other. - -@node Config Names -@section Specifying names for hosts and targets - -The specifications used for hosts and targets in the @code{configure} -script are based on a three-part naming scheme, but some short predefined -aliases are also supported. The full naming scheme encodes three pieces -of information in the following pattern: - -@example -@var{architecture}-@var{vendor}-@var{os} -@end example - -For example, you can use the alias @code{sun4} as a @var{host} argument, -or as the value for @var{target} in a @code{--target=@var{target}} -option. The equivalent full name is @samp{sparc-sun-sunos4}. - -The @code{configure} script accompanying GDB does not provide -any query facility to list all supported host and target names or -aliases. @code{configure} calls the Bourne shell script -@code{config.sub} to map abbreviations to full names; you can read the -script, if you wish, or you can use it to test your guesses on -abbreviations---for example: - -@smallexample -% sh config.sub sun4 -sparc-sun-sunos4.1.1 -% sh config.sub sun3 -m68k-sun-sunos4.1.1 -% sh config.sub decstation -mips-dec-ultrix4.2 -% sh config.sub hp300bsd -m68k-hp-bsd -% sh config.sub i386v -i386-unknown-sysv -% sh config.sub i786v -Invalid configuration `i786v': machine `i786v' not recognized -@end smallexample - -@noindent -@code{config.sub} is also distributed in the GDB source -directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}). - -@node configure Options -@section @code{configure} options - -Here is a summary of the @code{configure} options and arguments that -are most often useful for building @value{GDBN}. @code{configure} also has -several other options not listed here. @inforef{What Configure -Does,,configure.info}, for a full explanation of @code{configure}. -@c FIXME: Would this be more, or less, useful as an xref (ref to printed -@c manual in the printed manual, ref to info file only from the info file)? - -@example -configure @r{[}--help@r{]} - @r{[}--prefix=@var{dir}@r{]} - @r{[}--srcdir=@var{dirname}@r{]} - @r{[}--norecursion@r{]} @r{[}--rm@r{]} - @r{[}--target=@var{target}@r{]} @var{host} -@end example - -@noindent -You may introduce options with a single @samp{-} rather than -@samp{--} if you prefer; but you may abbreviate option names if you use -@samp{--}. - -@table @code -@item --help -Display a quick summary of how to invoke @code{configure}. - -@item -prefix=@var{dir} -Configure the source to install programs and files under directory -@file{@var{dir}}. - -@c avoid splitting the warning from the explanation: -@need 2000 -@item --srcdir=@var{dirname} -@strong{Warning: using this option requires GNU @code{make}, or another -@code{make} that implements the @code{VPATH} feature.}@* -Use this option to make configurations in directories separate from the -GDB source directories. Among other things, you can use this to -build (or maintain) several configurations simultaneously, in separate -directories. @code{configure} writes configuration specific files in -the current directory, but arranges for them to use the source in the -directory @var{dirname}. @code{configure} creates directories under -the working directory in parallel to the source directories below -@var{dirname}. - -@item --norecursion -Configure only the directory level where @code{configure} is executed; do not -propagate configuration to subdirectories. - -@item --rm -@emph{Remove} files otherwise built during configuration. - -@c This does not work (yet if ever). FIXME. -@c @item --parse=@var{lang} @dots{} -@c Configure the GDB expression parser to parse the listed languages. -@c @samp{all} configures GDB for all supported languages. To get a -@c list of all supported languages, omit the argument. Without this -@c option, GDB is configured to parse all supported languages. - -@item --target=@var{target} -Configure GDB for cross-debugging programs running on the specified -@var{target}. Without this option, GDB is configured to debug -programs that run on the same machine (@var{host}) as GDB itself. - -There is no convenient way to generate a list of all available targets. - -@item @var{host} @dots{} -Configure GDB to run on the specified @var{host}. - -There is no convenient way to generate a list of all available hosts. -@end table - -@noindent -@code{configure} accepts other options, for compatibility with -configuring other GNU tools recursively; but these are the only -options that affect GDB or its supporting libraries. -@end ifclear - -@node Index -@unnumbered Index - -@printindex cp - -@tex -% I think something like @colophon should be in texinfo. In the -% meantime: -\long\def\colophon{\hbox to0pt{}\vfill -\centerline{The body of this manual is set in} -\centerline{\fontname\tenrm,} -\centerline{with headings in {\bf\fontname\tenbf}} -\centerline{and examples in {\tt\fontname\tentt}.} -\centerline{{\it\fontname\tenit\/},} -\centerline{{\bf\fontname\tenbf}, and} -\centerline{{\sl\fontname\tensl\/}} -\centerline{are used for emphasis.}\vfill} -\page\colophon -% Blame: pesch@cygnus.com, 1991. -@end tex - -@contents -@bye diff --git a/gnu/usr.bin/gdb/doc/gdbint.texinfo b/gnu/usr.bin/gdb/doc/gdbint.texinfo deleted file mode 100644 index bd96420..0000000 --- a/gnu/usr.bin/gdb/doc/gdbint.texinfo +++ /dev/null @@ -1,2669 +0,0 @@ -\input texinfo -@setfilename gdbint.info -@c $FreeBSD$ - -@ifinfo -@format -START-INFO-DIR-ENTRY -* Gdb-Internals: (gdbint). The GNU debugger's internals. -END-INFO-DIR-ENTRY -@end format -@end ifinfo - -@ifinfo -This file documents the internals of the GNU debugger GDB. - -Copyright 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc. -Contributed by Cygnus Support. Written by John Gilmore. - -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -@ignore -Permission is granted to process this file through Tex and print the -results, provided the printed document carries copying permission -notice identical to this one except for the removal of this paragraph -(this paragraph not being relevant to the printed manual). - -@end ignore -Permission is granted to copy or distribute modified versions of this -manual under the terms of the GPL (for which purpose this text may be -regarded as a program in the language TeX). -@end ifinfo - -@setchapternewpage off -@settitle GDB Internals -@titlepage -@title{Working in GDB} -@subtitle{A guide to the internals of the GNU debugger} -@author John Gilmore -@author Cygnus Support -@page -@tex -\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$ -\xdef\manvers{\$Revision: 1.2 $} % For use in headers, footers too -{\parskip=0pt -\hfill Cygnus Support\par -\hfill \manvers\par -\hfill \TeX{}info \texinfoversion\par -} -@end tex - -@vskip 0pt plus 1filll -Copyright @copyright{} 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc. - -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -@end titlepage - -@node Top -@c Perhaps this should be the title of the document (but only for info, -@c not for TeX). Existing GNU manuals seem inconsistent on this point. -@top Scope of this Document - -This document documents the internals of the GNU debugger, GDB. It is -intended to document aspects of GDB which apply across many different -parts of GDB (for example, @pxref{Coding Style}), or which are global -aspects of design (for example, what are the major modules and which -files document them in detail?). Information which pertains to specific -data structures, functions, variables, etc., should be put in comments -in the source code, not here. It is more likely to get noticed and kept -up to date there. Some of the information in this document should -probably be moved into comments. - -@menu -* README:: The README File -* Getting Started:: Getting started working on GDB -* Debugging GDB:: Debugging GDB with itself -* New Architectures:: Defining a New Host or Target Architecture -* Config:: Adding a New Configuration -* Host:: Adding a New Host -* Native:: Adding a New Native Configuration -* Target:: Adding a New Target -* Languages:: Defining New Source Languages -* Releases:: Configuring GDB for Release -* Partial Symbol Tables:: How GDB reads symbols quickly at startup -* Types:: How GDB keeps track of types -* BFD support for GDB:: How BFD and GDB interface -* Symbol Reading:: Defining New Symbol Readers -* Cleanups:: Cleanups -* Wrapping:: Wrapping Output Lines -* Frames:: Keeping track of function calls -* Remote Stubs:: Code that runs in targets and talks to GDB -* Longjmp Support:: Stepping through longjmp's in the target -* Coding Style:: Strunk and White for GDB maintainers -* Clean Design:: Frank Lloyd Wright for GDB maintainers -* Submitting Patches:: How to get your changes into GDB releases -* Host Conditionals:: What features exist in the host -* Target Conditionals:: What features exist in the target -* Native Conditionals:: Conditionals for when host and target are same -* Obsolete Conditionals:: Conditionals that don't exist any more -* XCOFF:: The Object file format used on IBM's RS/6000 -@end menu - -@node README -@chapter The @file{README} File - -Check the @file{README} file, it often has useful information that does not -appear anywhere else in the directory. - -@node Getting Started -@chapter Getting Started Working on GDB - -GDB is a large and complicated program, and if you first starting to -work on it, it can be hard to know where to start. Fortunately, if you -know how to go about it, there are ways to figure out what is going on: - -@itemize @bullet -@item -This manual, the GDB Internals manual, has information which applies -generally to many parts of GDB. - -@item -Information about particular functions or data structures are located in -comments with those functions or data structures. If you run across a -function or a global variable which does not have a comment correctly -explaining what is does, this can be thought of as a bug in GDB; feel -free to submit a bug report, with a suggested comment if you can figure -out what the comment should say (@pxref{Submitting Patches}). If you -find a comment which is actually wrong, be especially sure to report that. - -Comments explaining the function of macros defined in host, target, or -native dependent files can be in several places. Sometimes they are -repeated every place the macro is defined. Sometimes they are where the -macro is used. Sometimes there is a header file which supplies a -default definition of the macro, and the comment is there. This manual -also has a list of macros (@pxref{Host Conditionals}, @pxref{Target -Conditionals}, @pxref{Native Conditionals}, and @pxref{Obsolete -Conditionals}) with some documentation. - -@item -Start with the header files. Once you some idea of how GDB's internal -symbol tables are stored (see @file{symtab.h}, @file{gdbtypes.h}), you -will find it much easier to understand the code which uses and creates -those symbol tables. - -@item -You may wish to process the information you are getting somehow, to -enhance your understanding of it. Summarize it, translate it to another -language, add some (perhaps trivial or non-useful) feature to GDB, use -the code to predict what a test case would do and write the test case -and verify your prediction, etc. If you are reading code and your eyes -are starting to glaze over, this is a sign you need to use a more active -approach. - -@item -Once you have a part of GDB to start with, you can find more -specifically the part you are looking for by stepping through each -function with the @code{next} command. Do not use @code{step} or you -will quickly get distracted; when the function you are stepping through -calls another function try only to get a big-picture understanding -(perhaps using the comment at the beginning of the function being -called) of what it does. This way you can identify which of the -functions being called by the function you are stepping through is the -one which you are interested in. You may need to examine the data -structures generated at each stage, with reference to the comments in -the header files explaining what the data structures are supposed to -look like. - -Of course, this same technique can be used if you are just reading the -code, rather than actually stepping through it. The same general -principle applies---when the code you are looking at calls something -else, just try to understand generally what the code being called does, -rather than worrying about all its details. - -@item -A good place to start when tracking down some particular area is with a -command which invokes that feature. Suppose you want to know how -single-stepping works. As a GDB user, you know that the @code{step} -command invokes single-stepping. The command is invoked via command -tables (see @file{command.h}); by convention the function which actually -performs the command is formed by taking the name of the command and -adding @samp{_command}, or in the case of an @code{info} subcommand, -@samp{_info}. For example, the @code{step} command invokes the -@code{step_command} function and the @code{info display} command invokes -@code{display_info}. When this convention is not followed, you might -have to use @code{grep} or @kbd{M-x tags-search} in emacs, or run GDB on -itself and set a breakpoint in @code{execute_command}. - -@item -If all of the above fail, it may be appropriate to ask for information -on @code{bug-gdb}. But @emph{never} post a generic question like ``I was -wondering if anyone could give me some tips about understanding -GDB''---if we had some magic secret we would put it in this manual. -Suggestions for improving the manual are always welcome, of course. -@end itemize - -Good luck! - -@node Debugging GDB -@chapter Debugging GDB with itself -If GDB is limping on your machine, this is the preferred way to get it -fully functional. Be warned that in some ancient Unix systems, like -Ultrix 4.2, a program can't be running in one process while it is being -debugged in another. Rather than typing the command @code{@w{./gdb -./gdb}}, which works on Suns and such, you can copy @file{gdb} to -@file{gdb2} and then type @code{@w{./gdb ./gdb2}}. - -When you run GDB in the GDB source directory, it will read a -@file{.gdbinit} file that sets up some simple things to make debugging -gdb easier. The @code{info} command, when executed without a subcommand -in a GDB being debugged by gdb, will pop you back up to the top level -gdb. See @file{.gdbinit} for details. - -If you use emacs, you will probably want to do a @code{make TAGS} after -you configure your distribution; this will put the machine dependent -routines for your local machine where they will be accessed first by -@kbd{M-.} - -Also, make sure that you've either compiled GDB with your local cc, or -have run @code{fixincludes} if you are compiling with gcc. - -@node New Architectures -@chapter Defining a New Host or Target Architecture - -When building support for a new host and/or target, much of the work you -need to do is handled by specifying configuration files; -@pxref{Config,,Adding a New Configuration}. Further work can be -divided into ``host-dependent'' (@pxref{Host,,Adding a New Host}) and -``target-dependent'' (@pxref{Target,,Adding a New Target}). The -following discussion is meant to explain the difference between hosts -and targets. - -@heading What is considered ``host-dependent'' versus ``target-dependent''? - -@dfn{Host} refers to attributes of the system where GDB runs. -@dfn{Target} refers to the system where the program being debugged -executes. In most cases they are the same machine, in which case -a third type of @dfn{Native} attributes come into play. - -Defines and include files needed to build on the host are host support. -Examples are tty support, system defined types, host byte order, host -float format. - -Defines and information needed to handle the target format are target -dependent. Examples are the stack frame format, instruction set, -breakpoint instruction, registers, and how to set up and tear down the stack -to call a function. - -Information that is only needed when the host and target are the same, -is native dependent. One example is Unix child process support; if the -host and target are not the same, doing a fork to start the target -process is a bad idea. The various macros needed for finding the -registers in the @code{upage}, running @code{ptrace}, and such are all in the -native-dependent files. - -Another example of native-dependent code is support for features -that are really part of the target environment, but which require -@code{#include} files that are only available on the host system. -Core file handling and @code{setjmp} handling are two common cases. - -When you want to make GDB work ``native'' on a particular -machine, you have to include all three kinds of information. - -The dependent information in GDB is organized into files by naming -conventions. - -Host-Dependent Files -@table @file -@item config/*/*.mh -Sets Makefile parameters -@item config/*/xm-*.h -Global #include's and #define's and definitions -@item *-xdep.c -Global variables and functions -@end table - -Native-Dependent Files -@table @file -@item config/*/*.mh -Sets Makefile parameters (for @emph{both} host and native) -@item config/*/nm-*.h -#include's and #define's and definitions. This file -is only included by the small number of modules that need it, -so beware of doing feature-test #define's from its macros. -@item *-nat.c -global variables and functions -@end table - -Target-Dependent Files -@table @file -@item config/*/*.mt -Sets Makefile parameters -@item config/*/tm-*.h -Global #include's and #define's and definitions -@item *-tdep.c -Global variables and functions -@end table - -At this writing, most supported hosts have had their host and native -dependencies sorted out properly. There are a few stragglers, which -can be recognized by the absence of NATDEPFILES lines in their -@file{config/*/*.mh}. - -@node Config -@chapter Adding a New Configuration - -Most of the work in making GDB compile on a new machine is in specifying -the configuration of the machine. This is done in a dizzying variety of -header files and configuration scripts, which we hope to make more -sensible soon. Let's say your new host is called an @var{xxx} (e.g. -@samp{sun4}), and its full three-part configuration name is -@code{@var{xarch}-@var{xvend}-@var{xos}} (e.g. @samp{sparc-sun-sunos4}). In -particular: - -In the top level directory, edit @file{config.sub} and add @var{xarch}, -@var{xvend}, and @var{xos} to the lists of supported architectures, -vendors, and operating systems near the bottom of the file. Also, add -@var{xxx} as an alias that maps to -@code{@var{xarch}-@var{xvend}-@var{xos}}. You can test your changes by -running - -@example -./config.sub @var{xxx} -@end example -@noindent -and -@example -./config.sub @code{@var{xarch}-@var{xvend}-@var{xos}} -@end example -@noindent -which should both respond with @code{@var{xarch}-@var{xvend}-@var{xos}} -and no error messages. - -Now, go to the @file{bfd} directory and -create a new file @file{bfd/hosts/h-@var{xxx}.h}. Examine the -other @file{h-*.h} files as templates, and create one that brings in the -right include files for your system, and defines any host-specific -macros needed by BFD, the Binutils, GNU LD, or the Opcodes directories. -(They all share the bfd @file{hosts} directory and the @file{configure.host} -file.) - -Then edit @file{bfd/configure.host}. Add a line to recognize your -@code{@var{xarch}-@var{xvend}-@var{xos}} configuration, and set -@code{my_host} to @var{xxx} when you recognize it. This will cause your -file @file{h-@var{xxx}.h} to be linked to @file{sysdep.h} at configuration -time. When creating the line that recognizes your configuration, -only match the fields that you really need to match; e.g. don't -match the architecture or manufacturer if the OS is sufficient -to distinguish the configuration that your @file{h-@var{xxx}.h} file supports. -Don't match the manufacturer name unless you really need to. -This should make future ports easier. - -Also, if this host requires any changes to the Makefile, create a file -@file{bfd/config/@var{xxx}.mh}, which includes the required lines. - -It's possible that the @file{libiberty} and @file{readline} directories -won't need any changes for your configuration, but if they do, you can -change the @file{configure.in} file there to recognize your system and -map to an @file{mh-@var{xxx}} file. Then add @file{mh-@var{xxx}} -to the @file{config/} subdirectory, to set any makefile variables you -need. The only current options in there are things like @samp{-DSYSV}. -(This @file{mh-@var{xxx}} naming convention differs from elsewhere -in GDB, by historical accident. It should be cleaned up so that all -such files are called @file{@var{xxx}.mh}.) - -Aha! Now to configure GDB itself! Edit -@file{gdb/configure.in} to recognize your system and set @code{gdb_host} -to @var{xxx}, and (unless your desired target is already available) also -set @code{gdb_target} to something appropriate (for instance, -@var{xxx}). To handle new hosts, modify the segment after the comment -@samp{# per-host}; to handle new targets, modify after @samp{# -per-target}. -@c Would it be simpler to just use different per-host and per-target -@c *scripts*, and call them from {configure} ? - -Finally, you'll need to specify and define GDB's host-, native-, and -target-dependent @file{.h} and @file{.c} files used for your -configuration; the next two chapters discuss those. - - -@node Host -@chapter Adding a New Host - -Once you have specified a new configuration for your host -(@pxref{Config,,Adding a New Configuration}), there are three remaining -pieces to making GDB work on a new machine. First, you have to make it -host on the new machine (compile there, handle that machine's terminals -properly, etc). If you will be cross-debugging to some other kind of -system that's already supported, you are done. - -If you want to use GDB to debug programs that run on the new machine, -you have to get it to understand the machine's object files, symbol -files, and interfaces to processes; @pxref{Target,,Adding a New Target} -and @pxref{Native,,Adding a New Native Configuration} - -Several files control GDB's configuration for host systems: - -@table @file -@item gdb/config/@var{arch}/@var{xxx}.mh -Specifies Makefile fragments needed when hosting on machine @var{xxx}. -In particular, this lists the required machine-dependent object files, -by defining @samp{XDEPFILES=@dots{}}. Also -specifies the header file which describes host @var{xxx}, by defining -@code{XM_FILE= xm-@var{xxx}.h}. You can also define @code{CC}, -@code{REGEX} and @code{REGEX1}, @code{SYSV_DEFINE}, @code{XM_CFLAGS}, -@code{XM_ADD_FILES}, @code{XM_CLIBS}, @code{XM_CDEPS}, -etc.; see @file{Makefile.in}. - -@item gdb/config/@var{arch}/xm-@var{xxx}.h -(@file{xm.h} is a link to this file, created by configure). -Contains C macro definitions describing the host system environment, -such as byte order, host C compiler and library, ptrace support, -and core file structure. Crib from existing @file{xm-*.h} files -to create a new one. - -@item gdb/@var{xxx}-xdep.c -Contains any miscellaneous C code required for this machine -as a host. On many machines it doesn't exist at all. If it does -exist, put @file{@var{xxx}-xdep.o} into the @code{XDEPFILES} line -in @file{gdb/config/mh-@var{xxx}}. -@end table - -@subheading Generic Host Support Files - -There are some ``generic'' versions of routines that can be used by -various systems. These can be customized in various ways by macros -defined in your @file{xm-@var{xxx}.h} file. If these routines work for -the @var{xxx} host, you can just include the generic file's name (with -@samp{.o}, not @samp{.c}) in @code{XDEPFILES}. - -Otherwise, if your machine needs custom support routines, you will need -to write routines that perform the same functions as the generic file. -Put them into @code{@var{xxx}-xdep.c}, and put @code{@var{xxx}-xdep.o} -into @code{XDEPFILES}. - -@table @file -@item ser-bsd.c -This contains serial line support for Berkeley-derived Unix systems. - -@item ser-go32.c -This contains serial line support for 32-bit programs running under DOS -using the GO32 execution environment. - -@item ser-termios.c -This contains serial line support for System V-derived Unix systems. -@end table - -Now, you are now ready to try configuring GDB to compile using your system -as its host. From the top level (above @file{bfd}, @file{gdb}, etc), do: - -@example -./configure @var{xxx} --target=vxworks960 -@end example - -This will configure your system to cross-compile for VxWorks on -the Intel 960, which is probably not what you really want, but it's -a test case that works at this stage. (You haven't set up to be -able to debug programs that run @emph{on} @var{xxx} yet.) - -If this succeeds, you can try building it all with: - -@example -make -@end example - -Repeat until the program configures, compiles, links, and runs. -When run, it won't be able to do much (unless you have a VxWorks/960 -board on your network) but you will know that the host support is -pretty well done. - -Good luck! Comments and suggestions about this section are particularly -welcome; send them to @samp{bug-gdb@@prep.ai.mit.edu}. - -@node Native -@chapter Adding a New Native Configuration - -If you are making GDB run native on the @var{xxx} machine, you have -plenty more work to do. Several files control GDB's configuration for -native support: - -@table @file -@item gdb/config/@var{xarch}/@var{xxx}.mh -Specifies Makefile fragments needed when hosting @emph{or native} -on machine @var{xxx}. -In particular, this lists the required native-dependent object files, -by defining @samp{NATDEPFILES=@dots{}}. Also -specifies the header file which describes native support on @var{xxx}, -by defining @samp{NAT_FILE= nm-@var{xxx}.h}. -You can also define @samp{NAT_CFLAGS}, -@samp{NAT_ADD_FILES}, @samp{NAT_CLIBS}, @samp{NAT_CDEPS}, -etc.; see @file{Makefile.in}. - -@item gdb/config/@var{arch}/nm-@var{xxx}.h -(@file{nm.h} is a link to this file, created by configure). -Contains C macro definitions describing the native system environment, -such as child process control and core file support. -Crib from existing @file{nm-*.h} files to create a new one. - -@item gdb/@var{xxx}-nat.c -Contains any miscellaneous C code required for this native support -of this machine. On some machines it doesn't exist at all. -@end table - -@subheading Generic Native Support Files - -There are some ``generic'' versions of routines that can be used by -various systems. These can be customized in various ways by macros -defined in your @file{nm-@var{xxx}.h} file. If these routines work for -the @var{xxx} host, you can just include the generic file's name (with -@samp{.o}, not @samp{.c}) in @code{NATDEPFILES}. - -Otherwise, if your machine needs custom support routines, you will need -to write routines that perform the same functions as the generic file. -Put them into @code{@var{xxx}-nat.c}, and put @code{@var{xxx}-nat.o} -into @code{NATDEPFILES}. - -@table @file - -@item inftarg.c -This contains the @emph{target_ops vector} that supports Unix child -processes on systems which use ptrace and wait to control the child. - -@item procfs.c -This contains the @emph{target_ops vector} that supports Unix child -processes on systems which use /proc to control the child. - -@item fork-child.c -This does the low-level grunge that uses Unix system calls -to do a "fork and exec" to start up a child process. - -@item infptrace.c -This is the low level interface to inferior processes for systems -using the Unix @code{ptrace} call in a vanilla way. - -@item coredep.c::fetch_core_registers() -Support for reading registers out of a core file. This routine calls -@code{register_addr()}, see below. -Now that BFD is used to read core files, virtually all machines should -use @code{coredep.c}, and should just provide @code{fetch_core_registers} in -@code{@var{xxx}-nat.c} (or @code{REGISTER_U_ADDR} in @code{nm-@var{xxx}.h}). - -@item coredep.c::register_addr() -If your @code{nm-@var{xxx}.h} file defines the macro -@code{REGISTER_U_ADDR(addr, blockend, regno)}, it should be defined to -set @code{addr} to the offset within the @samp{user} -struct of GDB register number @code{regno}. @code{blockend} is the -offset within the ``upage'' of @code{u.u_ar0}. -If @code{REGISTER_U_ADDR} is defined, -@file{coredep.c} will define the @code{register_addr()} function and use -the macro in it. If you do not define @code{REGISTER_U_ADDR}, but you -are using the standard @code{fetch_core_registers()}, you will need to -define your own version of @code{register_addr()}, put it into your -@code{@var{xxx}-nat.c} file, and be sure @code{@var{xxx}-nat.o} is in -the @code{NATDEPFILES} list. If you have your own -@code{fetch_core_registers()}, you may not need a separate -@code{register_addr()}. Many custom @code{fetch_core_registers()} -implementations simply locate the registers themselves.@refill -@end table - -When making GDB run native on a new operating system, -to make it possible to debug -core files, you will need to either write specific code for parsing your -OS's core files, or customize @file{bfd/trad-core.c}. First, use -whatever @code{#include} files your machine uses to define the struct of -registers that is accessible (possibly in the u-area) in a core file -(rather than @file{machine/reg.h}), and an include file that defines whatever -header exists on a core file (e.g. the u-area or a @samp{struct core}). Then -modify @code{trad_unix_core_file_p()} to use these values to set up the -section information for the data segment, stack segment, any other -segments in the core file (perhaps shared library contents or control -information), ``registers'' segment, and if there are two discontiguous -sets of registers (e.g. integer and float), the ``reg2'' segment. This -section information basically delimits areas in the core file in a -standard way, which the section-reading routines in BFD know how to seek -around in. - -Then back in GDB, you need a matching routine called -@code{fetch_core_registers()}. If you can use the generic one, it's in -@file{coredep.c}; if not, it's in your @file{@var{xxx}-nat.c} file. -It will be passed a char pointer to the entire ``registers'' segment, -its length, and a zero; or a char pointer to the entire ``regs2'' -segment, its length, and a 2. The routine should suck out the supplied -register values and install them into GDB's ``registers'' array. -(@xref{New Architectures,,Defining a New Host or Target Architecture}, -for more info about this.) - -If your system uses @file{/proc} to control processes, and uses ELF -format core files, then you may be able to use the same routines -for reading the registers out of processes and out of core files. - -@node Target -@chapter Adding a New Target - -For a new target called @var{ttt}, first specify the configuration as -described in @ref{Config,,Adding a New Configuration}. If your new -target is the same as your new host, you've probably already done that. - -A variety of files specify attributes of the GDB target environment: - -@table @file -@item gdb/config/@var{arch}/@var{ttt}.mt -Contains a Makefile fragment specific to this target. -Specifies what object files are needed for target @var{ttt}, by -defining @samp{TDEPFILES=@dots{}}. -Also specifies the header file which describes @var{ttt}, by defining -@samp{TM_FILE= tm-@var{ttt}.h}. You can also define @samp{TM_CFLAGS}, -@samp{TM_CLIBS}, @samp{TM_CDEPS}, -and other Makefile variables here; see @file{Makefile.in}. - -@item gdb/config/@var{arch}/tm-@var{ttt}.h -(@file{tm.h} is a link to this file, created by configure). -Contains macro definitions about the target machine's -registers, stack frame format and instructions. -Crib from existing @file{tm-*.h} files when building a new one. - -@item gdb/@var{ttt}-tdep.c -Contains any miscellaneous code required for this target machine. -On some machines it doesn't exist at all. Sometimes the macros -in @file{tm-@var{ttt}.h} become very complicated, so they are -implemented as functions here instead, and the macro is simply -defined to call the function. - -@item gdb/exec.c -Defines functions for accessing files that are -executable on the target system. These functions open and examine an -exec file, extract data from one, write data to one, print information -about one, etc. Now that executable files are handled with BFD, every -target should be able to use the generic exec.c rather than its -own custom code. - -@item gdb/@var{arch}-pinsn.c -Prints (disassembles) the target machine's instructions. -This file is usually shared with other target machines which use the -same processor, which is why it is @file{@var{arch}-pinsn.c} rather -than @file{@var{ttt}-pinsn.c}. - -@item gdb/@var{arch}-opcode.h -Contains some large initialized -data structures describing the target machine's instructions. -This is a bit strange for a @file{.h} file, but it's OK since -it is only included in one place. @file{@var{arch}-opcode.h} is shared -between the debugger and the assembler, if the GNU assembler has been -ported to the target machine. - -@item gdb/config/@var{arch}/tm-@var{arch}.h -This often exists to describe the basic layout of the target machine's -processor chip (registers, stack, etc). -If used, it is included by @file{tm-@var{xxx}.h}. It can -be shared among many targets that use the same processor. - -@item gdb/@var{arch}-tdep.c -Similarly, there are often common subroutines that are shared by all -target machines that use this particular architecture. -@end table - -When adding support for a new target machine, there are various areas -of support that might need change, or might be OK. - -If you are using an existing object file format (a.out or COFF), -there is probably little to be done. See @file{bfd/doc/bfd.texinfo} -for more information on writing new a.out or COFF versions. - -If you need to add a new object file format, you must first add it to -BFD. This is beyond the scope of this document right now. Basically -you must build a transfer vector (of type @code{bfd_target}), which will -mean writing all the required routines, and add it to the list in -@file{bfd/targets.c}. - -You must then arrange for the BFD code to provide access to the -debugging symbols. Generally GDB will have to call swapping routines -from BFD and a few other BFD internal routines to locate the debugging -information. As much as possible, GDB should not depend on the BFD -internal data structures. - -For some targets (e.g., COFF), there is a special transfer vector used -to call swapping routines, since the external data structures on various -platforms have different sizes and layouts. Specialized routines that -will only ever be implemented by one object file format may be called -directly. This interface should be described in a file -@file{bfd/libxxx.h}, which is included by GDB. - -If you are adding a new operating system for an existing CPU chip, add a -@file{tm-@var{xos}.h} file that describes the operating system -facilities that are unusual (extra symbol table info; the breakpoint -instruction needed; etc). Then write a -@file{tm-@var{xarch}-@var{xos}.h} that just @code{#include}s -@file{tm-@var{xarch}.h} and @file{tm-@var{xos}.h}. (Now that we have -three-part configuration names, this will probably get revised to -separate the @var{xos} configuration from the @var{xarch} -configuration.) - - -@node Languages -@chapter Adding a Source Language to GDB - -To add other languages to GDB's expression parser, follow the following steps: - -@table @emph -@item Create the expression parser. - -This should reside in a file @file{@var{lang}-exp.y}. Routines for building -parsed expressions into a @samp{union exp_element} list are in @file{parse.c}. - -Since we can't depend upon everyone having Bison, and YACC produces -parsers that define a bunch of global names, the following lines -@emph{must} be included at the top of the YACC parser, to prevent -the various parsers from defining the same global names: - -@example -#define yyparse @var{lang}_parse -#define yylex @var{lang}_lex -#define yyerror @var{lang}_error -#define yylval @var{lang}_lval -#define yychar @var{lang}_char -#define yydebug @var{lang}_debug -#define yypact @var{lang}_pact -#define yyr1 @var{lang}_r1 -#define yyr2 @var{lang}_r2 -#define yydef @var{lang}_def -#define yychk @var{lang}_chk -#define yypgo @var{lang}_pgo -#define yyact @var{lang}_act -#define yyexca @var{lang}_exca -#define yyerrflag @var{lang}_errflag -#define yynerrs @var{lang}_nerrs -@end example - -At the bottom of your parser, define a @code{struct language_defn} and -initialize it with the right values for your language. Define an -@code{initialize_@var{lang}} routine and have it call -@samp{add_language(@var{lang}_language_defn)} to tell the rest of GDB -that your language exists. You'll need some other supporting variables -and functions, which will be used via pointers from your -@code{@var{lang}_language_defn}. See the declaration of @code{struct -language_defn} in @file{language.h}, and the other @file{*-exp.y} files, -for more information. - -@item Add any evaluation routines, if necessary - -If you need new opcodes (that represent the operations of the language), -add them to the enumerated type in @file{expression.h}. Add support -code for these operations in @code{eval.c:evaluate_subexp()}. Add cases -for new opcodes in two functions from @file{parse.c}: -@code{prefixify_subexp()} and @code{length_of_subexp()}. These compute -the number of @code{exp_element}s that a given operation takes up. - -@item Update some existing code - -Add an enumerated identifier for your language to the enumerated type -@code{enum language} in @file{defs.h}. - -Update the routines in @file{language.c} so your language is included. These -routines include type predicates and such, which (in some cases) are -language dependent. If your language does not appear in the switch -statement, an error is reported. - -Also included in @file{language.c} is the code that updates the variable -@code{current_language}, and the routines that translate the -@code{language_@var{lang}} enumerated identifier into a printable -string. - -Update the function @code{_initialize_language} to include your language. This -function picks the default language upon startup, so is dependent upon -which languages that GDB is built for. - -Update @code{allocate_symtab} in @file{symfile.c} and/or symbol-reading -code so that the language of each symtab (source file) is set properly. -This is used to determine the language to use at each stack frame level. -Currently, the language is set based upon the extension of the source -file. If the language can be better inferred from the symbol -information, please set the language of the symtab in the symbol-reading -code. - -Add helper code to @code{expprint.c:print_subexp()} to handle any new -expression opcodes you have added to @file{expression.h}. Also, add the -printed representations of your operators to @code{op_print_tab}. - -@item Add a place of call - -Add a call to @code{@var{lang}_parse()} and @code{@var{lang}_error} in -@code{parse.c:parse_exp_1()}. - -@item Use macros to trim code - -The user has the option of building GDB for some or all of the -languages. If the user decides to build GDB for the language -@var{lang}, then every file dependent on @file{language.h} will have the -macro @code{_LANG_@var{lang}} defined in it. Use @code{#ifdef}s to -leave out large routines that the user won't need if he or she is not -using your language. - -Note that you do not need to do this in your YACC parser, since if GDB -is not build for @var{lang}, then @file{@var{lang}-exp.tab.o} (the -compiled form of your parser) is not linked into GDB at all. - -See the file @file{configure.in} for how GDB is configured for different -languages. - -@item Edit @file{Makefile.in} - -Add dependencies in @file{Makefile.in}. Make sure you update the macro -variables such as @code{HFILES} and @code{OBJS}, otherwise your code may -not get linked in, or, worse yet, it may not get @code{tar}red into the -distribution! -@end table - - -@node Releases -@chapter Configuring GDB for Release - -From the top level directory (containing @file{gdb}, @file{bfd}, -@file{libiberty}, and so on): -@example -make -f Makefile.in gdb.tar.Z -@end example - -This will properly configure, clean, rebuild any files that are -distributed pre-built (e.g. @file{c-exp.tab.c} or @file{refcard.ps}), -and will then make a tarfile. (If the top level directory has already -beenn configured, you can just do @code{make gdb.tar.Z} instead.) - -This procedure requires: -@itemize @bullet -@item symbolic links -@item @code{makeinfo} (texinfo2 level) -@item @TeX{} -@item @code{dvips} -@item @code{yacc} or @code{bison} -@end itemize -@noindent -@dots{} and the usual slew of utilities (@code{sed}, @code{tar}, etc.). - -@subheading TEMPORARY RELEASE PROCEDURE FOR DOCUMENTATION - -@file{gdb.texinfo} is currently marked up using the texinfo-2 macros, -which are not yet a default for anything (but we have to start using -them sometime). - -For making paper, the only thing this implies is the right generation of -@file{texinfo.tex} needs to be included in the distribution. - -For making info files, however, rather than duplicating the texinfo2 -distribution, generate @file{gdb-all.texinfo} locally, and include the files -@file{gdb.info*} in the distribution. Note the plural; @code{makeinfo} will -split the document into one overall file and five or so included files. - - -@node Partial Symbol Tables -@chapter Partial Symbol Tables - -GDB has three types of symbol tables. - -@itemize @bullet -@item full symbol tables (symtabs). These contain the main -information about symbols and addresses. -@item partial symbol tables (psymtabs). These contain enough -information to know when to read the corresponding -part of the full symbol table. -@item minimal symbol tables (msymtabs). These contain information -gleaned from non-debugging symbols. -@end itemize - -This section describes partial symbol tables. - -A psymtab is constructed by doing a very quick pass over an executable -file's debugging information. Small amounts of information are -extracted -- enough to identify which parts of the symbol table will -need to be re-read and fully digested later, when the user needs the -information. The speed of this pass causes GDB to start up very -quickly. Later, as the detailed rereading occurs, it occurs in small -pieces, at various times, and the delay therefrom is mostly invisible to -the user. (@xref{Symbol Reading}.) - -The symbols that show up in a file's psymtab should be, roughly, those -visible to the debugger's user when the program is not running code from -that file. These include external symbols and types, static -symbols and types, and enum values declared at file scope. - -The psymtab also contains the range of instruction addresses that the -full symbol table would represent. - -The idea is that there are only two ways for the user (or much of -the code in the debugger) to reference a symbol: - -@itemize @bullet - -@item by its address -(e.g. execution stops at some address which is inside a function -in this file). The address will be noticed to be in the -range of this psymtab, and the full symtab will be read in. -@code{find_pc_function}, @code{find_pc_line}, and other @code{find_pc_@dots{}} -functions handle this. - -@item by its name -(e.g. the user asks to print a variable, or set a breakpoint on a -function). Global names and file-scope names will be found in the -psymtab, which will cause the symtab to be pulled in. Local names will -have to be qualified by a global name, or a file-scope name, in which -case we will have already read in the symtab as we evaluated the -qualifier. Or, a local symbol can be referenced when -we are "in" a local scope, in which case the first case applies. -@code{lookup_symbol} does most of the work here. - -@end itemize - -The only reason that psymtabs exist is to cause a symtab to be read in -at the right moment. Any symbol that can be elided from a psymtab, -while still causing that to happen, should not appear in it. Since -psymtabs don't have the idea of scope, you can't put local symbols in -them anyway. Psymtabs don't have the idea of the type of a symbol, -either, so types need not appear, unless they will be referenced by -name. - -It is a bug for GDB to behave one way when only a psymtab has been read, -and another way if the corresponding symtab has been read in. Such -bugs are typically caused by a psymtab that does not contain all the -visible symbols, or which has the wrong instruction address ranges. - -The psymtab for a particular section of a symbol-file (objfile) -could be thrown away after the symtab has been read in. The symtab -should always be searched before the psymtab, so the psymtab will -never be used (in a bug-free environment). Currently, -psymtabs are allocated on an obstack, and all the psymbols themselves -are allocated in a pair of large arrays on an obstack, so there is -little to be gained by trying to free them unless you want to do a lot -more work. - -@node Types -@chapter Types - -Fundamental Types (e.g., FT_VOID, FT_BOOLEAN). - -These are the fundamental types that GDB uses internally. Fundamental -types from the various debugging formats (stabs, ELF, etc) are mapped into -one of these. They are basically a union of all fundamental types that -gdb knows about for all the languages that GDB knows about. - -Type Codes (e.g., TYPE_CODE_PTR, TYPE_CODE_ARRAY). - -Each time GDB builds an internal type, it marks it with one of these -types. The type may be a fundamental type, such as TYPE_CODE_INT, or -a derived type, such as TYPE_CODE_PTR which is a pointer to another -type. Typically, several FT_* types map to one TYPE_CODE_* type, and -are distinguished by other members of the type struct, such as whether -the type is signed or unsigned, and how many bits it uses. - -Builtin Types (e.g., builtin_type_void, builtin_type_char). - -These are instances of type structs that roughly correspond to fundamental -types and are created as global types for GDB to use for various ugly -historical reasons. We eventually want to eliminate these. Note for -example that builtin_type_int initialized in gdbtypes.c is basically the -same as a TYPE_CODE_INT type that is initialized in c-lang.c for an -FT_INTEGER fundamental type. The difference is that the builtin_type is -not associated with any particular objfile, and only one instance exists, -while c-lang.c builds as many TYPE_CODE_INT types as needed, with each -one associated with some particular objfile. - -@node BFD support for GDB -@chapter Binary File Descriptor Library Support for GDB - -BFD provides support for GDB in several ways: - -@table @emph -@item identifying executable and core files -BFD will identify a variety of file types, including a.out, coff, and -several variants thereof, as well as several kinds of core files. - -@item access to sections of files -BFD parses the file headers to determine the names, virtual addresses, -sizes, and file locations of all the various named sections in files -(such as the text section or the data section). GDB simply calls -BFD to read or write section X at byte offset Y for length Z. - -@item specialized core file support -BFD provides routines to determine the failing command name stored -in a core file, the signal with which the program failed, and whether -a core file matches (i.e. could be a core dump of) a particular executable -file. - -@item locating the symbol information -GDB uses an internal interface of BFD to determine where to find the -symbol information in an executable file or symbol-file. GDB itself -handles the reading of symbols, since BFD does not ``understand'' debug -symbols, but GDB uses BFD's cached information to find the symbols, -string table, etc. -@end table - -@c The interface for symbol reading is described in @ref{Symbol -@c Reading,,Symbol Reading}. - - -@node Symbol Reading -@chapter Symbol Reading - -GDB reads symbols from "symbol files". The usual symbol file is the -file containing the program which GDB is debugging. GDB can be directed -to use a different file for symbols (with the ``symbol-file'' -command), and it can also read more symbols via the ``add-file'' and ``load'' -commands, or while reading symbols from shared libraries. - -Symbol files are initially opened by @file{symfile.c} using the BFD -library. BFD identifies the type of the file by examining its header. -@code{symfile_init} then uses this identification to locate a -set of symbol-reading functions. - -Symbol reading modules identify themselves to GDB by calling -@code{add_symtab_fns} during their module initialization. The argument -to @code{add_symtab_fns} is a @code{struct sym_fns} which contains -the name (or name prefix) of the symbol format, the length of the prefix, -and pointers to four functions. These functions are called at various -times to process symbol-files whose identification matches the specified -prefix. - -The functions supplied by each module are: - -@table @code -@item @var{xxx}_symfile_init(struct sym_fns *sf) - -Called from @code{symbol_file_add} when we are about to read a new -symbol file. This function should clean up any internal state -(possibly resulting from half-read previous files, for example) -and prepare to read a new symbol file. Note that the symbol file -which we are reading might be a new "main" symbol file, or might -be a secondary symbol file whose symbols are being added to the -existing symbol table. - -The argument to @code{@var{xxx}_symfile_init} is a newly allocated -@code{struct sym_fns} whose @code{bfd} field contains the BFD -for the new symbol file being read. Its @code{private} field -has been zeroed, and can be modified as desired. Typically, -a struct of private information will be @code{malloc}'d, and -a pointer to it will be placed in the @code{private} field. - -There is no result from @code{@var{xxx}_symfile_init}, but it can call -@code{error} if it detects an unavoidable problem. - -@item @var{xxx}_new_init() - -Called from @code{symbol_file_add} when discarding existing symbols. -This function need only handle -the symbol-reading module's internal state; the symbol table data -structures visible to the rest of GDB will be discarded by -@code{symbol_file_add}. It has no arguments and no result. -It may be called after @code{@var{xxx}_symfile_init}, if a new symbol -table is being read, or may be called alone if all symbols are -simply being discarded. - -@item @var{xxx}_symfile_read(struct sym_fns *sf, CORE_ADDR addr, int mainline) - -Called from @code{symbol_file_add} to actually read the symbols from a -symbol-file into a set of psymtabs or symtabs. - -@code{sf} points to the struct sym_fns originally passed to -@code{@var{xxx}_sym_init} for possible initialization. @code{addr} is the -offset between the file's specified start address and its true address -in memory. @code{mainline} is 1 if this is the main symbol table being -read, and 0 if a secondary symbol file (e.g. shared library or -dynamically loaded file) is being read.@refill -@end table - -In addition, if a symbol-reading module creates psymtabs when -@var{xxx}_symfile_read is called, these psymtabs will contain a pointer to -a function @code{@var{xxx}_psymtab_to_symtab}, which can be called from -any point in the GDB symbol-handling code. - -@table @code -@item @var{xxx}_psymtab_to_symtab (struct partial_symtab *pst) - -Called from @code{psymtab_to_symtab} (or the PSYMTAB_TO_SYMTAB -macro) if the psymtab has not already been read in and had its -@code{pst->symtab} pointer set. The argument is the psymtab -to be fleshed-out into a symtab. Upon return, pst->readin -should have been set to 1, and pst->symtab should contain a -pointer to the new corresponding symtab, or zero if there -were no symbols in that part of the symbol file. -@end table - - -@node Cleanups -@chapter Cleanups - -Cleanups are a structured way to deal with things that need to be done -later. When your code does something (like @code{malloc} some memory, or open -a file) that needs to be undone later (e.g. free the memory or close -the file), it can make a cleanup. The cleanup will be done at some -future point: when the command is finished, when an error occurs, or -when your code decides it's time to do cleanups. - -You can also discard cleanups, that is, throw them away without doing -what they say. This is only done if you ask that it be done. - -Syntax: - -@table @code -@item struct cleanup *@var{old_chain}; -Declare a variable which will hold a cleanup chain handle. - -@item @var{old_chain} = make_cleanup (@var{function}, @var{arg}); -Make a cleanup which will cause @var{function} to be called with @var{arg} -(a @code{char *}) later. The result, @var{old_chain}, is a handle that can be -passed to @code{do_cleanups} or @code{discard_cleanups} later. Unless you are -going to call @code{do_cleanups} or @code{discard_cleanups} yourself, -you can ignore the result from @code{make_cleanup}. - - -@item do_cleanups (@var{old_chain}); -Perform all cleanups done since @code{make_cleanup} returned @var{old_chain}. -E.g.: -@example -make_cleanup (a, 0); -old = make_cleanup (b, 0); -do_cleanups (old); -@end example -@noindent -will call @code{b()} but will not call @code{a()}. The cleanup that calls @code{a()} will remain -in the cleanup chain, and will be done later unless otherwise discarded.@refill - -@item discard_cleanups (@var{old_chain}); -Same as @code{do_cleanups} except that it just removes the cleanups from the -chain and does not call the specified functions. - -@end table - -Some functions, e.g. @code{fputs_filtered()} or @code{error()}, specify that they -``should not be called when cleanups are not in place''. This means -that any actions you need to reverse in the case of an error or -interruption must be on the cleanup chain before you call these functions, -since they might never return to your code (they @samp{longjmp} instead). - - -@node Wrapping -@chapter Wrapping Output Lines - -Output that goes through @code{printf_filtered} or @code{fputs_filtered} or -@code{fputs_demangled} needs only to have calls to @code{wrap_here} added -in places that would be good breaking points. The utility routines -will take care of actually wrapping if the line width is exceeded. - -The argument to @code{wrap_here} is an indentation string which is printed -@emph{only} if the line breaks there. This argument is saved away and used -later. It must remain valid until the next call to @code{wrap_here} or -until a newline has been printed through the @code{*_filtered} functions. -Don't pass in a local variable and then return! - -It is usually best to call @code{wrap_here()} after printing a comma or space. -If you call it before printing a space, make sure that your indentation -properly accounts for the leading space that will print if the line wraps -there. - -Any function or set of functions that produce filtered output must finish -by printing a newline, to flush the wrap buffer, before switching to -unfiltered (``@code{printf}'') output. Symbol reading routines that print -warnings are a good example. - - -@node Frames -@chapter Frames - -A frame is a construct that GDB uses to keep track of calling and called -functions. - -@table @code -@item FRAME_FP -in the machine description has no meaning to the machine-independent -part of GDB, except that it is used when setting up a new frame from -scratch, as follows: - -@example - create_new_frame (read_register (FP_REGNUM), read_pc ())); -@end example - -Other than that, all the meaning imparted to @code{FP_REGNUM} is imparted by -the machine-dependent code. So, @code{FP_REGNUM} can have any value that -is convenient for the code that creates new frames. (@code{create_new_frame} -calls @code{INIT_EXTRA_FRAME_INFO} if it is defined; that is where you should -use the @code{FP_REGNUM} value, if your frames are nonstandard.) - -@item FRAME_CHAIN -Given a GDB frame, determine the address of the calling function's -frame. This will be used to create a new GDB frame struct, and then -@code{INIT_EXTRA_FRAME_INFO} and @code{INIT_FRAME_PC} will be called for -the new frame. -@end table - -@node Remote Stubs -@chapter Remote Stubs - -GDB's file @file{remote.c} talks a serial protocol to code that runs -in the target system. GDB provides several sample ``stubs'' that can -be integrated into target programs or operating systems for this purpose; -they are named @file{*-stub.c}. - -The GDB user's manual describes how to put such a stub into your target -code. What follows is a discussion of integrating the SPARC stub -into a complicated operating system (rather than a simple program), -by Stu Grossman, the author of this stub. - -The trap handling code in the stub assumes the following upon entry to -trap_low: - -@enumerate -@item %l1 and %l2 contain pc and npc respectively at the time of the trap -@item traps are disabled -@item you are in the correct trap window -@end enumerate - -As long as your trap handler can guarantee those conditions, then there is no -reason why you shouldn't be able to `share' traps with the stub. The stub has -no requirement that it be jumped to directly from the hardware trap vector. -That is why it calls @code{exceptionHandler()}, which is provided by the external -environment. For instance, this could setup the hardware traps to actually -execute code which calls the stub first, and then transfers to its own trap -handler. - -For the most point, there probably won't be much of an issue with `sharing' -traps, as the traps we use are usually not used by the kernel, and often -indicate unrecoverable error conditions. Anyway, this is all controlled by a -table, and is trivial to modify. -The most important trap for us is for @code{ta 1}. Without that, we -can't single step or do breakpoints. Everything else is unnecessary -for the proper operation of the debugger/stub. - -From reading the stub, it's probably not obvious how breakpoints work. They -are simply done by deposit/examine operations from GDB. - -@node Longjmp Support -@chapter Longjmp Support - -GDB has support for figuring out that the target is doing a -@code{longjmp} and for stopping at the target of the jump, if we are -stepping. This is done with a few specialized internal breakpoints, -which are visible in the @code{maint info breakpoint} command. - -To make this work, you need to define a macro called -@code{GET_LONGJMP_TARGET}, which will examine the @code{jmp_buf} -structure and extract the longjmp target address. Since @code{jmp_buf} -is target specific, you will need to define it in the appropriate -@file{tm-xxx.h} file. Look in @file{tm-sun4os4.h} and -@file{sparc-tdep.c} for examples of how to do this. - -@node Coding Style -@chapter Coding Style - -GDB is generally written using the GNU coding standards, as described in -@file{standards.texi}, which is available for anonymous FTP from GNU -archive sites. There are some additional considerations for GDB -maintainers that reflect the unique environment and style of GDB -maintenance. If you follow these guidelines, GDB will be more -consistent and easier to maintain. - -GDB's policy on the use of prototypes is that prototypes are used -to @emph{declare} functions but never to @emph{define} them. Simple -macros are used in the declarations, so that a non-ANSI compiler can -compile GDB without trouble. The simple macro calls are used like -this: - -@example @code -extern int -memory_remove_breakpoint PARAMS ((CORE_ADDR, char *)); -@end example - -Note the double parentheses around the parameter types. This allows -an arbitrary number of parameters to be described, without freaking -out the C preprocessor. When the function has no parameters, it -should be described like: - -@example @code -void -noprocess PARAMS ((void)); -@end example - -The @code{PARAMS} macro expands to its argument in ANSI C, or to a simple -@code{()} in traditional C. - -All external functions should have a @code{PARAMS} declaration in a -header file that callers include. All static functions should have such -a declaration near the top of their source file. - -We don't have a gcc option that will properly check that these rules -have been followed, but it's GDB policy, and we periodically check it -using the tools available (plus manual labor), and clean up any remnants. - -@node Clean Design -@chapter Clean Design - -In addition to getting the syntax right, there's the little question of -semantics. Some things are done in certain ways in GDB because long -experience has shown that the more obvious ways caused various kinds of -trouble. In particular: - -@table @bullet -@item -You can't assume the byte order of anything that comes from a -target (including @var{value}s, object files, and instructions). Such -things must be byte-swapped using @code{SWAP_TARGET_AND_HOST} in GDB, -or one of the swap routines defined in @file{bfd.h}, such as @code{bfd_get_32}. - -@item -You can't assume that you know what interface is being used to talk to -the target system. All references to the target must go through the -current @code{target_ops} vector. - -@item -You can't assume that the host and target machines are the same machine -(except in the ``native'' support modules). -In particular, you can't assume that the target machine's header files -will be available on the host machine. Target code must bring along its -own header files -- written from scratch or explicitly donated by their -owner, to avoid copyright problems. - -@item -Insertion of new @code{#ifdef}'s will be frowned upon. It's much better -to write the code portably than to conditionalize it for various systems. - -@item -New @code{#ifdef}'s which test for specific compilers or manufacturers -or operating systems are unacceptable. All @code{#ifdef}'s should test -for features. The information about which configurations contain which -features should be segregated into the configuration files. Experience -has proven far too often that a feature unique to one particular system -often creeps into other systems; and that a conditional based on -some predefined macro for your current system will become worthless -over time, as new versions of your system come out that behave differently -with regard to this feature. - -@item -Adding code that handles specific architectures, operating systems, target -interfaces, or hosts, is not acceptable in generic code. If a hook -is needed at that point, invent a generic hook and define it for your -configuration, with something like: - -@example -#ifdef WRANGLE_SIGNALS - WRANGLE_SIGNALS (signo); -#endif -@end example - -In your host, target, or native configuration file, as appropriate, -define @code{WRANGLE_SIGNALS} to do the machine-dependent thing. Take -a bit of care in defining the hook, so that it can be used by other -ports in the future, if they need a hook in the same place. - -If the hook is not defined, the code should do whatever "most" machines -want. Using @code{#ifdef}, as above, is the preferred way to do this, -but sometimes that gets convoluted, in which case use - -@example -#ifndef SPECIAL_FOO_HANDLING -#define SPECIAL_FOO_HANDLING(pc, sp) (0) -#endif -@end example - -where the macro is used or in an appropriate header file. - -Whether to include a @dfn{small} hook, a hook around the exact pieces of -code which are system-dependent, or whether to replace a whole function -with a hook depends on the case. A good example of this dilemma can be -found in @code{get_saved_register}. All machines that GDB 2.8 ran on -just needed the @code{FRAME_FIND_SAVED_REGS} hook to find the saved -registers. Then the SPARC and Pyramid came along, and -@code{HAVE_REGISTER_WINDOWS} and @code{REGISTER_IN_WINDOW_P} were -introduced. Then the 29k and 88k required the @code{GET_SAVED_REGISTER} -hook. The first three are examples of small hooks; the latter replaces -a whole function. In this specific case, it is useful to have both -kinds; it would be a bad idea to replace all the uses of the small hooks -with @code{GET_SAVED_REGISTER}, since that would result in much -duplicated code. Other times, duplicating a few lines of code here or -there is much cleaner than introducing a large number of small hooks. - -Another way to generalize GDB along a particular interface is with an -attribute struct. For example, GDB has been generalized to handle -multiple kinds of remote interfaces -- not by #ifdef's everywhere, but -by defining the "target_ops" structure and having a current target (as -well as a stack of targets below it, for memory references). Whenever -something needs to be done that depends on which remote interface we are -using, a flag in the current target_ops structure is tested (e.g. -`target_has_stack'), or a function is called through a pointer in the -current target_ops structure. In this way, when a new remote interface -is added, only one module needs to be touched -- the one that actually -implements the new remote interface. Other examples of -attribute-structs are BFD access to multiple kinds of object file -formats, or GDB's access to multiple source languages. - -Please avoid duplicating code. For example, in GDB 3.x all the code -interfacing between @code{ptrace} and the rest of GDB was duplicated in -@file{*-dep.c}, and so changing something was very painful. In GDB 4.x, -these have all been consolidated into @file{infptrace.c}. -@file{infptrace.c} can deal with variations between systems the same way -any system-independent file would (hooks, #if defined, etc.), and -machines which are radically different don't need to use infptrace.c at -all. - -@item -@emph{Do} write code that doesn't depend on the sizes of C data types, -the format of the host's floating point numbers, the alignment of anything, -or the order of evaluation of expressions. In short, follow good -programming practices for writing portable C code. - -@end table - -@node Submitting Patches -@chapter Submitting Patches - -Thanks for thinking of offering your changes back to the community of -GDB users. In general we like to get well designed enhancements. -Thanks also for checking in advance about the best way to transfer the -changes. - -The two main problems with getting your patches in are, - -@table @bullet -@item -The GDB maintainers will only install ``cleanly designed'' patches. -You may not always agree on what is clean design. -@pxref{Coding Style}, @pxref{Clean Design}. - -@item -If the maintainers don't have time to put the patch in when it -arrives, or if there is any question about a patch, it -goes into a large queue with everyone else's patches and -bug reports. -@end table - -I don't know how to get past these problems except by continuing to try. - -There are two issues here -- technical and legal. - -The legal issue is that to incorporate substantial changes requires a -copyright assignment from you and/or your employer, granting ownership -of the changes to the Free Software Foundation. You can get the -standard document for doing this by sending mail to -@code{gnu@@prep.ai.mit.edu} and asking for it. I recommend that people -write in "All programs owned by the Free Software Foundation" as "NAME -OF PROGRAM", so that changes in many programs (not just GDB, but GAS, -Emacs, GCC, etc) can be contributed with only one piece of legalese -pushed through the bureacracy and filed with the FSF. I can't start -merging changes until this paperwork is received by the FSF (their -rules, which I follow since I maintain it for them). - -Technically, the easiest way to receive changes is to receive each -feature as a small context diff or unidiff, suitable for "patch". -Each message sent to me should include the changes to C code and -header files for a single feature, plus ChangeLog entries for each -directory where files were modified, and diffs for any changes needed -to the manuals (gdb/doc/gdb.texi or gdb/doc/gdbint.texi). If there -are a lot of changes for a single feature, they can be split down -into multiple messages. - -In this way, if I read and like the feature, I can add it to the -sources with a single patch command, do some testing, and check it in. -If you leave out the ChangeLog, I have to write one. If you leave -out the doc, I have to puzzle out what needs documenting. Etc. - -The reason to send each change in a separate message is that I will -not install some of the changes. They'll be returned to you with -questions or comments. If I'm doing my job, my message back to you -will say what you have to fix in order to make the change acceptable. -The reason to have separate messages for separate features is so -that other changes (which I @emph{am} willing to accept) can be installed -while one or more changes are being reworked. If multiple features -are sent in a single message, I tend to not put in the effort to sort -out the acceptable changes from the unacceptable, so none of the -features get installed until all are acceptable. - -If this sounds painful or authoritarian, well, it is. But I get a lot -of bug reports and a lot of patches, and most of them don't get -installed because I don't have the time to finish the job that the bug -reporter or the contributor could have done. Patches that arrive -complete, working, and well designed, tend to get installed on the day -they arrive. The others go into a queue and get installed if and when -I scan back over the queue -- which can literally take months -sometimes. It's in both our interests to make patch installation easy --- you get your changes installed, and I make some forward progress on -GDB in a normal 12-hour day (instead of them having to wait until I -have a 14-hour or 16-hour day to spend cleaning up patches before I -can install them). - -Please send patches to @code{bug-gdb@@prep.ai.mit.edu}, if they are less -than about 25,000 characters. If longer than that, either make them -available somehow (e.g. anonymous FTP), and announce it on -@code{bug-gdb}, or send them directly to the GDB maintainers at -@code{gdb-patches@@cygnus.com}. - -@node Host Conditionals -@chapter Host Conditionals - -When GDB is configured and compiled, various macros are defined or left -undefined, to control compilation based on the attributes of the host -system. These macros and their meanings (or if the meaning is not -documented here, then one of the source files where they are used is -indicated) are: - -@emph{NOTE: For now, both host and target conditionals are here. -Eliminate target conditionals from this list as they are identified.} - -@table @code - -@item BLOCK_ADDRESS_FUNCTION_RELATIVE -dbxread.c - -@item GDBINIT_FILENAME -The default name of GDB's initialization file (normally @file{.gdbinit}). - -@item KERNELDEBUG -tm-hppa.h - -@item MEM_FNS_DECLARED -Your host config file defines this if it includes -declarations of @code{memcpy} and @code{memset}. Define this -to avoid conflicts between the native include -files and the declarations in @file{defs.h}. - -@item NO_SYS_FILE -dbxread.c -@item PYRAMID_CONTROL_FRAME_DEBUGGING -pyr-xdep.c -@item SIGWINCH_HANDLER_BODY -utils.c -@item ADDITIONAL_OPTIONS -main.c -@item ADDITIONAL_OPTION_CASES -main.c -@item ADDITIONAL_OPTION_HANDLER -main.c -@item ADDITIONAL_OPTION_HELP -main.c -@item ADDR_BITS_REMOVE -defs.h -@item AIX_BUGGY_PTRACE_CONTINUE -infptrace.c -@item ALIGN_STACK_ON_STARTUP -main.c -@item ALTOS -altos-xdep.c -@item ALTOS_AS -xm-altos.h -@item ASCII_COFF -remote-adapt.c -@item BCS -tm-delta88.h -@item BEFORE_MAIN_LOOP_HOOK -main.c -@item BELIEVE_PCC_PROMOTION -coffread.c -@item BELIEVE_PCC_PROMOTION_TYPE -stabsread.c -@item BITS_BIG_ENDIAN -defs.h -@item BKPT_AT_MAIN -solib.c -@item BLOCK_ADDRESS_ABSOLUTE -dbxread.c -@item BPT_VECTOR -tm-m68k.h - -@item BROKEN_LARGE_ALLOCA -Avoid large @code{alloca}'s. For example, on sun's, Large alloca's fail -because the attempt to increase the stack limit in main() fails because -shared libraries are allocated just below the initial stack limit. The -SunOS kernel will not allow the stack to grow into the area occupied by -the shared libraries. - -@item CALL_DUMMY -valops.c -@item CALL_DUMMY_LOCATION -inferior.h -@item CALL_DUMMY_STACK_ADJUST -valops.c -@item CFRONT_PRODUCER -dwarfread.c -@item CHILD_PREPARE_TO_STORE -inftarg.c -@item CLEAR_DEFERRED_STORES -inflow.c -@item CLEAR_SOLIB -objfiles.c -@item COFF_ENCAPSULATE -hppabsd-tdep.c -@item COFF_FORMAT -symm-tdep.c -@item CORE_NEEDS_RELOCATION -stack.c -@item CPLUS_MARKER -cplus-dem.c -@item C_ALLOCA -regex.c -@item C_GLBLREG -coffread.c -@item DBXREAD_ONLY -partial-stab.h -@item DBX_PARM_SYMBOL_CLASS -stabsread.c -@item DEBUG_INFO -partial-stab.h -@item DEBUG_PTRACE -hppabsd-xdep.c -@item DECR_PC_AFTER_BREAK -breakpoint.c - -@item DEFAULT_PROMPT -The default value of the prompt string (normally @code{"(gdb) "}). - -@item DELTA88 -m88k-xdep.c -@item DEV_TTY -symmisc.c -@item DGUX -m88k-xdep.c -@item DISABLE_UNSETTABLE_BREAK -breakpoint.c -@item DONT_USE_REMOTE -remote.c -@item DO_DEFERRED_STORES -infrun.c -@item DO_REGISTERS_INFO -infcmd.c -@item EXTRACT_RETURN_VALUE -tm-m68k.h -@item EXTRACT_STRUCT_VALUE_ADDRESS -values.c -@item EXTRA_FRAME_INFO -frame.h -@item EXTRA_SYMTAB_INFO -symtab.h -@item FILES_INFO_HOOK -target.c -@item FLOAT_INFO -infcmd.c -@item FOPEN_RB -defs.h -@item FUNCTION_EPILOGUE_SIZE -coffread.c -@item F_OK -xm-ultra3.h -@item GCC2_COMPILED_FLAG_SYMBOL -dbxread.c -@item GCC_COMPILED_FLAG_SYMBOL -dbxread.c -@item GCC_MANGLE_BUG -symtab.c -@item GCC_PRODUCER -dwarfread.c -@item GET_SAVED_REGISTER -findvar.c -@item GPLUS_PRODUCER -dwarfread.c -@item HANDLE_RBRAC -partial-stab.h - -@item HAVE_MMAP -In some cases, use the system call @code{mmap} for reading symbol -tables. For some machines this allows for sharing and quick updates. - -@item HAVE_REGISTER_WINDOWS -findvar.c -@item HAVE_SIGSETMASK -main.c -@item HAVE_TERMIO -inflow.c -@item HEADER_SEEK_FD -arm-tdep.c -@item HOSTING_ONLY -xm-rtbsd.h -@item HOST_BYTE_ORDER -findvar.c -@item HPUX_ASM -xm-hp300hpux.h -@item HPUX_VERSION_5 -hp300ux-xdep.c -@item HP_OS_BUG -infrun.c -@item I80960 -remote-vx.c -@item IEEE_FLOAT -valprint.c -@item IGNORE_SYMBOL -dbxread.c -@item INIT_EXTRA_FRAME_INFO -blockframe.c -@item INIT_EXTRA_SYMTAB_INFO -symfile.c -@item INIT_FRAME_PC -blockframe.c -@item INNER_THAN -valops.c -@item INT_MAX -defs.h -@item INT_MIN -defs.h -@item IN_GDB -i960-pinsn.c -@item IN_SIGTRAMP -infrun.c -@item IN_SOLIB_TRAMPOLINE -infrun.c -@item ISATTY -main.c -@item IS_TRAPPED_INTERNALVAR -values.c -@item KERNELDEBUG -dbxread.c -@item KERNEL_DEBUGGING -tm-ultra3.h - -@item KERNEL_U_ADDR -Define this to the address of the @code{u} structure (the ``user struct'', -also known as the ``u-page'') in kernel virtual memory. GDB needs to know -this so that it can subtract this address from absolute addresses in -the upage, that are obtained via ptrace or from core files. On systems -that don't need this value, set it to zero. - -@item KERNEL_U_ADDR_BSD -Define this to cause GDB to determine the address of @code{u} at runtime, -by using Berkeley-style @code{nlist} on the kernel's image in the root -directory. - -@item KERNEL_U_ADDR_HPUX -Define this to cause GDB to determine the address of @code{u} at runtime, -by using HP-style @code{nlist} on the kernel's image in the root -directory. - -@item LCC_PRODUCER -dwarfread.c -@item LOG_FILE -remote-adapt.c -@item LONGERNAMES -cplus-dem.c -@item LONGEST -defs.h -@item CC_HAS_LONG_LONG -defs.h -@item PRINTF_HAS_LONG_LONG -defs.h -@item LONG_MAX -defs.h -@item LSEEK_NOT_LINEAR -source.c -@item L_LNNO32 -coffread.c - -@item L_SET -This macro is used as the argument to lseek (or, most commonly, bfd_seek). -FIXME, should be replaced by SEEK_SET instead, which is the POSIX equivalent. - -@item MACHKERNELDEBUG -hppabsd-tdep.c -@item MAINTENANCE -dwarfread.c - -@item MAINTENANCE_CMDS -If the value of this is 1, then a number of optional maintenance commands -are compiled in. - -@item MALLOC_INCOMPATIBLE -Define this if the system's prototype for @code{malloc} differs from the -@sc{ANSI} definition. - -@item MIPSEL -mips-tdep.c - -@item MMAP_BASE_ADDRESS -When using HAVE_MMAP, the first mapping should go at this address. - -@item MMAP_INCREMENT -when using HAVE_MMAP, this is the increment between mappings. - -@item MONO -ser-go32.c -@item MOTOROLA -xm-altos.h -@item NBPG -altos-xdep.c -@item NEED_POSIX_SETPGID -infrun.c -@item NEED_TEXT_START_END -exec.c -@item NFAILURES -regex.c - -@item NORETURN -(in defs.h - is this really useful to define/undefine?) - -@item NOTDEF -regex.c -@item NOTDEF -remote-adapt.c -@item NOTDEF -remote-mm.c -@item NOTICE_SIGNAL_HANDLING_CHANGE -infrun.c -@item NO_HIF_SUPPORT -remote-mm.c -@item NO_JOB_CONTROL -signals.h - -@item NO_MMALLOC -GDB will use the @code{mmalloc} library for memory allocation for symbol -reading, unless this symbol is defined. Define it on systems -on which @code{mmalloc} does not -work for some reason. One example is the DECstation, where its RPC -library can't cope with our redefinition of @code{malloc} to call -@code{mmalloc}. When defining @code{NO_MMALLOC}, you will also have -to override the setting of @code{MMALLOC_LIB} to empty, in the Makefile. -Therefore, this define is usually set on the command line by overriding -@code{MMALLOC_DISABLE} in @file{config/*/*.mh}, rather than by defining -it in @file{xm-*.h}. - -@item NO_MMALLOC_CHECK -Define this if you are using @code{mmalloc}, but don't want the overhead -of checking the heap with @code{mmcheck}. - -@item NO_SIGINTERRUPT -remote-adapt.c -@item NO_SINGLE_STEP -infptrace.c -@item NS32K_SVC_IMMED_OPERANDS -ns32k-opcode.h -@item NUMERIC_REG_NAMES -mips-tdep.c -@item N_SETV -dbxread.c -@item N_SET_MAGIC -hppabsd-tdep.c -@item NaN -tm-umax.h -@item ONE_PROCESS_WRITETEXT -breakpoint.c -@item O_BINARY -exec.c -@item O_RDONLY -xm-ultra3.h -@item PC -convx-opcode.h -@item PCC_SOL_BROKEN -dbxread.c -@item PC_IN_CALL_DUMMY -inferior.h -@item PC_LOAD_SEGMENT -stack.c -@item PRINT_RANDOM_SIGNAL -infcmd.c -@item PRINT_REGISTER_HOOK -infcmd.c -@item PRINT_TYPELESS_INTEGER -valprint.c -@item PROCESS_LINENUMBER_HOOK -buildsym.c -@item PROLOGUE_FIRSTLINE_OVERLAP -infrun.c -@item PSIGNAL_IN_SIGNAL_H -defs.h -@item PUSH_ARGUMENTS -valops.c -@item PYRAMID_CONTROL_FRAME_DEBUGGING -pyr-xdep.c -@item PYRAMID_CORE -pyr-xdep.c -@item PYRAMID_PTRACE -pyr-xdep.c -@item REGISTER_BYTES -remote.c -@item REGISTER_NAMES -tm-a29k.h -@item REG_STACK_SEGMENT -exec.c -@item REG_STRUCT_HAS_ADDR -findvar.c -@item RE_NREGS -regex.h -@item R_FP -dwarfread.c -@item R_OK -xm-altos.h -@item SEEK_END -state.c -@item SEEK_SET -state.c -@item SEM -coffread.c - -@item SET_STACK_LIMIT_HUGE -When defined, stack limits will be raised to their maximum. Use this -if your host supports @code{setrlimit} and you have trouble with -@code{stringtab} in @file{dbxread.c}. - -Also used in @file{fork-child.c} to return stack limits before child -processes are forked. - -@item SHELL_COMMAND_CONCAT -infrun.c -@item SHELL_FILE -infrun.c -@item SHIFT_INST_REGS -breakpoint.c -@item SIGN_EXTEND_CHAR -regex.c -@item SIGTRAP_STOP_AFTER_LOAD -infrun.c -@item SKIP_TRAMPOLINE_CODE -infrun.c -@item SOLIB_ADD -core.c -@item STACK_ALIGN -valops.c -@item START_INFERIOR_TRAPS_EXPECTED -infrun.c -@item STOP_SIGNAL -main.c -@item SUN4_COMPILER_FEATURE -infrun.c -@item SUN_FIXED_LBRAC_BUG -dbxread.c -@item SVR4_SHARED_LIBS -solib.c -@item SWITCH_ENUM_BUG -regex.c -@item SYM1 -tm-ultra3.h -@item SYMBOL_RELOADING_DEFAULT -symfile.c -@item SYNTAX_TABLE -regex.c -@item Sword -regex.c -@item TIOCGETC -inflow.c -@item TIOCGLTC -inflow.c -@item TIOCGPGRP -inflow.c -@item TIOCLGET -inflow.c -@item TIOCLSET -inflow.c -@item TIOCNOTTY -inflow.c -@item T_ARG -coffread.c -@item T_VOID -coffread.c -@item UINT_MAX -defs.h -@item UPAGES -altos-xdep.c -@item USER -m88k-tdep.c -@item USE_GAS -xm-news.h -@item USE_O_NOCTTY -inflow.c -@item USE_STRUCT_CONVENTION -values.c - -@item USG -Means that System V (prior to SVR4) include files are in use. -(FIXME: This symbol is abused in @file{infrun.c}, @file{regex.c}, -@file{remote-nindy.c}, and @file{utils.c} for other things, at the moment.) - -@item USIZE -xm-m88k.h -@item U_FPSTATE -i386-xdep.c -@item VARIABLES_INSIDE_BLOCK -dbxread.c -@item WRS_ORIG -remote-vx.c -@item __GNUC__ -news-xdep.c -@item __GO32__ -inflow.c -@item __HPUX_ASM__ -xm-hp300hpux.h -@item __INT_VARARGS_H -printcmd.c -@item __not_on_pyr_yet -pyr-xdep.c -@item alloca -defs.h -@item const -defs.h -@item GOULD_PN -gould-pinsn.c -@item hp800 -xm-hppabsd.h -@item hpux -hppabsd-core.c -@item lint -valarith.c -@item longest_to_int -defs.h -@item mc68020 -m68k-stub.c -@item notdef -gould-pinsn.c -@item ns32k_opcodeT -ns32k-opcode.h -@item sgi -mips-tdep.c -@item sparc -regex.c -@item sun -m68k-tdep.c -@item sun386 -tm-sun386.h -@item test -regex.c -@item ultrix -xm-mips.h -@item volatile -defs.h -@end table - -@node Target Conditionals -@chapter Target Conditionals - -When GDB is configured and compiled, various macros are defined or left -undefined, to control compilation based on the attributes of the target -system. These macros and their meanings are: - -@emph{NOTE: For now, both host and target conditionals are here. -Eliminate host conditionals from this list as they are identified.} - -@table @code - -@item PUSH_DUMMY_FRAME -Used in @samp{call_function_by_hand} to create an artificial stack frame. - -@item POP_FRAME -Used in @samp{call_function_by_hand} to remove an artificial stack frame. - -@item BLOCK_ADDRESS_FUNCTION_RELATIVE -dbxread.c -@item KERNELDEBUG -tm-hppa.h -@item NO_SYS_FILE -dbxread.c -@item PYRAMID_CONTROL_FRAME_DEBUGGING -pyr-xdep.c -@item SIGWINCH_HANDLER_BODY -utils.c -@item ADDITIONAL_OPTIONS -main.c -@item ADDITIONAL_OPTION_CASES -main.c -@item ADDITIONAL_OPTION_HANDLER -main.c -@item ADDITIONAL_OPTION_HELP -main.c -@item ADDR_BITS_REMOVE -defs.h -@item ALIGN_STACK_ON_STARTUP -main.c -@item ALTOS -altos-xdep.c -@item ALTOS_AS -xm-altos.h -@item ASCII_COFF -remote-adapt.c -@item BCS -tm-delta88.h -@item BELIEVE_PCC_PROMOTION -coffread.c -@item BELIEVE_PCC_PROMOTION_TYPE -stabsread.c -@item BITS_BIG_ENDIAN -defs.h -@item BKPT_AT_MAIN -solib.c -@item BLOCK_ADDRESS_ABSOLUTE -dbxread.c -@item BPT_VECTOR -tm-m68k.h -@item BREAKPOINT -tm-m68k.h -@item CALL_DUMMY -valops.c -@item CALL_DUMMY_LOCATION -inferior.h -@item CALL_DUMMY_STACK_ADJUST -valops.c - -@item CANNOT_FETCH_REGISTER (regno) -A C expression that should be nonzero if @var{regno} cannot be -fetched from an inferior process. -This is only relevant if @code{FETCH_INFERIOR_REGISTERS} is not -defined. - -@item CANNOT_STORE_REGISTER (regno) -A C expression that should be nonzero if @var{regno} should not be -written to the target. This is often the case for program counters, -status words, and other special registers. If this is not defined, -GDB will assume that all registers may be written. - -@item CFRONT_PRODUCER -dwarfread.c -@item CHILD_PREPARE_TO_STORE -inftarg.c -@item CLEAR_DEFERRED_STORES -inflow.c -@item CLEAR_SOLIB -objfiles.c -@item COFF_ENCAPSULATE -hppabsd-tdep.c -@item COFF_FORMAT -symm-tdep.c -@item CORE_NEEDS_RELOCATION -stack.c -@item CPLUS_MARKER -cplus-dem.c -@item C_GLBLREG -coffread.c -@item DBXREAD_ONLY -partial-stab.h -@item DBX_PARM_SYMBOL_CLASS -stabsread.c -@item DEBUG_INFO -partial-stab.h -@item DEBUG_PTRACE -hppabsd-xdep.c -@item DECR_PC_AFTER_BREAK -breakpoint.c -@item DELTA88 -m88k-xdep.c -@item DEV_TTY -symmisc.c -@item DGUX -m88k-xdep.c -@item DISABLE_UNSETTABLE_BREAK -breakpoint.c -@item DONT_USE_REMOTE -remote.c -@item DO_DEFERRED_STORES -infrun.c -@item DO_REGISTERS_INFO -infcmd.c - -@item END_OF_TEXT_DEFAULT -This is an expression that should designate the end of the text section -(? FIXME ?) - -@item EXTRACT_RETURN_VALUE -tm-m68k.h -@item EXTRACT_STRUCT_VALUE_ADDRESS -values.c -@item EXTRA_FRAME_INFO -frame.h -@item EXTRA_SYMTAB_INFO -symtab.h -@item FILES_INFO_HOOK -target.c -@item FLOAT_INFO -infcmd.c -@item FOPEN_RB -defs.h -@item FP0_REGNUM -a68v-xdep.c -@item FPC_REGNUM -mach386-xdep.c -@item FP_REGNUM -parse.c -@item FRAMELESS_FUNCTION_INVOCATION -blockframe.c -@item FRAME_ARGS_ADDRESS_CORRECT -stack.c - -@item FRAME_CHAIN -Given FRAME, return a pointer to the calling frame. - -@item FRAME_CHAIN_COMBINE -blockframe.c -@item FRAME_CHAIN_VALID -frame.h -@item FRAME_CHAIN_VALID_ALTERNATE -frame.h -@item FRAME_FIND_SAVED_REGS -stack.c -@item FRAME_GET_BASEREG_VALUE -frame.h - -@item FRAME_NUM_ARGS (val, fi) -For the frame described by fi, set val to the number of arguments -that are being passed. - -@item FRAME_SPECIFICATION_DYADIC -stack.c - -@item FRAME_SAVED_PC -Given FRAME, return the pc saved there. That is, the return address. - -@item FUNCTION_EPILOGUE_SIZE -coffread.c -@item F_OK -xm-ultra3.h -@item GCC2_COMPILED_FLAG_SYMBOL -dbxread.c -@item GCC_COMPILED_FLAG_SYMBOL -dbxread.c -@item GCC_MANGLE_BUG -symtab.c -@item GCC_PRODUCER -dwarfread.c - -@item GDB_TARGET_IS_HPPA -This determines whether horrible kludge code in dbxread.c and partial-stab.h -is used to mangle multiple-symbol-table files from HPPA's. This should all -be ripped out, and a scheme like elfread.c used. - -@item GDB_TARGET_IS_MACH386 -mach386-xdep.c -@item GDB_TARGET_IS_SUN3 -a68v-xdep.c -@item GDB_TARGET_IS_SUN386 -sun386-xdep.c - -@item GET_LONGJMP_TARGET -For most machines, this is a target-dependent parameter. On the DECstation -and the Iris, this is a native-dependent parameter, since <setjmp.h> is -needed to define it. - -This macro determines the target PC address that longjmp() will jump -to, assuming that we have just stopped at a longjmp breakpoint. It -takes a CORE_ADDR * as argument, and stores the target PC value through -this pointer. It examines the current state of the machine as needed. - -@item GET_SAVED_REGISTER -findvar.c -@item GPLUS_PRODUCER -dwarfread.c -@item GR64_REGNUM -remote-adapt.c -@item GR64_REGNUM -remote-mm.c -@item HANDLE_RBRAC -partial-stab.h -@item HAVE_68881 -m68k-tdep.c -@item HAVE_REGISTER_WINDOWS -findvar.c -@item HAVE_SIGSETMASK -main.c -@item HAVE_TERMIO -inflow.c -@item HEADER_SEEK_FD -arm-tdep.c -@item HOSTING_ONLY -xm-rtbsd.h -@item HPUX_ASM -xm-hp300hpux.h -@item HPUX_VERSION_5 -hp300ux-xdep.c -@item HP_OS_BUG -infrun.c -@item I80960 -remote-vx.c - -@item IBM6000_TARGET -Shows that we are configured for an IBM RS/6000 target. This conditional -should be eliminated (FIXME) and replaced by feature-specific macros. -It was introduced in haste and we are repenting at leisure. - -@item IEEE_FLOAT -valprint.c -@item IGNORE_SYMBOL -dbxread.c -@item INIT_EXTRA_FRAME_INFO -blockframe.c -@item INIT_EXTRA_SYMTAB_INFO -symfile.c -@item INIT_FRAME_PC -blockframe.c -@item INNER_THAN -valops.c -@item INT_MAX -defs.h -@item INT_MIN -defs.h -@item IN_GDB -i960-pinsn.c -@item IN_SIGTRAMP -infrun.c -@item IN_SOLIB_TRAMPOLINE -infrun.c -@item ISATTY -main.c -@item IS_TRAPPED_INTERNALVAR -values.c -@item KERNELDEBUG -dbxread.c -@item KERNEL_DEBUGGING -tm-ultra3.h -@item LCC_PRODUCER -dwarfread.c -@item LOG_FILE -remote-adapt.c -@item LONGERNAMES -cplus-dem.c -@item LONGEST -defs.h -@item CC_HAS_LONG_LONG -defs.h -@item PRINTF_HAS_LONG_LONG -defs.h -@item LONG_MAX -defs.h -@item L_LNNO32 -coffread.c -@item MACHKERNELDEBUG -hppabsd-tdep.c -@item MAINTENANCE -dwarfread.c -@item MIPSEL -mips-tdep.c -@item MOTOROLA -xm-altos.h -@item NBPG -altos-xdep.c -@item NEED_POSIX_SETPGID -infrun.c -@item NEED_TEXT_START_END -exec.c -@item NNPC_REGNUM -infrun.c -@item NOTDEF -remote-adapt.c -@item NOTDEF -remote-mm.c -@item NOTICE_SIGNAL_HANDLING_CHANGE -infrun.c -@item NO_HIF_SUPPORT -remote-mm.c -@item NO_SIGINTERRUPT -remote-adapt.c -@item NO_SINGLE_STEP -infptrace.c -@item NPC_REGNUM -infcmd.c -@item NS32K_SVC_IMMED_OPERANDS -ns32k-opcode.h -@item NUMERIC_REG_NAMES -mips-tdep.c -@item N_SETV -dbxread.c -@item N_SET_MAGIC -hppabsd-tdep.c -@item NaN -tm-umax.h -@item ONE_PROCESS_WRITETEXT -breakpoint.c -@item PC -convx-opcode.h -@item PCC_SOL_BROKEN -dbxread.c -@item PC_IN_CALL_DUMMY -inferior.h -@item PC_LOAD_SEGMENT -stack.c -@item PC_REGNUM -parse.c -@item PRINT_RANDOM_SIGNAL -infcmd.c -@item PRINT_REGISTER_HOOK -infcmd.c -@item PRINT_TYPELESS_INTEGER -valprint.c -@item PROCESS_LINENUMBER_HOOK -buildsym.c -@item PROLOGUE_FIRSTLINE_OVERLAP -infrun.c -@item PSIGNAL_IN_SIGNAL_H -defs.h -@item PS_REGNUM -parse.c -@item PUSH_ARGUMENTS -valops.c -@item REGISTER_BYTES -remote.c -@item REGISTER_NAMES -tm-a29k.h -@item REG_STACK_SEGMENT -exec.c -@item REG_STRUCT_HAS_ADDR -findvar.c -@item R_FP -dwarfread.c -@item R_OK -xm-altos.h - -@item SDB_REG_TO_REGNUM -Define this to convert sdb register numbers -into GDB regnums. If not defined, no conversion will be done. - -@item SEEK_END -state.c -@item SEEK_SET -state.c -@item SEM -coffread.c -@item SHELL_COMMAND_CONCAT -infrun.c -@item SHELL_FILE -infrun.c -@item SHIFT_INST_REGS -breakpoint.c -@item SIGTRAP_STOP_AFTER_LOAD -infrun.c - -@item SKIP_PROLOGUE -A C statement that advances the PC across any function entry -prologue instructions so as to reach ``real'' code. - -@item SKIP_PROLOGUE_FRAMELESS_P -A C statement that should behave similarly, but that can stop -as soon as the function is known to have a frame. -If not defined, @code{SKIP_PROLOGUE} will be used instead. - -@item SKIP_TRAMPOLINE_CODE -infrun.c -@item SOLIB_ADD -core.c -@item SP_REGNUM -parse.c - -@item STAB_REG_TO_REGNUM -Define this to convert stab register numbers (as gotten from `r' declarations) -into GDB regnums. If not defined, no conversion will be done. - -@item STACK_ALIGN -valops.c -@item START_INFERIOR_TRAPS_EXPECTED -infrun.c -@item STOP_SIGNAL -main.c - -@item STORE_RETURN_VALUE (type, valbuf) -A C expression that stores a function return value of type @var{type}, -where @var{valbuf} is the address of the value to be stored. - -@item SUN4_COMPILER_FEATURE -infrun.c -@item SUN_FIXED_LBRAC_BUG -dbxread.c -@item SVR4_SHARED_LIBS -solib.c -@item SYM1 -tm-ultra3.h -@item SYMBOL_RELOADING_DEFAULT -symfile.c - -@item TARGET_BYTE_ORDER -The ordering of bytes in the target. -This must be defined to be either @code{BIG_ENDIAN} or @code{LITTLE_ENDIAN}. - -@item TARGET_CHAR_BIT -Number of bits in a char; defaults to 8. - -@item TARGET_COMPLEX_BIT -Number of bits in a complex number; defaults to @code{2 * TARGET_FLOAT_BIT}. - -@item TARGET_DOUBLE_BIT -Number of bits in a double float; defaults to @code{8 * TARGET_CHAR_BIT}. - -@item TARGET_DOUBLE_COMPLEX_BIT -Number of bits in a double complex; defaults to @code{2 * TARGET_DOUBLE_BIT}. - -@item TARGET_FLOAT_BIT -Number of bits in a float; defaults to @code{4 * TARGET_CHAR_BIT}. - -@item TARGET_INT_BIT -Number of bits in an integer; defaults to @code{4 * TARGET_CHAR_BIT}. - -@item TARGET_LONG_BIT -Number of bits in a long integer; defaults to @code{4 * TARGET_CHAR_BIT}. - -@item TARGET_LONG_DOUBLE_BIT -Number of bits in a long double float; -defaults to @code{2 * TARGET_DOUBLE_BIT}. - -@item TARGET_LONG_LONG_BIT -Number of bits in a long long integer; defaults to @code{2 * TARGET_LONG_BIT}. - -@item TARGET_PTR_BIT -Number of bits in a pointer; defaults to @code{TARGET_INT_BIT}. - -@item TARGET_SHORT_BIT -Number of bits in a short integer; defaults to @code{2 * TARGET_CHAR_BIT}. - -@item TARGET_READ_PC -@item TARGET_WRITE_PC (val, pid) -@item TARGET_READ_SP -@item TARGET_WRITE_SP -@item TARGET_READ_FP -@item TARGET_WRITE_FP -These change the behavior of @code{read_pc}, @code{write_pc}, -@code{read_sp}, @code{write_sp}, @code{read_fp} and @code{write_fp}. -For most targets, these may be left undefined. GDB will call the -read and write register functions with the relevant @code{_REGNUM} argument. - -These macros are useful when a target keeps one of these registers in a -hard to get at place; for example, part in a segment register and part -in an ordinary register. - -@item T_ARG -coffread.c -@item T_VOID -coffread.c -@item UINT_MAX -defs.h -@item USER -m88k-tdep.c -@item USE_GAS -xm-news.h -@item USE_STRUCT_CONVENTION -values.c -@item USIZE -xm-m88k.h -@item U_FPSTATE -i386-xdep.c -@item VARIABLES_INSIDE_BLOCK -dbxread.c -@item WRS_ORIG -remote-vx.c -@item __GO32__ -inflow.c -@item __HPUX_ASM__ -xm-hp300hpux.h -@item __INT_VARARGS_H -printcmd.c -@item __not_on_pyr_yet -pyr-xdep.c -@item GOULD_PN -gould-pinsn.c -@item hp800 -xm-hppabsd.h -@item hpux -hppabsd-core.c -@item longest_to_int -defs.h -@item mc68020 -m68k-stub.c -@item ns32k_opcodeT -ns32k-opcode.h -@item sgi -mips-tdep.c -@item sun -m68k-tdep.c -@item sun386 -tm-sun386.h - -@item test -(Define this to enable testing code in regex.c.) - -@end table - -@node Native Conditionals -@chapter Native Conditionals - -When GDB is configured and compiled, various macros are defined or left -undefined, to control compilation when the host and target systems -are the same. These macros should be defined (or left undefined) -in @file{nm-@var{system}.h}. - -@table @code - -@item ATTACH_DETACH -If defined, then GDB will include support for the @code{attach} and -@code{detach} commands. - -@item FETCH_INFERIOR_REGISTERS -Define this if the native-dependent code will provide its -own routines -@code{fetch_inferior_registers} and @code{store_inferior_registers} in -@file{@var{HOST}-nat.c}. -If this symbol is @emph{not} defined, and @file{infptrace.c} -is included in this configuration, the default routines in -@file{infptrace.c} are used for these functions. - -@item GET_LONGJMP_TARGET -For most machines, this is a target-dependent parameter. On the DECstation -and the Iris, this is a native-dependent parameter, since <setjmp.h> is -needed to define it. - -This macro determines the target PC address that longjmp() will jump -to, assuming that we have just stopped at a longjmp breakpoint. It -takes a CORE_ADDR * as argument, and stores the target PC value through -this pointer. It examines the current state of the machine as needed. - -@item PROC_NAME_FMT -Defines the format for the name of a @file{/proc} device. Should be -defined in @file{nm.h} @emph{only} in order to override the default -definition in @file{procfs.c}. - -@item PTRACE_FP_BUG -mach386-xdep.c - -@item PTRACE_ARG3_TYPE -The type of the third argument to the @code{ptrace} system call, if it exists -and is different from @code{int}. - -@item REGISTER_U_ADDR -Defines the offset of the registers in the ``u area''; @pxref{Host}. - -@item SOLIB_CREATE_INFERIOR_HOOK -Define this to expand into any shared-library-relocation code -that you want to be run just after the child process has been forked. - -@item USE_PROC_FS -This determines whether small routines in @file{*-tdep.c}, which -translate register values -between GDB's internal representation and the /proc representation, -are compiled. - -@item U_REGS_OFFSET -This is the offset of the registers in the upage. It need only be -defined if the generic ptrace register access routines in -@file{infptrace.c} are being used (that is, -@file{infptrace.c} is configured in, and -@code{FETCH_INFERIOR_REGISTERS} is not defined). If the default value -from @file{infptrace.c} is good enough, leave it undefined. - -The default value means that u.u_ar0 @emph{points to} the location of the -registers. I'm guessing that @code{#define U_REGS_OFFSET 0} means that -u.u_ar0 @emph{is} the location of the registers. - -@end table - -@node Obsolete Conditionals -@chapter Obsolete Conditionals - -Fragments of old code in GDB sometimes reference or set the following -configuration macros. They should not be used by new code, and -old uses should be removed as those parts of the debugger are -otherwise touched. - -@table @code -@item STACK_END_ADDR -This macro used to define where the end of the stack appeared, for use -in interpreting core file formats that don't record this address in the -core file itself. This information is now configured in BFD, and GDB -gets the info portably from there. The values in GDB's configuration -files should be moved into BFD configuration files (if needed there), -and deleted from all of GDB's config files. - -Any @file{@var{foo}-xdep.c} file that references STACK_END_ADDR -is so old that it has never been converted to use BFD. Now that's old! -@end table - -@node XCOFF -@chapter The XCOFF Object File Format - -The IBM RS/6000 running AIX uses an object file format called xcoff. -The COFF sections, symbols, and line numbers are used, but debugging -symbols are dbx-style stabs whose strings are located in the -@samp{.debug} section (rather than the string table). For more -information, @xref{Top,,,stabs,The Stabs Debugging Format}, and search -for XCOFF. - -The shared library scheme has a nice clean interface for figuring out -what shared libraries are in use, but the catch is that everything which -refers to addresses (symbol tables and breakpoints at least) needs to be -relocated for both shared libraries and the main executable. At least -using the standard mechanism this can only be done once the program has -been run (or the core file has been read). - -@contents -@bye diff --git a/gnu/usr.bin/gdb/doc/h8-cfg.texi b/gnu/usr.bin/gdb/doc/h8-cfg.texi deleted file mode 100644 index 823c7c2..0000000 --- a/gnu/usr.bin/gdb/doc/h8-cfg.texi +++ /dev/null @@ -1,47 +0,0 @@ -@c GDB version number is recorded in the variable GDBVN -@include GDBvn.texi -@c -@set AGGLOMERATION -@clear AMD29K -@set BARETARGET -@clear CONLY -@set DOSHOST -@clear FORTRAN -@clear FSFDOC -@clear GDBSERVER -@clear GENERIC -@set H8 -@set H8EXCLUSIVE -@clear HAVE-FLOAT -@clear I960 -@clear MOD2 -@clear NOVEL -@clear POSIX -@set PRECONFIGURED -@clear REMOTESTUB -@set SIMS -@clear SERIAL -@clear SPARC -@clear ST2000 -@clear VXWORKS -@clear Z8K -@c ---------------------------------------------------------------------- -@c STRINGS: -@c -@c Name of GDB program. Used also for (gdb) prompt string. -@set GDBP gdb -@c -@c Name of GDB product. Used in running text. -@set GDBN GDB -@c -@c Name of GDB initialization file. -@set GDBINIT .gdbinit -@c -@c Name of target. -@set TARGET Hitachi Microprocessors -@c -@c Name of GCC product -@set NGCC GCC -@c -@c Name of GCC program -@set GCC gcc diff --git a/gnu/usr.bin/gdb/doc/inc-hist.texi b/gnu/usr.bin/gdb/doc/inc-hist.texi deleted file mode 100644 index 539e372..0000000 --- a/gnu/usr.bin/gdb/doc/inc-hist.texi +++ /dev/null @@ -1,155 +0,0 @@ -@ignore -This file is completely identical to hsuser.texinfo, except that it has the -reference to the programming manual removed. There are definately better ways -to do this! - -This file documents the user interface to the GNU History library. - -Copyright (C) 1988, 1991 Free Software Foundation, Inc. -Authored by Brian Fox. - -Permission is granted to make and distribute verbatim copies of this manual -provided the copyright notice and this permission notice are preserved on -all copies. - -Permission is granted to process this file through Tex and print the -results, provided the printed document carries copying permission notice -identical to this one except for the removal of this paragraph (this -paragraph not being relevant to the printed manual). - -Permission is granted to copy and distribute modified versions of this -manual under the conditions for verbatim copying, provided also that the -GNU Copyright statement is available to the distributee, and provided that -the entire resulting derived work is distributed under the terms of a -permission notice identical to this one. - -Permission is granted to copy and distribute translations of this manual -into another language, under the above conditions for modified versions. -@end ignore - -@node Using History Interactively -@appendix Using History Interactively - -This chapter describes how to use the GNU History Library interactively, -from a user's standpoint. - -@menu -* History Interaction:: What it feels like using History as a user. -@end menu - -@node History Interaction -@section History Interaction -@cindex expansion - -The History library provides a history expansion feature that is similar -to the history expansion in Csh. The following text describes the sytax -that you use to manipulate the history information. - -History expansion takes place in two parts. The first is to determine -which line from the previous history should be used during substitution. -The second is to select portions of that line for inclusion into the -current one. The line selected from the previous history is called the -@dfn{event}, and the portions of that line that are acted upon are -called @dfn{words}. The line is broken into words in the same fashion -that the Bash shell does, so that several English (or Unix) words -surrounded by quotes are considered as one word. - -@menu -* Event Designators:: How to specify which history line to use. -* Word Designators:: Specifying which words are of interest. -* Modifiers:: Modifying the results of susbstitution. -@end menu - -@node Event Designators -@subsection Event Designators -@cindex event designators - -An event designator is a reference to a command line entry in the -history list. - -@table @asis - -@item @code{!} -Start a history subsititution, except when followed by a space, tab, or -the end of the line... @key{=} or @key{(}. - -@item @code{!!} -Refer to the previous command. This is a synonym for @code{!-1}. - -@item @code{!n} -Refer to command line @var{n}. - -@item @code{!-n} -Refer to the command line @var{n} lines back. - -@item @code{!string} -Refer to the most recent command starting with @var{string}. - -@item @code{!?string}[@code{?}] -Refer to the most recent command containing @var{string}. - -@end table - -@node Word Designators -@subsection Word Designators - -A @key{:} separates the event specification from the word designator. It -can be omitted if the word designator begins with a @key{^}, @key{$}, -@key{*} or @key{%}. Words are numbered from the beginning of the line, -with the first word being denoted by a 0 (zero). - -@table @code - -@item 0 (zero) -The zero'th word. For many applications, this is the command word. - -@item n -The @var{n}'th word. - -@item ^ -The first argument. that is, word 1. - -@item $ -The last argument. - -@item % -The word matched by the most recent @code{?string?} search. - -@item x-y -A range of words; @code{-@var{y}} Abbreviates @code{0-@var{y}}. - -@item * -All of the words, excepting the zero'th. This is a synonym for @code{1-$}. -It is not an error to use @key{*} if there is just one word in the event. -The empty string is returned in that case. - -@end table - -@node Modifiers -@subsection Modifiers - -After the optional word designator, you can add a sequence of one or more -of the following modifiers, each preceded by a @key{:}. - -@table @code - -@item # -The entire command line typed so far. This means the current command, -not the previous command, so it really isn't a word designator, and doesn't -belong in this section. - -@item h -Remove a trailing pathname component, leaving only the head. - -@item r -Remove a trailing suffix of the form @samp{.}@var{suffix}, leaving the basename. - -@item e -Remove all but the suffix. - -@item t -Remove all leading pathname components, leaving the tail. - -@item p -Print the new command but do not execute it. -@end table diff --git a/gnu/usr.bin/gdb/doc/remote.texi b/gnu/usr.bin/gdb/doc/remote.texi deleted file mode 100644 index 422379d..0000000 --- a/gnu/usr.bin/gdb/doc/remote.texi +++ /dev/null @@ -1,1424 +0,0 @@ -@c -*- Texinfo -*- -@c Copyright (c) 1990 1991 1992 1993 Free Software Foundation, Inc. -@c This file is part of the source for the GDB manual. -@c This text diverted to "Remote Debugging" section in general case; -@c however, if we're doing a manual specifically for one of these, it -@c belongs up front (in "Getting In and Out" chapter). - -@ifset REMOTESTUB -@node Remote Serial -@subsection The @value{GDBN} remote serial protocol - -@cindex remote serial debugging, overview -To debug a program running on another machine (the debugging -@dfn{target} machine), you must first arrange for all the usual -prerequisites for the program to run by itself. For example, for a C -program, you need - -@enumerate -@item -A startup routine to set up the C runtime environment; these usually -have a name like @file{crt0}. The startup routine may be supplied by -your hardware supplier, or you may have to write your own. - -@item -You probably need a C subroutine library to support your program's -subroutine calls, notably managing input and output. - -@item -A way of getting your program to the other machine---for example, a -download program. These are often supplied by the hardware -manufacturer, but you may have to write your own from hardware -documentation. -@end enumerate - -The next step is to arrange for your program to use a serial port to -communicate with the machine where @value{GDBN} is running (the @dfn{host} -machine). In general terms, the scheme looks like this: - -@table @emph -@item On the host, -@value{GDBN} already understands how to use this protocol; when everything -else is set up, you can simply use the @samp{target remote} command -(@pxref{Targets,,Specifying a Debugging Target}). - -@item On the target, -you must link with your program a few special-purpose subroutines that -implement the @value{GDBN} remote serial protocol. The file containing these -subroutines is called a @dfn{debugging stub}. - -@ifset GDBSERVER -On certain remote targets, you can use an auxiliary program -@code{gdbserver} instead of linking a stub into your program. -@xref{Server,,Using the @code{gdbserver} program}, for details. -@end ifset -@end table - -The debugging stub is specific to the architecture of the remote -machine; for example, use @file{sparc-stub.c} to debug programs on -@sc{sparc} boards. - -@cindex remote serial stub list -These working remote stubs are distributed with @value{GDBN}: - -@table @code -@item sparc-stub.c -@kindex sparc-stub.c -For @sc{sparc} architectures. - -@item m68k-stub.c -@kindex m68k-stub.c -@cindex Motorola 680x0 -@cindex m680x0 -For Motorola 680x0 architectures. - -@item i386-stub.c -@kindex i386-stub.c -@cindex Intel -@cindex i386 -For Intel 386 and compatible architectures. -@end table - -The @file{README} file in the @value{GDBN} distribution may list other -recently added stubs. - -@menu -* Stub Contents:: What the stub can do for you -* Bootstrapping:: What you must do for the stub -* Debug Session:: Putting it all together -* Protocol:: Outline of the communication protocol -@ifset GDBSERVER -* Server:: Using the `gdbserver' program -@end ifset -@end menu - -@node Stub Contents -@subsubsection What the stub can do for you - -@cindex remote serial stub -The debugging stub for your architecture supplies these three -subroutines: - -@table @code -@item set_debug_traps -@kindex set_debug_traps -@cindex remote serial stub, initialization -This routine arranges for @code{handle_exception} to run when your -program stops. You must call this subroutine explicitly near the -beginning of your program. - -@item handle_exception -@kindex handle_exception -@cindex remote serial stub, main routine -This is the central workhorse, but your program never calls it -explicitly---the setup code arranges for @code{handle_exception} to -run when a trap is triggered. - -@code{handle_exception} takes control when your program stops during -execution (for example, on a breakpoint), and mediates communications -with @value{GDBN} on the host machine. This is where the communications -protocol is implemented; @code{handle_exception} acts as the @value{GDBN} -representative on the target machine; it begins by sending summary -information on the state of your program, then continues to execute, -retrieving and transmitting any information @value{GDBN} needs, until you -execute a @value{GDBN} command that makes your program resume; at that point, -@code{handle_exception} returns control to your own code on the target -machine. - -@item breakpoint -@cindex @code{breakpoint} subroutine, remote -Use this auxiliary subroutine to make your program contain a -breakpoint. Depending on the particular situation, this may be the only -way for @value{GDBN} to get control. For instance, if your target -machine has some sort of interrupt button, you won't need to call this; -pressing the interrupt button transfers control to -@code{handle_exception}---in effect, to @value{GDBN}. On some machines, -simply receiving characters on the serial port may also trigger a trap; -again, in that situation, you don't need to call @code{breakpoint} from -your own program---simply running @samp{target remote} from the host -@value{GDBN} session gets control. - -Call @code{breakpoint} if none of these is true, or if you simply want -to make certain your program stops at a predetermined point for the -start of your debugging session. -@end table - -@node Bootstrapping -@subsubsection What you must do for the stub - -@cindex remote stub, support routines -The debugging stubs that come with @value{GDBN} are set up for a particular -chip architecture, but they have no information about the rest of your -debugging target machine. - -First of all you need to tell the stub how to communicate with the -serial port. - -@table @code -@item int getDebugChar() -@kindex getDebugChar -Write this subroutine to read a single character from the serial port. -It may be identical to @code{getchar} for your target system; a -different name is used to allow you to distinguish the two if you wish. - -@item void putDebugChar(int) -@kindex putDebugChar -Write this subroutine to write a single character to the serial port. -It may be identical to @code{putchar} for your target system; a -different name is used to allow you to distinguish the two if you wish. -@end table - -@cindex control C, and remote debugging -@cindex interrupting remote targets -If you want @value{GDBN} to be able to stop your program while it is -running, you need to use an interrupt-driven serial driver, and arrange -for it to stop when it receives a @code{^C} (@samp{\003}, the control-C -character). That is the character which @value{GDBN} uses to tell the -remote system to stop. - -Getting the debugging target to return the proper status to @value{GDBN} -probably requires changes to the standard stub; one quick and dirty way -is to just execute a breakpoint instruction (the ``dirty'' part is that -@value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}). - -Other routines you need to supply are: - -@table @code -@item void exceptionHandler (int @var{exception_number}, void *@var{exception_address}) -@kindex exceptionHandler -Write this function to install @var{exception_address} in the exception -handling tables. You need to do this because the stub does not have any -way of knowing what the exception handling tables on your target system -are like (for example, the processor's table might be in @sc{rom}, -containing entries which point to a table in @sc{ram}). -@var{exception_number} is the exception number which should be changed; -its meaning is architecture-dependent (for example, different numbers -might represent divide by zero, misaligned access, etc). When this -exception occurs, control should be transferred directly to -@var{exception_address}, and the processor state (stack, registers, -and so on) should be just as it is when a processor exception occurs. So if -you want to use a jump instruction to reach @var{exception_address}, it -should be a simple jump, not a jump to subroutine. - -For the 386, @var{exception_address} should be installed as an interrupt -gate so that interrupts are masked while the handler runs. The gate -should be at privilege level 0 (the most privileged level). The -@sc{sparc} and 68k stubs are able to mask interrupts themself without -help from @code{exceptionHandler}. - -@item void flush_i_cache() -@kindex flush_i_cache -Write this subroutine to flush the instruction cache, if any, on your -target machine. If there is no instruction cache, this subroutine may -be a no-op. - -On target machines that have instruction caches, @value{GDBN} requires this -function to make certain that the state of your program is stable. -@end table - -@noindent -You must also make sure this library routine is available: - -@table @code -@item void *memset(void *, int, int) -@kindex memset -This is the standard library function @code{memset} that sets an area of -memory to a known value. If you have one of the free versions of -@code{libc.a}, @code{memset} can be found there; otherwise, you must -either obtain it from your hardware manufacturer, or write your own. -@end table - -If you do not use the GNU C compiler, you may need other standard -library subroutines as well; this varies from one stub to another, -but in general the stubs are likely to use any of the common library -subroutines which @code{gcc} generates as inline code. - - -@node Debug Session -@subsubsection Putting it all together - -@cindex remote serial debugging summary -In summary, when your program is ready to debug, you must follow these -steps. - -@enumerate -@item -Make sure you have the supporting low-level routines -(@pxref{Bootstrapping,,What you must do for the stub}): -@display -@code{getDebugChar}, @code{putDebugChar}, -@code{flush_i_cache}, @code{memset}, @code{exceptionHandler}. -@end display - -@item -Insert these lines near the top of your program: - -@example -set_debug_traps(); -breakpoint(); -@end example - -@item -For the 680x0 stub only, you need to provide a variable called -@code{exceptionHook}. Normally you just use - -@example -void (*exceptionHook)() = 0; -@end example - -but if before calling @code{set_debug_traps}, you set it to point to a -function in your program, that function is called when -@code{@value{GDBN}} continues after stopping on a trap (for example, bus -error). The function indicated by @code{exceptionHook} is called with -one parameter: an @code{int} which is the exception number. - -@item -Compile and link together: your program, the @value{GDBN} debugging stub for -your target architecture, and the supporting subroutines. - -@item -Make sure you have a serial connection between your target machine and -the @value{GDBN} host, and identify the serial port used for this on the host. - -@item -@c The "remote" target now provides a `load' command, so we should -@c document that. FIXME. -Download your program to your target machine (or get it there by -whatever means the manufacturer provides), and start it. - -@item -To start remote debugging, run @value{GDBN} on the host machine, and specify -as an executable file the program that is running in the remote machine. -This tells @value{GDBN} how to find your program's symbols and the contents -of its pure text. - -@cindex serial line, @code{target remote} -Then establish communication using the @code{target remote} command. -Its argument specifies how to communicate with the target -machine---either via a devicename attached to a direct serial line, or a -TCP port (usually to a terminal server which in turn has a serial line -to the target). For example, to use a serial line connected to the -device named @file{/dev/ttyb}: - -@example -target remote /dev/ttyb -@end example - -@cindex TCP port, @code{target remote} -To use a TCP connection, use an argument of the form -@code{@var{host}:port}. For example, to connect to port 2828 on a -terminal server named @code{manyfarms}: - -@example -target remote manyfarms:2828 -@end example -@end enumerate - -Now you can use all the usual commands to examine and change data and to -step and continue the remote program. - -To resume the remote program and stop debugging it, use the @code{detach} -command. - -@cindex interrupting remote programs -@cindex remote programs, interrupting -Whenever @value{GDBN} is waiting for the remote program, if you type the -interrupt character (often @key{C-C}), @value{GDBN} attempts to stop the -program. This may or may not succeed, depending in part on the hardware -and the serial drivers the remote system uses. If you type the -interrupt character once again, @value{GDBN} displays this prompt: - -@example -Interrupted while waiting for the program. -Give up (and stop debugging it)? (y or n) -@end example - -If you type @kbd{y}, @value{GDBN} abandons the remote debugging session. -(If you decide you want to try again later, you can use @samp{target -remote} again to connect once more.) If you type @kbd{n}, @value{GDBN} -goes back to waiting. - -@node Protocol -@subsubsection Communication protocol - -@cindex debugging stub, example -@cindex remote stub, example -@cindex stub example, remote debugging -The stub files provided with @value{GDBN} implement the target side of the -communication protocol, and the @value{GDBN} side is implemented in the -@value{GDBN} source file @file{remote.c}. Normally, you can simply allow -these subroutines to communicate, and ignore the details. (If you're -implementing your own stub file, you can still ignore the details: start -with one of the existing stub files. @file{sparc-stub.c} is the best -organized, and therefore the easiest to read.) - -However, there may be occasions when you need to know something about -the protocol---for example, if there is only one serial port to your -target machine, you might want your program to do something special if -it recognizes a packet meant for @value{GDBN}. - -@cindex protocol, @value{GDBN} remote serial -@cindex serial protocol, @value{GDBN} remote -@cindex remote serial protocol -All @value{GDBN} commands and responses (other than acknowledgements, which -are single characters) are sent as a packet which includes a -checksum. A packet is introduced with the character @samp{$}, and ends -with the character @samp{#} followed by a two-digit checksum: - -@example -$@var{packet info}#@var{checksum} -@end example - -@cindex checksum, for @value{GDBN} remote -@noindent -@var{checksum} is computed as the modulo 256 sum of the @var{packet -info} characters. - -When either the host or the target machine receives a packet, the first -response expected is an acknowledgement: a single character, either -@samp{+} (to indicate the package was received correctly) or @samp{-} -(to request retransmission). - -The host (@value{GDBN}) sends commands, and the target (the debugging stub -incorporated in your program) sends data in response. The target also -sends data when your program stops. - -Command packets are distinguished by their first character, which -identifies the kind of command. - -These are the commands currently supported: - -@table @code -@item g -Requests the values of CPU registers. - -@item G -Sets the values of CPU registers. - -@item m@var{addr},@var{count} -Read @var{count} bytes at location @var{addr}. - -@item M@var{addr},@var{count}:@dots{} -Write @var{count} bytes at location @var{addr}. - -@need 500 -@item c -@itemx c@var{addr} -Resume execution at the current address (or at @var{addr} if supplied). - -@need 500 -@item s -@itemx s@var{addr} -Step the target program for one instruction, from either the current -program counter or from @var{addr} if supplied. - -@item k -Kill the target program. - -@item ? -Report the most recent signal. To allow you to take advantage of the -@value{GDBN} signal handling commands, one of the functions of the debugging -stub is to report CPU traps as the corresponding POSIX signal values. -@end table - -@kindex set remotedebug -@kindex show remotedebug -@cindex packets, reporting on stdout -@cindex serial connections, debugging -If you have trouble with the serial connection, you can use the command -@code{set remotedebug}. This makes @value{GDBN} report on all packets sent -back and forth across the serial line to the remote machine. The -packet-debugging information is printed on the @value{GDBN} standard output -stream. @code{set remotedebug off} turns it off, and @code{show -remotedebug} shows you its current state. - -@ifset GDBSERVER -@node Server -@subsubsection Using the @code{gdbserver} program - -@kindex gdbserver -@cindex remote connection without stubs -@code{gdbserver} is a control program for Unix-like systems, which -allows you to connect your program with a remote @value{GDBN} via -@code{target remote}---but without linking in the usual debugging stub. - -@code{gdbserver} is not a complete replacement for the debugging stubs, -because it requires essentially the same operating-system facilities -that @value{GDBN} itself does. In fact, a system that can run -@code{gdbserver} to connect to a remote @value{GDBN} could also run -@value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless, -because it is a much smaller program than @value{GDBN} itself. It is -also easier to port than all of @value{GDBN}, so you may be able to get -started more quickly on a new system by using @code{gdbserver}. -Finally, if you develop code for real-time systems, you may find that -the tradeoffs involved in real-time operation make it more convenient to -do as much development work as possible on another system, for example -by cross-compiling. You can use @code{gdbserver} to make a similar -choice for debugging. - -@value{GDBN} and @code{gdbserver} communicate via either a serial line -or a TCP connection, using the standard @value{GDBN} remote serial -protocol. - -@table @emph -@item On the target machine, -you need to have a copy of the program you want to debug. -@code{gdbserver} does not need your program's symbol table, so you can -strip the program if necessary to save space. @value{GDBN} on the host -system does all the symbol handling. - -To use the server, you must tell it how to communicate with @value{GDBN}; -the name of your program; and the arguments for your program. The -syntax is: - -@smallexample -target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ] -@end smallexample - -@var{comm} is either a device name (to use a serial line) or a TCP -hostname and portnumber. For example, to debug Emacs with the argument -@samp{foo.txt} and communicate with @value{GDBN} over the serial port -@file{/dev/com1}: - -@smallexample -target> gdbserver /dev/com1 emacs foo.txt -@end smallexample - -@code{gdbserver} waits passively for the host @value{GDBN} to communicate -with it. - -To use a TCP connection instead of a serial line: - -@smallexample -target> gdbserver host:2345 emacs foo.txt -@end smallexample - -The only difference from the previous example is the first argument, -specifying that you are communicating with the host @value{GDBN} via -TCP. The @samp{host:2345} argument means that @code{gdbserver} is to -expect a TCP connection from machine @samp{host} to local TCP port 2345. -(Currently, the @samp{host} part is ignored.) You can choose any number -you want for the port number as long as it does not conflict with any -TCP ports already in use on the target system (for example, @code{23} is -reserved for @code{telnet}).@footnote{If you choose a port number that -conflicts with another service, @code{gdbserver} prints an error message -and exits.} You must use the same port number with the host @value{GDBN} -@code{target remote} command. - -@item On the @value{GDBN} host machine, -you need an unstripped copy of your program, since @value{GDBN} needs -symbols and debugging information. Start up @value{GDBN} as usual, -using the name of the local copy of your program as the first argument. -(You may also need the @w{@samp{--baud}} option if the serial line is -running at anything other than 9600 bps.) After that, use @code{target -remote} to establish communications with @code{gdbserver}. Its argument -is either a device name (usually a serial device, like -@file{/dev/ttyb}), or a TCP port descriptor in the form -@code{@var{host}:@var{PORT}}. For example: - -@smallexample -(@value{GDBP}) target remote /dev/ttyb -@end smallexample - -@noindent -communicates with the server via serial line @file{/dev/ttyb}, and - -@smallexample -(@value{GDBP}) target remote the-target:2345 -@end smallexample - -@noindent -communicates via a TCP connection to port 2345 on host @w{@file{the-target}}. -For TCP connections, you must start up @code{gdbserver} prior to using -the @code{target remote} command. Otherwise you may get an error whose -text depends on the host system, but which usually looks something like -@samp{Connection refused}. -@end table -@end ifset - -@end ifset - -@ifset I960 -@node i960-Nindy Remote -@subsection @value{GDBN} with a remote i960 (Nindy) - -@cindex Nindy -@cindex i960 -@dfn{Nindy} is a ROM Monitor program for Intel 960 target systems. When -@value{GDBN} is configured to control a remote Intel 960 using Nindy, you can -tell @value{GDBN} how to connect to the 960 in several ways: - -@itemize @bullet -@item -Through command line options specifying serial port, version of the -Nindy protocol, and communications speed; - -@item -By responding to a prompt on startup; - -@item -By using the @code{target} command at any point during your @value{GDBN} -session. @xref{Target Commands, ,Commands for managing targets}. - -@end itemize - -@menu -* Nindy Startup:: Startup with Nindy -* Nindy Options:: Options for Nindy -* Nindy Reset:: Nindy reset command -@end menu - -@node Nindy Startup -@subsubsection Startup with Nindy - -If you simply start @code{@value{GDBP}} without using any command-line -options, you are prompted for what serial port to use, @emph{before} you -reach the ordinary @value{GDBN} prompt: - -@example -Attach /dev/ttyNN -- specify NN, or "quit" to quit: -@end example - -@noindent -Respond to the prompt with whatever suffix (after @samp{/dev/tty}) -identifies the serial port you want to use. You can, if you choose, -simply start up with no Nindy connection by responding to the prompt -with an empty line. If you do this and later wish to attach to Nindy, -use @code{target} (@pxref{Target Commands, ,Commands for managing targets}). - -@node Nindy Options -@subsubsection Options for Nindy - -These are the startup options for beginning your @value{GDBN} session with a -Nindy-960 board attached: - -@table @code -@item -r @var{port} -Specify the serial port name of a serial interface to be used to connect -to the target system. This option is only available when @value{GDBN} is -configured for the Intel 960 target architecture. You may specify -@var{port} as any of: a full pathname (e.g. @samp{-r /dev/ttya}), a -device name in @file{/dev} (e.g. @samp{-r ttya}), or simply the unique -suffix for a specific @code{tty} (e.g. @samp{-r a}). - -@item -O -(An uppercase letter ``O'', not a zero.) Specify that @value{GDBN} should use -the ``old'' Nindy monitor protocol to connect to the target system. -This option is only available when @value{GDBN} is configured for the Intel 960 -target architecture. - -@quotation -@emph{Warning:} if you specify @samp{-O}, but are actually trying to -connect to a target system that expects the newer protocol, the connection -fails, appearing to be a speed mismatch. @value{GDBN} repeatedly -attempts to reconnect at several different line speeds. You can abort -this process with an interrupt. -@end quotation - -@item -brk -Specify that @value{GDBN} should first send a @code{BREAK} signal to the target -system, in an attempt to reset it, before connecting to a Nindy target. - -@quotation -@emph{Warning:} Many target systems do not have the hardware that this -requires; it only works with a few boards. -@end quotation -@end table - -The standard @samp{-b} option controls the line speed used on the serial -port. - -@c @group -@node Nindy Reset -@subsubsection Nindy reset command - -@table @code -@item reset -@kindex reset -For a Nindy target, this command sends a ``break'' to the remote target -system; this is only useful if the target has been equipped with a -circuit to perform a hard reset (or some other interesting action) when -a break is detected. -@end table -@c @end group -@end ifset - -@ifset AMD29K -@node UDI29K Remote -@subsection The UDI protocol for AMD29K - -@cindex UDI -@cindex AMD29K via UDI -@value{GDBN} supports AMD's UDI (``Universal Debugger Interface'') -protocol for debugging the a29k processor family. To use this -configuration with AMD targets running the MiniMON monitor, you need the -program @code{MONTIP}, available from AMD at no charge. You can also -use @value{GDBN} with the UDI conformant a29k simulator program -@code{ISSTIP}, also available from AMD. - -@table @code -@item target udi @var{keyword} -@kindex udi -Select the UDI interface to a remote a29k board or simulator, where -@var{keyword} is an entry in the AMD configuration file @file{udi_soc}. -This file contains keyword entries which specify parameters used to -connect to a29k targets. If the @file{udi_soc} file is not in your -working directory, you must set the environment variable @samp{UDICONF} -to its pathname. -@end table - -@node EB29K Remote -@subsection The EBMON protocol for AMD29K - -@cindex EB29K board -@cindex running 29K programs - -AMD distributes a 29K development board meant to fit in a PC, together -with a DOS-hosted monitor program called @code{EBMON}. As a shorthand -term, this development system is called the ``EB29K''. To use -@value{GDBN} from a Unix system to run programs on the EB29K board, you -must first connect a serial cable between the PC (which hosts the EB29K -board) and a serial port on the Unix system. In the following, we -assume you've hooked the cable between the PC's @file{COM1} port and -@file{/dev/ttya} on the Unix system. - -@menu -* Comms (EB29K):: Communications setup -* gdb-EB29K:: EB29K cross-debugging -* Remote Log:: Remote log -@end menu - -@node Comms (EB29K) -@subsubsection Communications setup - -The next step is to set up the PC's port, by doing something like this -in DOS on the PC: - -@example -C:\> MODE com1:9600,n,8,1,none -@end example - -@noindent -This example---run on an MS DOS 4.0 system---sets the PC port to 9600 -bps, no parity, eight data bits, one stop bit, and no ``retry'' action; -you must match the communications parameters when establishing the Unix -end of the connection as well. -@c FIXME: Who knows what this "no retry action" crud from the DOS manual may -@c mean? It's optional; leave it out? ---pesch@cygnus.com, 25feb91 - -To give control of the PC to the Unix side of the serial line, type -the following at the DOS console: - -@example -C:\> CTTY com1 -@end example - -@noindent -(Later, if you wish to return control to the DOS console, you can use -the command @code{CTTY con}---but you must send it over the device that -had control, in our example over the @file{COM1} serial line). - -From the Unix host, use a communications program such as @code{tip} or -@code{cu} to communicate with the PC; for example, - -@example -cu -s 9600 -l /dev/ttya -@end example - -@noindent -The @code{cu} options shown specify, respectively, the linespeed and the -serial port to use. If you use @code{tip} instead, your command line -may look something like the following: - -@example -tip -9600 /dev/ttya -@end example - -@noindent -Your system may require a different name where we show -@file{/dev/ttya} as the argument to @code{tip}. The communications -parameters, including which port to use, are associated with the -@code{tip} argument in the ``remote'' descriptions file---normally the -system table @file{/etc/remote}. -@c FIXME: What if anything needs doing to match the "n,8,1,none" part of -@c the DOS side's comms setup? cu can support -o (odd -@c parity), -e (even parity)---apparently no settings for no parity or -@c for character size. Taken from stty maybe...? John points out tip -@c can set these as internal variables, eg ~s parity=none; man stty -@c suggests that it *might* work to stty these options with stdin or -@c stdout redirected... ---pesch@cygnus.com, 25feb91 - -@kindex EBMON -Using the @code{tip} or @code{cu} connection, change the DOS working -directory to the directory containing a copy of your 29K program, then -start the PC program @code{EBMON} (an EB29K control program supplied -with your board by AMD). You should see an initial display from -@code{EBMON} similar to the one that follows, ending with the -@code{EBMON} prompt @samp{#}--- - -@example -C:\> G: - -G:\> CD \usr\joe\work29k - -G:\USR\JOE\WORK29K> EBMON -Am29000 PC Coprocessor Board Monitor, version 3.0-18 -Copyright 1990 Advanced Micro Devices, Inc. -Written by Gibbons and Associates, Inc. - -Enter '?' or 'H' for help - -PC Coprocessor Type = EB29K -I/O Base = 0x208 -Memory Base = 0xd0000 - -Data Memory Size = 2048KB -Available I-RAM Range = 0x8000 to 0x1fffff -Available D-RAM Range = 0x80002000 to 0x801fffff - -PageSize = 0x400 -Register Stack Size = 0x800 -Memory Stack Size = 0x1800 - -CPU PRL = 0x3 -Am29027 Available = No -Byte Write Available = Yes - -# ~. -@end example - -Then exit the @code{cu} or @code{tip} program (done in the example by -typing @code{~.} at the @code{EBMON} prompt). @code{EBMON} keeps -running, ready for @value{GDBN} to take over. - -For this example, we've assumed what is probably the most convenient -way to make sure the same 29K program is on both the PC and the Unix -system: a PC/NFS connection that establishes ``drive @code{G:}'' on the -PC as a file system on the Unix host. If you do not have PC/NFS or -something similar connecting the two systems, you must arrange some -other way---perhaps floppy-disk transfer---of getting the 29K program -from the Unix system to the PC; @value{GDBN} does @emph{not} download it over the -serial line. - -@node gdb-EB29K -@subsubsection EB29K cross-debugging - -Finally, @code{cd} to the directory containing an image of your 29K -program on the Unix system, and start @value{GDBN}---specifying as argument the -name of your 29K program: - -@example -cd /usr/joe/work29k -@value{GDBP} myfoo -@end example - -@need 500 -Now you can use the @code{target} command: - -@example -target amd-eb /dev/ttya 9600 MYFOO -@c FIXME: test above 'target amd-eb' as spelled, with caps! caps are meant to -@c emphasize that this is the name as seen by DOS (since I think DOS is -@c single-minded about case of letters). ---pesch@cygnus.com, 25feb91 -@end example - -@noindent -In this example, we've assumed your program is in a file called -@file{myfoo}. Note that the filename given as the last argument to -@code{target amd-eb} should be the name of the program as it appears to DOS. -In our example this is simply @code{MYFOO}, but in general it can include -a DOS path, and depending on your transfer mechanism may not resemble -the name on the Unix side. - -At this point, you can set any breakpoints you wish; when you are ready -to see your program run on the 29K board, use the @value{GDBN} command -@code{run}. - -To stop debugging the remote program, use the @value{GDBN} @code{detach} -command. - -To return control of the PC to its console, use @code{tip} or @code{cu} -once again, after your @value{GDBN} session has concluded, to attach to -@code{EBMON}. You can then type the command @code{q} to shut down -@code{EBMON}, returning control to the DOS command-line interpreter. -Type @code{CTTY con} to return command input to the main DOS console, -and type @kbd{~.} to leave @code{tip} or @code{cu}. - -@node Remote Log -@subsubsection Remote log -@kindex eb.log -@cindex log file for EB29K - -The @code{target amd-eb} command creates a file @file{eb.log} in the -current working directory, to help debug problems with the connection. -@file{eb.log} records all the output from @code{EBMON}, including echoes -of the commands sent to it. Running @samp{tail -f} on this file in -another window often helps to understand trouble with @code{EBMON}, or -unexpected events on the PC side of the connection. - -@end ifset - -@ifset ST2000 -@node ST2000 Remote -@subsection @value{GDBN} with a Tandem ST2000 - -To connect your ST2000 to the host system, see the manufacturer's -manual. Once the ST2000 is physically attached, you can run - -@example -target st2000 @var{dev} @var{speed} -@end example - -@noindent -to establish it as your debugging environment. @var{dev} is normally -the name of a serial device, such as @file{/dev/ttya}, connected to the -ST2000 via a serial line. You can instead specify @var{dev} as a TCP -connection (for example, to a serial line attached via a terminal -concentrator) using the syntax @code{@var{hostname}:@var{portnumber}}. - -The @code{load} and @code{attach} commands are @emph{not} defined for -this target; you must load your program into the ST2000 as you normally -would for standalone operation. @value{GDBN} reads debugging information -(such as symbols) from a separate, debugging version of the program -available on your host computer. -@c FIXME!! This is terribly vague; what little content is here is -@c basically hearsay. - -@cindex ST2000 auxiliary commands -These auxiliary @value{GDBN} commands are available to help you with the ST2000 -environment: - -@table @code -@item st2000 @var{command} -@kindex st2000 @var{cmd} -@cindex STDBUG commands (ST2000) -@cindex commands to STDBUG (ST2000) -Send a @var{command} to the STDBUG monitor. See the manufacturer's -manual for available commands. - -@item connect -@cindex connect (to STDBUG) -Connect the controlling terminal to the STDBUG command monitor. When -you are done interacting with STDBUG, typing either of two character -sequences gets you back to the @value{GDBN} command prompt: -@kbd{@key{RET}~.} (Return, followed by tilde and period) or -@kbd{@key{RET}~@key{C-d}} (Return, followed by tilde and control-D). -@end table -@end ifset - -@ifset VXWORKS -@node VxWorks Remote -@subsection @value{GDBN} and VxWorks -@cindex VxWorks - -@value{GDBN} enables developers to spawn and debug tasks running on networked -VxWorks targets from a Unix host. Already-running tasks spawned from -the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on -both the Unix host and on the VxWorks target. The program -@code{gdb} is installed and executed on the Unix host. (It may be -installed with the name @code{vxgdb}, to distinguish it from a -@value{GDBN} for debugging programs on the host itself.) - -The following information on connecting to VxWorks was current when -this manual was produced; newer releases of VxWorks may use revised -procedures. - -@kindex INCLUDE_RDB -To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel -to include the remote debugging interface routines in the VxWorks -library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the -VxWorks configuration file @file{configAll.h} and rebuild your VxWorks -kernel. The resulting kernel contains @file{rdb.a}, and spawns the -source debugging task @code{tRdbTask} when VxWorks is booted. For more -information on configuring and remaking VxWorks, see the manufacturer's -manual. -@c VxWorks, see the @cite{VxWorks Programmer's Guide}. - -Once you have included @file{rdb.a} in your VxWorks system image and set -your Unix execution search path to find @value{GDBN}, you are ready to -run @value{GDBN}. From your Unix host, run @code{gdb} (or @code{vxgdb}, -depending on your installation). - -@value{GDBN} comes up showing the prompt: - -@example -(vxgdb) -@end example - -@menu -* VxWorks Connection:: Connecting to VxWorks -* VxWorks Download:: VxWorks download -* VxWorks Attach:: Running tasks -@end menu - -@node VxWorks Connection -@subsubsection Connecting to VxWorks - -The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the -network. To connect to a target whose host name is ``@code{tt}'', type: - -@example -(vxgdb) target vxworks tt -@end example - -@need 750 -@value{GDBN} displays messages like these: - -@smallexample -Attaching remote machine across net... -Connected to tt. -@end smallexample - -@need 1000 -@value{GDBN} then attempts to read the symbol tables of any object modules -loaded into the VxWorks target since it was last booted. @value{GDBN} locates -these files by searching the directories listed in the command search -path (@pxref{Environment, ,Your program's environment}); if it fails -to find an object file, it displays a message such as: - -@example -prog.o: No such file or directory. -@end example - -When this happens, add the appropriate directory to the search path with -the @value{GDBN} command @code{path}, and execute the @code{target} -command again. - -@node VxWorks Download -@subsubsection VxWorks download - -@cindex download to VxWorks -If you have connected to the VxWorks target and you want to debug an -object that has not yet been loaded, you can use the @value{GDBN} -@code{load} command to download a file from Unix to VxWorks -incrementally. The object file given as an argument to the @code{load} -command is actually opened twice: first by the VxWorks target in order -to download the code, then by @value{GDBN} in order to read the symbol -table. This can lead to problems if the current working directories on -the two systems differ. If both systems have NFS mounted the same -filesystems, you can avoid these problems by using absolute paths. -Otherwise, it is simplest to set the working directory on both systems -to the directory in which the object file resides, and then to reference -the file by its name, without any path. For instance, a program -@file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks -and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this -program, type this on VxWorks: - -@example --> cd "@var{vxpath}/vw/demo/rdb" -@end example - -Then, in @value{GDBN}, type: - -@example -(vxgdb) cd @var{hostpath}/vw/demo/rdb -(vxgdb) load prog.o -@end example - -@value{GDBN} displays a response similar to this: - -@smallexample -Reading symbol data from wherever/vw/demo/rdb/prog.o... done. -@end smallexample - -You can also use the @code{load} command to reload an object module -after editing and recompiling the corresponding source file. Note that -this makes @value{GDBN} delete all currently-defined breakpoints, -auto-displays, and convenience variables, and to clear the value -history. (This is necessary in order to preserve the integrity of -debugger data structures that reference the target system's symbol -table.) - -@node VxWorks Attach -@subsubsection Running tasks - -@cindex running VxWorks tasks -You can also attach to an existing task using the @code{attach} command as -follows: - -@example -(vxgdb) attach @var{task} -@end example - -@noindent -where @var{task} is the VxWorks hexadecimal task ID. The task can be running -or suspended when you attach to it. Running tasks are suspended at -the time of attachment. -@end ifset - -@ifset H8 -@node Hitachi Remote -@subsection @value{GDBN} and Hitachi microprocessors -@value{GDBN} needs to know these things to talk to your -Hitachi SH, H8/300, or H8/500: - -@enumerate -@item -that you want to use @samp{target hms}, the remote debugging interface -for Hitachi microprocessors, or @samp{target e7000}, the in-circuit -emulator for the Hitachi SH and the Hitachi 300H. (@samp{target hms} is -the default when GDB is configured specifically for the Hitachi SH, -H8/300, or H8/500.) - -@item -what serial device connects your host to your Hitachi board (the first -serial device available on your host is the default). - -@ifclear H8EXCLUSIVE -@c this is only for Unix hosts, not of interest to Hitachi -@item -what speed to use over the serial device. -@end ifclear -@end enumerate - -@menu -* Hitachi Boards:: Connecting to Hitachi boards. -* Hitachi ICE:: Using the E7000 In-Circuit Emulator. -* Hitachi Special:: Special @value{GDBN} commands for Hitachi micros. -@end menu - -@node Hitachi Boards -@subsubsection Connecting to Hitachi boards - -@ifclear H8EXCLUSIVE -@c only for Unix hosts -@kindex device -@cindex serial device, Hitachi micros -Use the special @code{@value{GDBP}} command @samp{device @var{port}} if you -need to explicitly set the serial device. The default @var{port} is the -first available port on your host. This is only necessary on Unix -hosts, where it is typically something like @file{/dev/ttya}. - -@kindex speed -@cindex serial line speed, Hitachi micros -@code{@value{GDBP}} has another special command to set the communications -speed: @samp{speed @var{bps}}. This command also is only used from Unix -hosts; on DOS hosts, set the line speed as usual from outside GDB with -the DOS @kbd{mode} command (for instance, @w{@samp{mode -com2:9600,n,8,1,p}} for a 9600 bps connection). - -The @samp{device} and @samp{speed} commands are available only when you -use a Unix host to debug your Hitachi microprocessor programs. If you -use a DOS host, -@end ifclear -@value{GDBN} depends on an auxiliary terminate-and-stay-resident program -called @code{asynctsr} to communicate with the development board -through a PC serial port. You must also use the DOS @code{mode} command -to set up the serial port on the DOS side. - -@ifset DOSHOST -The following sample session illustrates the steps needed to start a -program under @value{GDBN} control on an H8/300. The example uses a -sample H8/300 program called @file{t.x}. The procedure is the same for -the Hitachi SH and the H8/500. - -First hook up your development board. In this example, we use a -board attached to serial port @code{COM2}; if you use a different serial -port, substitute its name in the argument of the @code{mode} command. -When you call @code{asynctsr}, the auxiliary comms program used by the -degugger, you give it just the numeric part of the serial port's name; -for example, @samp{asyncstr 2} below runs @code{asyncstr} on -@code{COM2}. - -@example -(eg-C:\H8300\TEST) mode com2:9600,n,8,1,p - -Resident portion of MODE loaded - -COM2: 9600, n, 8, 1, p - -(eg-C:\H8300\TEST) asynctsr 2 -@end example - -@quotation -@emph{Warning:} We have noticed a bug in PC-NFS that conflicts with -@code{asynctsr}. If you also run PC-NFS on your DOS host, you may need to -disable it, or even boot without it, to use @code{asynctsr} to control -your development board. -@end quotation - -@kindex target hms -Now that serial communications are set up, and the development board is -connected, you can start up @value{GDBN}. Call @code{@value{GDBP}} with -the name of your program as the argument. @code{@value{GDBP}} prompts -you, as usual, with the prompt @samp{(@value{GDBP})}. Use two special -commands to begin your debugging session: @samp{target hms} to specify -cross-debugging to the Hitachi board, and the @code{load} command to -download your program to the board. @code{load} displays the names of -the program's sections, and a @samp{*} for each 2K of data downloaded. -(If you want to refresh @value{GDBN} data on symbols or on the -executable file without downloading, use the @value{GDBN} commands -@code{file} or @code{symbol-file}. These commands, and @code{load} -itself, are described in @ref{Files,,Commands to specify files}.) - -@smallexample -(eg-C:\H8300\TEST) @value{GDBP} t.x -GDB is free software and you are welcome to distribute copies - of it under certain conditions; type "show copying" to see - the conditions. -There is absolutely no warranty for GDB; type "show warranty" -for details. -GDB @value{GDBVN}, Copyright 1992 Free Software Foundation, Inc... -(gdb) target hms -Connected to remote H8/300 HMS system. -(gdb) load t.x -.text : 0x8000 .. 0xabde *********** -.data : 0xabde .. 0xad30 * -.stack : 0xf000 .. 0xf014 * -@end smallexample - -At this point, you're ready to run or debug your program. From here on, -you can use all the usual @value{GDBN} commands. The @code{break} command -sets breakpoints; the @code{run} command starts your program; -@code{print} or @code{x} display data; the @code{continue} command -resumes execution after stopping at a breakpoint. You can use the -@code{help} command at any time to find out more about @value{GDBN} commands. - -Remember, however, that @emph{operating system} facilities aren't -available on your development board; for example, if your program hangs, -you can't send an interrupt---but you can press the @sc{reset} switch! - -Use the @sc{reset} button on the development board -@itemize @bullet -@item -to interrupt your program (don't use @kbd{ctl-C} on the DOS host---it has -no way to pass an interrupt signal to the development board); and - -@item -to return to the @value{GDBN} command prompt after your program finishes -normally. The communications protocol provides no other way for @value{GDBN} -to detect program completion. -@end itemize - -In either case, @value{GDBN} sees the effect of a @sc{reset} on the -development board as a ``normal exit'' of your program. -@end ifset - -@node Hitachi ICE -@subsubsection Using the E7000 in-circuit emulator - -@kindex target e7000 -You can use the E7000 in-circuit emulator to develop code for either the -Hitachi SH or the H8/300H. Use one of these forms of the @samp{target -e7000} command to connect @value{GDBN} to your E7000: - -@table @code -@item target e7000 @var{port} @var{speed} -Use this form if your E7000 is connected to a serial port. The -@var{port} argument identifies what serial port to use (for example, -@samp{com2}). The third argument is the line speed in bits per second -(for example, @samp{9600}). - -@item target e7000 @var{hostname} -If your E7000 is installed as a host on a TCP/IP network, you can just -specify its hostname; @value{GDBN} uses @code{telnet} to connect. -@end table - -@node Hitachi Special -@subsubsection Special @value{GDBN} commands for Hitachi micros - -Some @value{GDBN} commands are available only on the H8/300 or the -H8/500 configurations: - -@table @code -@kindex set machine -@kindex show machine -@item set machine h8300 -@itemx set machine h8300h -Condition @value{GDBN} for one of the two variants of the H8/300 -architecture with @samp{set machine}. You can use @samp{show machine} -to check which variant is currently in effect. - -@kindex set memory @var{mod} -@cindex memory models, H8/500 -@item set memory @var{mod} -@itemx show memory -Specify which H8/500 memory model (@var{mod}) you are using with -@samp{set memory}; check which memory model is in effect with @samp{show -memory}. The accepted values for @var{mod} are @code{small}, -@code{big}, @code{medium}, and @code{compact}. -@end table - -@end ifset - -@ifset MIPS -@node MIPS Remote -@subsection @value{GDBN} and remote MIPS boards - -@cindex MIPS boards -@value{GDBN} can use the MIPS remote debugging protocol to talk to a -MIPS board attached to a serial line. This is available when -you configure @value{GDBN} with @samp{--target=mips-idt-ecoff}. - -@need 1000 -Use these @value{GDBN} commands to specify the connection to your target board: - -@table @code -@item target mips @var{port} -@kindex target mips @var{port} -To run a program on the board, start up @code{@value{GDBP}} with the -name of your program as the argument. To connect to the board, use the -command @samp{target mips @var{port}}, where @var{port} is the name of -the serial port connected to the board. If the program has not already -been downloaded to the board, you may use the @code{load} command to -download it. You can then use all the usual @value{GDBN} commands. - -For example, this sequence connects to the target board through a serial -port, and loads and runs a program called @var{prog} through the -debugger: - -@example -host$ @value{GDBP} @var{prog} -GDB is free software and @dots{} -(gdb) target mips /dev/ttyb -(gdb) load @var{prog} -(gdb) run -@end example - -@item target mips @var{hostname}:@var{portnumber} -On some @value{GDBN} host configurations, you can specify a TCP -connection (for instance, to a serial line managed by a terminal -concentrator) instead of a serial port, using the syntax -@samp{@var{hostname}:@var{portnumber}}. -@end table - -@noindent -@value{GDBN} also supports these special commands for MIPS targets: - -@table @code -@item set mipsfpu off -@itemx show mipsfpu -@kindex set mipsfpu off -@kindex show mipsfpu -@cindex MIPS remote floating point -@cindex floating point, MIPS remote -If your target board does not support the MIPS floating point -coprocessor, you should use the command @samp{set mipsfpu off} (if you -need this, you may wish to put the command in your @value{GDBINIT} -file). This tells @value{GDBN} how to find the return value of -functions which return floating point values. It also allows -@value{GDBN} to avoid saving the floating point registers when calling -functions on the board. (As usual, you can inquire about the -@code{mipsfpu} variable with @samp{show mipsfpu}.) - -@item set remotedebug @var{n} -@itemx show remotedebug -@kindex set remotedebug -@kindex show remotedebug -@cindex @code{remotedebug}, MIPS protocol -@cindex MIPS @code{remotedebug} protocol -@c FIXME! For this to be useful, you must know something about the MIPS -@c FIXME...protocol. Where is it described? -You can see some debugging information about communications with the board -by setting the @code{remotedebug} variable. If you set it to @code{1} using -@samp{set remotedebug 1}, every packet is displayed. If you set it -to @code{2}, every character is displayed. You can check the current value -at any time with the command @samp{show remotedebug}. - -@item set timeout @var{seconds} -@itemx set retransmit-timeout @var{seconds} -@itemx show timeout -@itemx show retransmit-timeout -@cindex @code{timeout}, MIPS protocol -@cindex @code{retransmit-timeout}, MIPS protocol -@kindex set timeout -@kindex show timeout -@kindex set retransmit-timeout -@kindex show retransmit-timeout -You can control the timeout used while waiting for a packet, in the MIPS -remote protocol, with the @code{set timeout @var{seconds}} command. The -default is 5 seconds. Similarly, you can control the timeout used while -waiting for an acknowledgement of a packet with the @code{set -retransmit-timeout @var{seconds}} command. The default is 3 seconds. -You can inspect both values with @code{show timeout} and @code{show -retransmit-timeout}. (These commands are @emph{only} available when -@value{GDBN} is configured for @samp{--target=mips-idt-ecoff}.) - -The timeout set by @code{set timeout} does not apply when @value{GDBN} -is waiting for your program to stop. In that case, @value{GDBN} waits -forever because it has no way of knowing how long the program is going -to run before stopping. -@end table -@end ifset - -@ifset SIMS -@node Simulator -@subsection Simulated CPU target - -@ifset GENERIC -@cindex simulator -@cindex simulator, Z8000 -@cindex Z8000 simulator -@cindex simulator, H8/300 or H8/500 -@cindex H8/300 or H8/500 simulator -@cindex simulator, Hitachi SH -@cindex Hitachi SH simulator -@cindex CPU simulator -For some configurations, @value{GDBN} includes a CPU simulator that you -can use instead of a hardware CPU to debug your programs. Currently, -a simulator is available when @value{GDBN} is configured to debug Zilog -Z8000 or Hitachi microprocessor targets. -@end ifset - -@ifclear GENERIC -@ifset H8 -@cindex simulator, H8/300 or H8/500 -@cindex Hitachi H8/300 or H8/500 simulator -@cindex simulator, Hitachi SH -@cindex Hitachi SH simulator -When configured for debugging Hitachi microprocessor targets, -@value{GDBN} includes a CPU simulator for the target chip (a Hitachi SH, -H8/300, or H8/500). -@end ifset - -@ifset Z8K -@cindex simulator, Z8000 -@cindex Zilog Z8000 simulator -When configured for debugging Zilog Z8000 targets, @value{GDBN} includes -a Z8000 simulator. -@end ifset -@end ifclear - -@ifset Z8K -For the Z8000 family, @samp{target sim} simulates either the Z8002 (the -unsegmented variant of the Z8000 architecture) or the Z8001 (the -segmented variant). The simulator recognizes which architecture is -appropriate by inspecting the object code. -@end ifset - -@table @code -@item target sim -@kindex sim -@kindex target sim -Debug programs on a simulated CPU -@ifset GENERIC -(which CPU depends on the @value{GDBN} configuration) -@end ifset -@end table - -@noindent -After specifying this target, you can debug programs for the simulated -CPU in the same style as programs for your host computer; use the -@code{file} command to load a new program image, the @code{run} command -to run your program, and so on. - -As well as making available all the usual machine registers (see -@code{info reg}), this debugging target provides three additional items -of information as specially named registers: - -@table @code -@item cycles -Counts clock-ticks in the simulator. - -@item insts -Counts instructions run in the simulator. - -@item time -Execution time in 60ths of a second. -@end table - -You can refer to these values in @value{GDBN} expressions with the usual -conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a -conditional breakpoint that suspends only after at least 5000 -simulated clock ticks. -@end ifset diff --git a/gnu/usr.bin/gdb/doc/stabs.texinfo b/gnu/usr.bin/gdb/doc/stabs.texinfo deleted file mode 100644 index 1c8d407..0000000 --- a/gnu/usr.bin/gdb/doc/stabs.texinfo +++ /dev/null @@ -1,4035 +0,0 @@ -\input texinfo -@setfilename stabs.info - -@c @finalout - -@ifinfo -@format -START-INFO-DIR-ENTRY -* Stabs: (stabs). The "stabs" debugging information format. -END-INFO-DIR-ENTRY -@end format -@end ifinfo - -@ifinfo -This document describes the stabs debugging symbol tables. - -Copyright 1992, 1993 Free Software Foundation, Inc. -Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon, -and David MacKenzie. - -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -@ignore -Permission is granted to process this file through Tex and print the -results, provided the printed document carries copying permission -notice identical to this one except for the removal of this paragraph -(this paragraph not being relevant to the printed manual). - -@end ignore -Permission is granted to copy or distribute modified versions of this -manual under the terms of the GPL (for which purpose this text may be -regarded as a program in the language TeX). -@end ifinfo - -@setchapternewpage odd -@settitle STABS -@titlepage -@title The ``stabs'' debug format -@author Julia Menapace, Jim Kingdon, David MacKenzie -@author Cygnus Support -@page -@tex -\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$ -\xdef\manvers{\$Revision: 2.120 $} % For use in headers, footers too -{\parskip=0pt -\hfill Cygnus Support\par -\hfill \manvers\par -\hfill \TeX{}info \texinfoversion\par -} -@end tex - -@vskip 0pt plus 1filll -Copyright @copyright{} 1992, 1993 Free Software Foundation, Inc. -Contributed by Cygnus Support. - -Permission is granted to make and distribute verbatim copies of -this manual provided the copyright notice and this permission notice -are preserved on all copies. - -@end titlepage - -@ifinfo -@node Top -@top The "stabs" representation of debugging information - -This document describes the stabs debugging format. - -@menu -* Overview:: Overview of stabs -* Program Structure:: Encoding of the structure of the program -* Constants:: Constants -* Variables:: -* Types:: Type definitions -* Symbol Tables:: Symbol information in symbol tables -* Cplusplus:: Appendixes: -* Stab Types:: Symbol types in a.out files -* Symbol Descriptors:: Table of symbol descriptors -* Type Descriptors:: Table of type descriptors -* Expanded Reference:: Reference information by stab type -* Questions:: Questions and anomolies -* XCOFF Differences:: Differences between GNU stabs in a.out - and GNU stabs in XCOFF -* Sun Differences:: Differences between GNU stabs and Sun - native stabs -* Stab Sections:: In some object file formats, stabs are - in sections. -* Symbol Types Index:: Index of symbolic stab symbol type names. -@end menu -@end ifinfo - - -@node Overview -@chapter Overview of Stabs - -@dfn{Stabs} refers to a format for information that describes a program -to a debugger. This format was apparently invented by -Peter Kessler at -the University of California at Berkeley, for the @code{pdx} Pascal -debugger; the format has spread widely since then. - -This document is one of the few published sources of documentation on -stabs. It is believed to be comprehensive for stabs used by C. The -lists of symbol descriptors (@pxref{Symbol Descriptors}) and type -descriptors (@pxref{Type Descriptors}) are believed to be completely -comprehensive. Stabs for COBOL-specific features and for variant -records (used by Pascal and Modula-2) are poorly documented here. - -@c FIXME: Need to document all OS9000 stuff in GDB; see all references -@c to os9k_stabs in stabsread.c. - -Other sources of information on stabs are @cite{Dbx and Dbxtool -Interfaces}, 2nd edition, by Sun, 1988, and @cite{AIX Version 3.2 Files -Reference}, Fourth Edition, September 1992, "dbx Stabstring Grammar" in -the a.out section, page 2-31. This document is believed to incorporate -the information from those two sources except where it explicitly directs -you to them for more information. - -@menu -* Flow:: Overview of debugging information flow -* Stabs Format:: Overview of stab format -* String Field:: The string field -* C Example:: A simple example in C source -* Assembly Code:: The simple example at the assembly level -@end menu - -@node Flow -@section Overview of Debugging Information Flow - -The GNU C compiler compiles C source in a @file{.c} file into assembly -language in a @file{.s} file, which the assembler translates into -a @file{.o} file, which the linker combines with other @file{.o} files and -libraries to produce an executable file. - -With the @samp{-g} option, GCC puts in the @file{.s} file additional -debugging information, which is slightly transformed by the assembler -and linker, and carried through into the final executable. This -debugging information describes features of the source file like line -numbers, the types and scopes of variables, and function names, -parameters, and scopes. - -For some object file formats, the debugging information is encapsulated -in assembler directives known collectively as @dfn{stab} (symbol table) -directives, which are interspersed with the generated code. Stabs are -the native format for debugging information in the a.out and XCOFF -object file formats. The GNU tools can also emit stabs in the COFF and -ECOFF object file formats. - -The assembler adds the information from stabs to the symbol information -it places by default in the symbol table and the string table of the -@file{.o} file it is building. The linker consolidates the @file{.o} -files into one executable file, with one symbol table and one string -table. Debuggers use the symbol and string tables in the executable as -a source of debugging information about the program. - -@node Stabs Format -@section Overview of Stab Format - -There are three overall formats for stab assembler directives, -differentiated by the first word of the stab. The name of the directive -describes which combination of four possible data fields follows. It is -either @code{.stabs} (string), @code{.stabn} (number), or @code{.stabd} -(dot). IBM's XCOFF assembler uses @code{.stabx} (and some other -directives such as @code{.file} and @code{.bi}) instead of -@code{.stabs}, @code{.stabn} or @code{.stabd}. - -The overall format of each class of stab is: - -@example -.stabs "@var{string}",@var{type},@var{other},@var{desc},@var{value} -.stabn @var{type},@var{other},@var{desc},@var{value} -.stabd @var{type},@var{other},@var{desc} -.stabx "@var{string}",@var{value},@var{type},@var{sdb-type} -@end example - -@c what is the correct term for "current file location"? My AIX -@c assembler manual calls it "the value of the current location counter". -For @code{.stabn} and @code{.stabd}, there is no @var{string} (the -@code{n_strx} field is zero; see @ref{Symbol Tables}). For -@code{.stabd}, the @var{value} field is implicit and has the value of -the current file location. For @code{.stabx}, the @var{sdb-type} field -is unused for stabs and can always be set to zero. The @var{other} -field is almost always unused and can be set to zero. - -The number in the @var{type} field gives some basic information about -which type of stab this is (or whether it @emph{is} a stab, as opposed -to an ordinary symbol). Each valid type number defines a different stab -type; further, the stab type defines the exact interpretation of, and -possible values for, any remaining @var{string}, @var{desc}, or -@var{value} fields present in the stab. @xref{Stab Types}, for a list -in numeric order of the valid @var{type} field values for stab directives. - -@node String Field -@section The String Field - -For most stabs the string field holds the meat of the -debugging information. The flexible nature of this field -is what makes stabs extensible. For some stab types the string field -contains only a name. For other stab types the contents can be a great -deal more complex. - -The overall format of the string field for most stab types is: - -@example -"@var{name}:@var{symbol-descriptor} @var{type-information}" -@end example - -@var{name} is the name of the symbol represented by the stab; it can -contain a pair of colons (@pxref{Nested Symbols}). @var{name} can be -omitted, which means the stab represents an unnamed object. For -example, @samp{:t10=*2} defines type 10 as a pointer to type 2, but does -not give the type a name. Omitting the @var{name} field is supported by -AIX dbx and GDB after about version 4.8, but not other debuggers. GCC -sometimes uses a single space as the name instead of omitting the name -altogether; apparently that is supported by most debuggers. - -The @var{symbol-descriptor} following the @samp{:} is an alphabetic -character that tells more specifically what kind of symbol the stab -represents. If the @var{symbol-descriptor} is omitted, but type -information follows, then the stab represents a local variable. For a -list of symbol descriptors, see @ref{Symbol Descriptors}. The @samp{c} -symbol descriptor is an exception in that it is not followed by type -information. @xref{Constants}. - -@var{type-information} is either a @var{type-number}, or -@samp{@var{type-number}=}. A @var{type-number} alone is a type -reference, referring directly to a type that has already been defined. - -The @samp{@var{type-number}=} form is a type definition, where the -number represents a new type which is about to be defined. The type -definition may refer to other types by number, and those type numbers -may be followed by @samp{=} and nested definitions. Also, the Lucid -compiler will repeat @samp{@var{type-number}=} more than once if it -wants to define several type numbers at once. - -In a type definition, if the character that follows the equals sign is -non-numeric then it is a @var{type-descriptor}, and tells what kind of -type is about to be defined. Any other values following the -@var{type-descriptor} vary, depending on the @var{type-descriptor}. -@xref{Type Descriptors}, for a list of @var{type-descriptor} values. If -a number follows the @samp{=} then the number is a @var{type-reference}. -For a full description of types, @ref{Types}. - -There is an AIX extension for type attributes. Following the @samp{=} -are any number of type attributes. Each one starts with @samp{@@} and -ends with @samp{;}. Debuggers, including AIX's dbx and GDB 4.10, skip -any type attributes they do not recognize. GDB 4.9 and other versions -of dbx may not do this. Because of a conflict with C++ -(@pxref{Cplusplus}), new attributes should not be defined which begin -with a digit, @samp{(}, or @samp{-}; GDB may be unable to distinguish -those from the C++ type descriptor @samp{@@}. The attributes are: - -@table @code -@item a@var{boundary} -@var{boundary} is an integer specifying the alignment. I assume it -applies to all variables of this type. - -@item p@var{integer} -Pointer class (for checking). Not sure what this means, or how -@var{integer} is interpreted. - -@item P -Indicate this is a packed type, meaning that structure fields or array -elements are placed more closely in memory, to save memory at the -expense of speed. - -@item s@var{size} -Size in bits of a variable of this type. This is fully supported by GDB -4.11 and later. - -@item S -Indicate that this type is a string instead of an array of characters, -or a bitstring instead of a set. It doesn't change the layout of the -data being represented, but does enable the debugger to know which type -it is. -@end table - -All of this can make the string field quite long. All versions of GDB, -and some versions of dbx, can handle arbitrarily long strings. But many -versions of dbx (or assemblers or linkers, I'm not sure which) -cretinously limit the strings to about 80 characters, so compilers which -must work with such systems need to split the @code{.stabs} directive -into several @code{.stabs} directives. Each stab duplicates every field -except the string field. The string field of every stab except the last -is marked as continued with a backslash at the end (in the assembly code -this may be written as a double backslash, depending on the assembler). -Removing the backslashes and concatenating the string fields of each -stab produces the original, long string. Just to be incompatible (or so -they don't have to worry about what the assembler does with -backslashes), AIX can use @samp{?} instead of backslash. - -@node C Example -@section A Simple Example in C Source - -To get the flavor of how stabs describe source information for a C -program, let's look at the simple program: - -@example -main() -@{ - printf("Hello world"); -@} -@end example - -When compiled with @samp{-g}, the program above yields the following -@file{.s} file. Line numbers have been added to make it easier to refer -to parts of the @file{.s} file in the description of the stabs that -follows. - -@node Assembly Code -@section The Simple Example at the Assembly Level - -This simple ``hello world'' example demonstrates several of the stab -types used to describe C language source files. - -@example -1 gcc2_compiled.: -2 .stabs "/cygint/s1/users/jcm/play/",100,0,0,Ltext0 -3 .stabs "hello.c",100,0,0,Ltext0 -4 .text -5 Ltext0: -6 .stabs "int:t1=r1;-2147483648;2147483647;",128,0,0,0 -7 .stabs "char:t2=r2;0;127;",128,0,0,0 -8 .stabs "long int:t3=r1;-2147483648;2147483647;",128,0,0,0 -9 .stabs "unsigned int:t4=r1;0;-1;",128,0,0,0 -10 .stabs "long unsigned int:t5=r1;0;-1;",128,0,0,0 -11 .stabs "short int:t6=r1;-32768;32767;",128,0,0,0 -12 .stabs "long long int:t7=r1;0;-1;",128,0,0,0 -13 .stabs "short unsigned int:t8=r1;0;65535;",128,0,0,0 -14 .stabs "long long unsigned int:t9=r1;0;-1;",128,0,0,0 -15 .stabs "signed char:t10=r1;-128;127;",128,0,0,0 -16 .stabs "unsigned char:t11=r1;0;255;",128,0,0,0 -17 .stabs "float:t12=r1;4;0;",128,0,0,0 -18 .stabs "double:t13=r1;8;0;",128,0,0,0 -19 .stabs "long double:t14=r1;8;0;",128,0,0,0 -20 .stabs "void:t15=15",128,0,0,0 -21 .align 4 -22 LC0: -23 .ascii "Hello, world!\12\0" -24 .align 4 -25 .global _main -26 .proc 1 -27 _main: -28 .stabn 68,0,4,LM1 -29 LM1: -30 !#PROLOGUE# 0 -31 save %sp,-136,%sp -32 !#PROLOGUE# 1 -33 call ___main,0 -34 nop -35 .stabn 68,0,5,LM2 -36 LM2: -37 LBB2: -38 sethi %hi(LC0),%o1 -39 or %o1,%lo(LC0),%o0 -40 call _printf,0 -41 nop -42 .stabn 68,0,6,LM3 -43 LM3: -44 LBE2: -45 .stabn 68,0,6,LM4 -46 LM4: -47 L1: -48 ret -49 restore -50 .stabs "main:F1",36,0,0,_main -51 .stabn 192,0,0,LBB2 -52 .stabn 224,0,0,LBE2 -@end example - -@node Program Structure -@chapter Encoding the Structure of the Program - -The elements of the program structure that stabs encode include the name -of the main function, the names of the source and include files, the -line numbers, procedure names and types, and the beginnings and ends of -blocks of code. - -@menu -* Main Program:: Indicate what the main program is -* Source Files:: The path and name of the source file -* Include Files:: Names of include files -* Line Numbers:: -* Procedures:: -* Nested Procedures:: -* Block Structure:: -* Alternate Entry Points:: Entering procedures except at the beginning. -@end menu - -@node Main Program -@section Main Program - -@findex N_MAIN -Most languages allow the main program to have any name. The -@code{N_MAIN} stab type tells the debugger the name that is used in this -program. Only the string field is significant; it is the name of -a function which is the main program. Most C compilers do not use this -stab (they expect the debugger to assume that the name is @code{main}), -but some C compilers emit an @code{N_MAIN} stab for the @code{main} -function. - -@node Source Files -@section Paths and Names of the Source Files - -@findex N_SO -Before any other stabs occur, there must be a stab specifying the source -file. This information is contained in a symbol of stab type -@code{N_SO}; the string field contains the name of the file. The -value of the symbol is the start address of the portion of the -text section corresponding to that file. - -With the Sun Solaris2 compiler, the desc field contains a -source-language code. -@c Do the debuggers use it? What are the codes? -djm - -Some compilers (for example, GCC2 and SunOS4 @file{/bin/cc}) also -include the directory in which the source was compiled, in a second -@code{N_SO} symbol preceding the one containing the file name. This -symbol can be distinguished by the fact that it ends in a slash. Code -from the @code{cfront} C++ compiler can have additional @code{N_SO} symbols for -nonexistent source files after the @code{N_SO} for the real source file; -these are believed to contain no useful information. - -For example: - -@example -.stabs "/cygint/s1/users/jcm/play/",100,0,0,Ltext0 # @r{100 is N_SO} -.stabs "hello.c",100,0,0,Ltext0 - .text -Ltext0: -@end example - -Instead of @code{N_SO} symbols, XCOFF uses a @code{.file} assembler -directive which assembles to a standard COFF @code{.file} symbol; -explaining this in detail is outside the scope of this document. - -@node Include Files -@section Names of Include Files - -There are several schemes for dealing with include files: the -traditional @code{N_SOL} approach, Sun's @code{N_BINCL} approach, and the -XCOFF @code{C_BINCL} approach (which despite the similar name has little in -common with @code{N_BINCL}). - -@findex N_SOL -An @code{N_SOL} symbol specifies which include file subsequent symbols -refer to. The string field is the name of the file and the value is the -text address corresponding to the end of the previous include file and -the start of this one. To specify the main source file again, use an -@code{N_SOL} symbol with the name of the main source file. - -@findex N_BINCL -@findex N_EINCL -@findex N_EXCL -The @code{N_BINCL} approach works as follows. An @code{N_BINCL} symbol -specifies the start of an include file. In an object file, only the -string is significant; the Sun linker puts data into some of the -other fields. The end of the include file is marked by an -@code{N_EINCL} symbol (which has no string field). In an object -file, there is no significant data in the @code{N_EINCL} symbol; the Sun -linker puts data into some of the fields. @code{N_BINCL} and -@code{N_EINCL} can be nested. - -If the linker detects that two source files have identical stabs between -an @code{N_BINCL} and @code{N_EINCL} pair (as will generally be the case -for a header file), then it only puts out the stabs once. Each -additional occurance is replaced by an @code{N_EXCL} symbol. I believe -the Sun (SunOS4, not sure about Solaris) linker is the only one which -supports this feature. -@c What do the fields of N_EXCL contain? -djm - -@findex C_BINCL -@findex C_EINCL -For the start of an include file in XCOFF, use the @file{.bi} assembler -directive, which generates a @code{C_BINCL} symbol. A @file{.ei} -directive, which generates a @code{C_EINCL} symbol, denotes the end of -the include file. Both directives are followed by the name of the -source file in quotes, which becomes the string for the symbol. -The value of each symbol, produced automatically by the assembler -and linker, is the offset into the executable of the beginning -(inclusive, as you'd expect) or end (inclusive, as you would not expect) -of the portion of the COFF line table that corresponds to this include -file. @code{C_BINCL} and @code{C_EINCL} do not nest. - -@node Line Numbers -@section Line Numbers - -@findex N_SLINE -An @code{N_SLINE} symbol represents the start of a source line. The -desc field contains the line number and the value contains the code -address for the start of that source line. On most machines the address -is absolute; for stabs in sections (@pxref{Stab Sections}), it is -relative to the function in which the @code{N_SLINE} symbol occurs. - -@findex N_DSLINE -@findex N_BSLINE -GNU documents @code{N_DSLINE} and @code{N_BSLINE} symbols for line -numbers in the data or bss segments, respectively. They are identical -to @code{N_SLINE} but are relocated differently by the linker. They -were intended to be used to describe the source location of a variable -declaration, but I believe that GCC2 actually puts the line number in -the desc field of the stab for the variable itself. GDB has been -ignoring these symbols (unless they contain a string field) since -at least GDB 3.5. - -For single source lines that generate discontiguous code, such as flow -of control statements, there may be more than one line number entry for -the same source line. In this case there is a line number entry at the -start of each code range, each with the same line number. - -XCOFF does not use stabs for line numbers. Instead, it uses COFF line -numbers (which are outside the scope of this document). Standard COFF -line numbers cannot deal with include files, but in XCOFF this is fixed -with the @code{C_BINCL} method of marking include files (@pxref{Include -Files}). - -@node Procedures -@section Procedures - -@findex N_FUN, for functions -@findex N_FNAME -@findex N_STSYM, for functions (Sun acc) -@findex N_GSYM, for functions (Sun acc) -All of the following stabs normally use the @code{N_FUN} symbol type. -However, Sun's @code{acc} compiler on SunOS4 uses @code{N_GSYM} and -@code{N_STSYM}, which means that the value of the stab for the function -is useless and the debugger must get the address of the function from -the non-stab symbols instead. BSD Fortran is said to use @code{N_FNAME} -with the same restriction; the value of the symbol is not useful (I'm -not sure it really does use this, because GDB doesn't handle this and no -one has complained). - -A function is represented by an @samp{F} symbol descriptor for a global -(extern) function, and @samp{f} for a static (local) function. The -value is the address of the start of the function. For a.out, it -is already relocated. For stabs in ELF, the SunPRO compiler version -2.0.1 and GCC put out an address which gets relocated by the linker. In -a future release SunPRO is planning to put out zero, in which case the -address can be found from the ELF (non-stab) symbol. Because looking -things up in the ELF symbols would probably be slow, I'm not sure how to -find which symbol of that name is the right one, and this doesn't -provide any way to deal with nested functions, it would probably be -better to make the value of the stab an address relative to the start of -the file, or just absolute. See @ref{ELF Linker Relocation} for more -information on linker relocation of stabs in ELF files. - -The type information of the stab represents the return type of the -function; thus @samp{foo:f5} means that foo is a function returning type -5. There is no need to try to get the line number of the start of the -function from the stab for the function; it is in the next -@code{N_SLINE} symbol. - -@c FIXME: verify whether the "I suspect" below is true or not. -Some compilers (such as Sun's Solaris compiler) support an extension for -specifying the types of the arguments. I suspect this extension is not -used for old (non-prototyped) function definitions in C. If the -extension is in use, the type information of the stab for the function -is followed by type information for each argument, with each argument -preceded by @samp{;}. An argument type of 0 means that additional -arguments are being passed, whose types and number may vary (@samp{...} -in ANSI C). GDB has tolerated this extension (parsed the syntax, if not -necessarily used the information) since at least version 4.8; I don't -know whether all versions of dbx tolerate it. The argument types given -here are not redundant with the symbols for the formal parameters -(@pxref{Parameters}); they are the types of the arguments as they are -passed, before any conversions might take place. For example, if a C -function which is declared without a prototype takes a @code{float} -argument, the value is passed as a @code{double} but then converted to a -@code{float}. Debuggers need to use the types given in the arguments -when printing values, but when calling the function they need to use the -types given in the symbol defining the function. - -If the return type and types of arguments of a function which is defined -in another source file are specified (i.e., a function prototype in ANSI -C), traditionally compilers emit no stab; the only way for the debugger -to find the information is if the source file where the function is -defined was also compiled with debugging symbols. As an extension the -Solaris compiler uses symbol descriptor @samp{P} followed by the return -type of the function, followed by the arguments, each preceded by -@samp{;}, as in a stab with symbol descriptor @samp{f} or @samp{F}. -This use of symbol descriptor @samp{P} can be distinguished from its use -for register parameters (@pxref{Register Parameters}) by the fact that it has -symbol type @code{N_FUN}. - -The AIX documentation also defines symbol descriptor @samp{J} as an -internal function. I assume this means a function nested within another -function. It also says symbol descriptor @samp{m} is a module in -Modula-2 or extended Pascal. - -Procedures (functions which do not return values) are represented as -functions returning the @code{void} type in C. I don't see why this couldn't -be used for all languages (inventing a @code{void} type for this purpose if -necessary), but the AIX documentation defines @samp{I}, @samp{P}, and -@samp{Q} for internal, global, and static procedures, respectively. -These symbol descriptors are unusual in that they are not followed by -type information. - -The following example shows a stab for a function @code{main} which -returns type number @code{1}. The @code{_main} specified for the value -is a reference to an assembler label which is used to fill in the start -address of the function. - -@example -.stabs "main:F1",36,0,0,_main # @r{36 is N_FUN} -@end example - -The stab representing a procedure is located immediately following the -code of the procedure. This stab is in turn directly followed by a -group of other stabs describing elements of the procedure. These other -stabs describe the procedure's parameters, its block local variables, and -its block structure. - -@node Nested Procedures -@section Nested Procedures - -For any of the symbol descriptors representing procedures, after the -symbol descriptor and the type information is optionally a scope -specifier. This consists of a comma, the name of the procedure, another -comma, and the name of the enclosing procedure. The first name is local -to the scope specified, and seems to be redundant with the name of the -symbol (before the @samp{:}). This feature is used by GCC, and -presumably Pascal, Modula-2, etc., compilers, for nested functions. - -If procedures are nested more than one level deep, only the immediately -containing scope is specified. For example, this code: - -@example -int -foo (int x) -@{ - int bar (int y) - @{ - int baz (int z) - @{ - return x + y + z; - @} - return baz (x + 2 * y); - @} - return x + bar (3 * x); -@} -@end example - -@noindent -produces the stabs: - -@example -.stabs "baz:f1,baz,bar",36,0,0,_baz.15 # @r{36 is N_FUN} -.stabs "bar:f1,bar,foo",36,0,0,_bar.12 -.stabs "foo:F1",36,0,0,_foo -@end example - -@node Block Structure -@section Block Structure - -@findex N_LBRAC -@findex N_RBRAC -@c For GCC 2.5.8 or so stabs-in-coff, these are absolute instead of -@c function relative (as documented below). But GDB has never been able -@c to deal with that (it had wanted them to be relative to the file, but -@c I just fixed that (between GDB 4.12 and 4.13)), so it is function -@c relative just like ELF and SOM and the below documentation. -The program's block structure is represented by the @code{N_LBRAC} (left -brace) and the @code{N_RBRAC} (right brace) stab types. The variables -defined inside a block precede the @code{N_LBRAC} symbol for most -compilers, including GCC. Other compilers, such as the Convex, Acorn -RISC machine, and Sun @code{acc} compilers, put the variables after the -@code{N_LBRAC} symbol. The values of the @code{N_LBRAC} and -@code{N_RBRAC} symbols are the start and end addresses of the code of -the block, respectively. For most machines, they are relative to the -starting address of this source file. For the Gould NP1, they are -absolute. For stabs in sections (@pxref{Stab Sections}), they are -relative to the function in which they occur. - -The @code{N_LBRAC} and @code{N_RBRAC} stabs that describe the block -scope of a procedure are located after the @code{N_FUN} stab that -represents the procedure itself. - -Sun documents the desc field of @code{N_LBRAC} and -@code{N_RBRAC} symbols as containing the nesting level of the block. -However, dbx seems to not care, and GCC always sets desc to -zero. - -@node Alternate Entry Points -@section Alternate Entry Points - -Some languages, like Fortran, have the ability to enter procedures at -some place other than the beginning. One can declare an alternate entry -point. The @code{N_ENTRY} stab is for this; however, the Sun FORTRAN compiler -doesn't use it. According to AIX documentation, only the name of a -@code{C_ENTRY} stab is significant; the address of the alternate entry -point comes from the corresponding external symbol. A previous revision -of this document said that the value of an @code{N_ENTRY} stab was the -address of the alternate entry point, but I don't know the source for -that information. - -@node Constants -@chapter Constants - -The @samp{c} symbol descriptor indicates that this stab represents a -constant. This symbol descriptor is an exception to the general rule -that symbol descriptors are followed by type information. Instead, it -is followed by @samp{=} and one of the following: - -@table @code -@item b @var{value} -Boolean constant. @var{value} is a numeric value; I assume it is 0 for -false or 1 for true. - -@item c @var{value} -Character constant. @var{value} is the numeric value of the constant. - -@item e @var{type-information} , @var{value} -Constant whose value can be represented as integral. -@var{type-information} is the type of the constant, as it would appear -after a symbol descriptor (@pxref{String Field}). @var{value} is the -numeric value of the constant. GDB 4.9 does not actually get the right -value if @var{value} does not fit in a host @code{int}, but it does not -do anything violent, and future debuggers could be extended to accept -integers of any size (whether unsigned or not). This constant type is -usually documented as being only for enumeration constants, but GDB has -never imposed that restriction; I don't know about other debuggers. - -@item i @var{value} -Integer constant. @var{value} is the numeric value. The type is some -sort of generic integer type (for GDB, a host @code{int}); to specify -the type explicitly, use @samp{e} instead. - -@item r @var{value} -Real constant. @var{value} is the real value, which can be @samp{INF} -(optionally preceded by a sign) for infinity, @samp{QNAN} for a quiet -NaN (not-a-number), or @samp{SNAN} for a signalling NaN. If it is a -normal number the format is that accepted by the C library function -@code{atof}. - -@item s @var{string} -String constant. @var{string} is a string enclosed in either @samp{'} -(in which case @samp{'} characters within the string are represented as -@samp{\'} or @samp{"} (in which case @samp{"} characters within the -string are represented as @samp{\"}). - -@item S @var{type-information} , @var{elements} , @var{bits} , @var{pattern} -Set constant. @var{type-information} is the type of the constant, as it -would appear after a symbol descriptor (@pxref{String Field}). -@var{elements} is the number of elements in the set (does this means -how many bits of @var{pattern} are actually used, which would be -redundant with the type, or perhaps the number of bits set in -@var{pattern}? I don't get it), @var{bits} is the number of bits in the -constant (meaning it specifies the length of @var{pattern}, I think), -and @var{pattern} is a hexadecimal representation of the set. AIX -documentation refers to a limit of 32 bytes, but I see no reason why -this limit should exist. This form could probably be used for arbitrary -constants, not just sets; the only catch is that @var{pattern} should be -understood to be target, not host, byte order and format. -@end table - -The boolean, character, string, and set constants are not supported by -GDB 4.9, but it ignores them. GDB 4.8 and earlier gave an error -message and refused to read symbols from the file containing the -constants. - -The above information is followed by @samp{;}. - -@node Variables -@chapter Variables - -Different types of stabs describe the various ways that variables can be -allocated: on the stack, globally, in registers, in common blocks, -statically, or as arguments to a function. - -@menu -* Stack Variables:: Variables allocated on the stack. -* Global Variables:: Variables used by more than one source file. -* Register Variables:: Variables in registers. -* Common Blocks:: Variables statically allocated together. -* Statics:: Variables local to one source file. -* Based Variables:: Fortran pointer based variables. -* Parameters:: Variables for arguments to functions. -@end menu - -@node Stack Variables -@section Automatic Variables Allocated on the Stack - -If a variable's scope is local to a function and its lifetime is only as -long as that function executes (C calls such variables -@dfn{automatic}), it can be allocated in a register (@pxref{Register -Variables}) or on the stack. - -@findex N_LSYM -Each variable allocated on the stack has a stab with the symbol -descriptor omitted. Since type information should begin with a digit, -@samp{-}, or @samp{(}, only those characters precluded from being used -for symbol descriptors. However, the Acorn RISC machine (ARM) is said -to get this wrong: it puts out a mere type definition here, without the -preceding @samp{@var{type-number}=}. This is a bad idea; there is no -guarantee that type descriptors are distinct from symbol descriptors. -Stabs for stack variables use the @code{N_LSYM} stab type. - -The value of the stab is the offset of the variable within the -local variables. On most machines this is an offset from the frame -pointer and is negative. The location of the stab specifies which block -it is defined in; see @ref{Block Structure}. - -For example, the following C code: - -@example -int -main () -@{ - int x; -@} -@end example - -produces the following stabs: - -@example -.stabs "main:F1",36,0,0,_main # @r{36 is N_FUN} -.stabs "x:1",128,0,0,-12 # @r{128 is N_LSYM} -.stabn 192,0,0,LBB2 # @r{192 is N_LBRAC} -.stabn 224,0,0,LBE2 # @r{224 is N_RBRAC} -@end example - -@xref{Procedures} for more information on the @code{N_FUN} stab, and -@ref{Block Structure} for more information on the @code{N_LBRAC} and -@code{N_RBRAC} stabs. - -@node Global Variables -@section Global Variables - -@findex N_GSYM -A variable whose scope is not specific to just one source file is -represented by the @samp{G} symbol descriptor. These stabs use the -@code{N_GSYM} stab type. The type information for the stab -(@pxref{String Field}) gives the type of the variable. - -For example, the following source code: - -@example -char g_foo = 'c'; -@end example - -@noindent -yields the following assembly code: - -@example -.stabs "g_foo:G2",32,0,0,0 # @r{32 is N_GSYM} - .global _g_foo - .data -_g_foo: - .byte 99 -@end example - -The address of the variable represented by the @code{N_GSYM} is not -contained in the @code{N_GSYM} stab. The debugger gets this information -from the external symbol for the global variable. In the example above, -the @code{.global _g_foo} and @code{_g_foo:} lines tell the assembler to -produce an external symbol. - -Some compilers, like GCC, output @code{N_GSYM} stabs only once, where -the variable is defined. Other compilers, like SunOS4 /bin/cc, output a -@code{N_GSYM} stab for each compilation unit which references the -variable. - -@node Register Variables -@section Register Variables - -@findex N_RSYM -@c According to an old version of this manual, AIX uses C_RPSYM instead -@c of C_RSYM. I am skeptical; this should be verified. -Register variables have their own stab type, @code{N_RSYM}, and their -own symbol descriptor, @samp{r}. The stab's value is the -number of the register where the variable data will be stored. -@c .stabs "name:type",N_RSYM,0,RegSize,RegNumber (Sun doc) - -AIX defines a separate symbol descriptor @samp{d} for floating point -registers. This seems unnecessary; why not just just give floating -point registers different register numbers? I have not verified whether -the compiler actually uses @samp{d}. - -If the register is explicitly allocated to a global variable, but not -initialized, as in: - -@example -register int g_bar asm ("%g5"); -@end example - -@noindent -then the stab may be emitted at the end of the object file, with -the other bss symbols. - -@node Common Blocks -@section Common Blocks - -A common block is a statically allocated section of memory which can be -referred to by several source files. It may contain several variables. -I believe Fortran is the only language with this feature. - -@findex N_BCOMM -@findex N_ECOMM -@findex C_BCOMM -@findex C_ECOMM -A @code{N_BCOMM} stab begins a common block and an @code{N_ECOMM} stab -ends it. The only field that is significant in these two stabs is the -string, which names a normal (non-debugging) symbol that gives the -address of the common block. According to IBM documentation, only the -@code{N_BCOMM} has the name of the common block (even though their -compiler actually puts it both places). - -@findex N_ECOML -@findex C_ECOML -The stabs for the members of the common block are between the -@code{N_BCOMM} and the @code{N_ECOMM}; the value of each stab is the -offset within the common block of that variable. IBM uses the -@code{C_ECOML} stab type, and there is a corresponding @code{N_ECOML} -stab type, but Sun's Fortran compiler uses @code{N_GSYM} instead. The -variables within a common block use the @samp{V} symbol descriptor (I -believe this is true of all Fortran variables). Other stabs (at least -type declarations using @code{C_DECL}) can also be between the -@code{N_BCOMM} and the @code{N_ECOMM}. - -@node Statics -@section Static Variables - -Initialized static variables are represented by the @samp{S} and -@samp{V} symbol descriptors. @samp{S} means file scope static, and -@samp{V} means procedure scope static. One exception: in XCOFF, IBM's -xlc compiler always uses @samp{V}, and whether it is file scope or not -is distinguished by whether the stab is located within a function. - -@c This is probably not worth mentioning; it is only true on the sparc -@c for `double' variables which although declared const are actually in -@c the data segment (the text segment can't guarantee 8 byte alignment). -@c (although GCC -@c 2.4.5 has a bug in that it uses @code{N_FUN}, so neither dbx nor GDB can -@c find the variables) -@findex N_STSYM -@findex N_LCSYM -@findex N_FUN, for variables -@findex N_ROSYM -In a.out files, @code{N_STSYM} means the data section, @code{N_FUN} -means the text section, and @code{N_LCSYM} means the bss section. For -those systems with a read-only data section separate from the text -section (Solaris), @code{N_ROSYM} means the read-only data section. - -For example, the source lines: - -@example -static const int var_const = 5; -static int var_init = 2; -static int var_noinit; -@end example - -@noindent -yield the following stabs: - -@example -.stabs "var_const:S1",36,0,0,_var_const # @r{36 is N_FUN} -@dots{} -.stabs "var_init:S1",38,0,0,_var_init # @r{38 is N_STSYM} -@dots{} -.stabs "var_noinit:S1",40,0,0,_var_noinit # @r{40 is N_LCSYM} -@end example - -In XCOFF files, the stab type need not indicate the section; -@code{C_STSYM} can be used for all statics. Also, each static variable -is enclosed in a static block. A @code{C_BSTAT} (emitted with a -@samp{.bs} assembler directive) symbol begins the static block; its -value is the symbol number of the csect symbol whose value is the -address of the static block, its section is the section of the variables -in that static block, and its name is @samp{.bs}. A @code{C_ESTAT} -(emitted with a @samp{.es} assembler directive) symbol ends the static -block; its name is @samp{.es} and its value and section are ignored. - -In ECOFF files, the storage class is used to specify the section, so the -stab type need not indicate the section. - -In ELF files, for the SunPRO compiler version 2.0.1, symbol descriptor -@samp{S} means that the address is absolute (the linker relocates it) -and symbol descriptor @samp{V} means that the address is relative to the -start of the relevant section for that compilation unit. SunPRO has -plans to have the linker stop relocating stabs; I suspect that their the -debugger gets the address from the corresponding ELF (not stab) symbol. -I'm not sure how to find which symbol of that name is the right one. -The clean way to do all this would be to have a the value of a symbol -descriptor @samp{S} symbol be an offset relative to the start of the -file, just like everything else, but that introduces obvious -compatibility problems. For more information on linker stab relocation, -@xref{ELF Linker Relocation}. - -@node Based Variables -@section Fortran Based Variables - -Fortran (at least, the Sun and SGI dialects of FORTRAN-77) has a feature -which allows allocating arrays with @code{malloc}, but which avoids -blurring the line between arrays and pointers the way that C does. In -stabs such a variable uses the @samp{b} symbol descriptor. - -For example, the Fortran declarations - -@example -real foo, foo10(10), foo10_5(10,5) -pointer (foop, foo) -pointer (foo10p, foo10) -pointer (foo105p, foo10_5) -@end example - -produce the stabs - -@example -foo:b6 -foo10:bar3;1;10;6 -foo10_5:bar3;1;5;ar3;1;10;6 -@end example - -In this example, @code{real} is type 6 and type 3 is an integral type -which is the type of the subscripts of the array (probably -@code{integer}). - -The @samp{b} symbol descriptor is like @samp{V} in that it denotes a -statically allocated symbol whose scope is local to a function; see -@xref{Statics}. The value of the symbol, instead of being the address -of the variable itself, is the address of a pointer to that variable. -So in the above example, the value of the @code{foo} stab is the address -of a pointer to a real, the value of the @code{foo10} stab is the -address of a pointer to a 10-element array of reals, and the value of -the @code{foo10_5} stab is the address of a pointer to a 5-element array -of 10-element arrays of reals. - -@node Parameters -@section Parameters - -Formal parameters to a function are represented by a stab (or sometimes -two; see below) for each parameter. The stabs are in the order in which -the debugger should print the parameters (i.e., the order in which the -parameters are declared in the source file). The exact form of the stab -depends on how the parameter is being passed. - -@findex N_PSYM -Parameters passed on the stack use the symbol descriptor @samp{p} and -the @code{N_PSYM} symbol type. The value of the symbol is an offset -used to locate the parameter on the stack; its exact meaning is -machine-dependent, but on most machines it is an offset from the frame -pointer. - -As a simple example, the code: - -@example -main (argc, argv) - int argc; - char **argv; -@end example - -produces the stabs: - -@example -.stabs "main:F1",36,0,0,_main # @r{36 is N_FUN} -.stabs "argc:p1",160,0,0,68 # @r{160 is N_PSYM} -.stabs "argv:p20=*21=*2",160,0,0,72 -@end example - -The type definition of @code{argv} is interesting because it contains -several type definitions. Type 21 is pointer to type 2 (char) and -@code{argv} (type 20) is pointer to type 21. - -@c FIXME: figure out what these mean and describe them coherently. -The following symbol descriptors are also said to go with @code{N_PSYM}. -The value of the symbol is said to be an offset from the argument -pointer (I'm not sure whether this is true or not). - -@example -pP (<<??>>) -pF Fortran function parameter -X (function result variable) -@end example - -@menu -* Register Parameters:: -* Local Variable Parameters:: -* Reference Parameters:: -* Conformant Arrays:: -@end menu - -@node Register Parameters -@subsection Passing Parameters in Registers - -If the parameter is passed in a register, then traditionally there are -two symbols for each argument: - -@example -.stabs "arg:p1" . . . ; N_PSYM -.stabs "arg:r1" . . . ; N_RSYM -@end example - -Debuggers use the second one to find the value, and the first one to -know that it is an argument. - -@findex C_RPSYM -@findex N_RSYM, for parameters -Because that approach is kind of ugly, some compilers use symbol -descriptor @samp{P} or @samp{R} to indicate an argument which is in a -register. Symbol type @code{C_RPSYM} is used with @samp{R} and -@code{N_RSYM} is used with @samp{P}. The symbol's value is -the register number. @samp{P} and @samp{R} mean the same thing; the -difference is that @samp{P} is a GNU invention and @samp{R} is an IBM -(XCOFF) invention. As of version 4.9, GDB should handle either one. - -There is at least one case where GCC uses a @samp{p} and @samp{r} pair -rather than @samp{P}; this is where the argument is passed in the -argument list and then loaded into a register. - -According to the AIX documentation, symbol descriptor @samp{D} is for a -parameter passed in a floating point register. This seems -unnecessary---why not just use @samp{R} with a register number which -indicates that it's a floating point register? I haven't verified -whether the system actually does what the documentation indicates. - -@c FIXME: On the hppa this is for any type > 8 bytes, I think, and not -@c for small structures (investigate). -On the sparc and hppa, for a @samp{P} symbol whose type is a structure -or union, the register contains the address of the structure. On the -sparc, this is also true of a @samp{p} and @samp{r} pair (using Sun -@code{cc}) or a @samp{p} symbol. However, if a (small) structure is -really in a register, @samp{r} is used. And, to top it all off, on the -hppa it might be a structure which was passed on the stack and loaded -into a register and for which there is a @samp{p} and @samp{r} pair! I -believe that symbol descriptor @samp{i} is supposed to deal with this -case (it is said to mean "value parameter by reference, indirect -access"; I don't know the source for this information), but I don't know -details or what compilers or debuggers use it, if any (not GDB or GCC). -It is not clear to me whether this case needs to be dealt with -differently than parameters passed by reference (@pxref{Reference Parameters}). - -@node Local Variable Parameters -@subsection Storing Parameters as Local Variables - -There is a case similar to an argument in a register, which is an -argument that is actually stored as a local variable. Sometimes this -happens when the argument was passed in a register and then the compiler -stores it as a local variable. If possible, the compiler should claim -that it's in a register, but this isn't always done. - -If a parameter is passed as one type and converted to a smaller type by -the prologue (for example, the parameter is declared as a @code{float}, -but the calling conventions specify that it is passed as a -@code{double}), then GCC2 (sometimes) uses a pair of symbols. The first -symbol uses symbol descriptor @samp{p} and the type which is passed. -The second symbol has the type and location which the parameter actually -has after the prologue. For example, suppose the following C code -appears with no prototypes involved: - -@example -void -subr (f) - float f; -@{ -@end example - -if @code{f} is passed as a double at stack offset 8, and the prologue -converts it to a float in register number 0, then the stabs look like: - -@example -.stabs "f:p13",160,0,3,8 # @r{160 is @code{N_PSYM}, here 13 is @code{double}} -.stabs "f:r12",64,0,3,0 # @r{64 is @code{N_RSYM}, here 12 is @code{float}} -@end example - -In both stabs 3 is the line number where @code{f} is declared -(@pxref{Line Numbers}). - -@findex N_LSYM, for parameter -GCC, at least on the 960, has another solution to the same problem. It -uses a single @samp{p} symbol descriptor for an argument which is stored -as a local variable but uses @code{N_LSYM} instead of @code{N_PSYM}. In -this case, the value of the symbol is an offset relative to the local -variables for that function, not relative to the arguments; on some -machines those are the same thing, but not on all. - -@c This is mostly just background info; the part that logically belongs -@c here is the last sentence. -On the VAX or on other machines in which the calling convention includes -the number of words of arguments actually passed, the debugger (GDB at -least) uses the parameter symbols to keep track of whether it needs to -print nameless arguments in addition to the formal parameters which it -has printed because each one has a stab. For example, in - -@example -extern int fprintf (FILE *stream, char *format, @dots{}); -@dots{} -fprintf (stdout, "%d\n", x); -@end example - -there are stabs for @code{stream} and @code{format}. On most machines, -the debugger can only print those two arguments (because it has no way -of knowing that additional arguments were passed), but on the VAX or -other machines with a calling convention which indicates the number of -words of arguments, the debugger can print all three arguments. To do -so, the parameter symbol (symbol descriptor @samp{p}) (not necessarily -@samp{r} or symbol descriptor omitted symbols) needs to contain the -actual type as passed (for example, @code{double} not @code{float} if it -is passed as a double and converted to a float). - -@node Reference Parameters -@subsection Passing Parameters by Reference - -If the parameter is passed by reference (e.g., Pascal @code{VAR} -parameters), then the symbol descriptor is @samp{v} if it is in the -argument list, or @samp{a} if it in a register. Other than the fact -that these contain the address of the parameter rather than the -parameter itself, they are identical to @samp{p} and @samp{R}, -respectively. I believe @samp{a} is an AIX invention; @samp{v} is -supported by all stabs-using systems as far as I know. - -@node Conformant Arrays -@subsection Passing Conformant Array Parameters - -@c Is this paragraph correct? It is based on piecing together patchy -@c information and some guesswork -Conformant arrays are a feature of Modula-2, and perhaps other -languages, in which the size of an array parameter is not known to the -called function until run-time. Such parameters have two stabs: a -@samp{x} for the array itself, and a @samp{C}, which represents the size -of the array. The value of the @samp{x} stab is the offset in the -argument list where the address of the array is stored (it this right? -it is a guess); the value of the @samp{C} stab is the offset in the -argument list where the size of the array (in elements? in bytes?) is -stored. - -@node Types -@chapter Defining Types - -The examples so far have described types as references to previously -defined types, or defined in terms of subranges of or pointers to -previously defined types. This chapter describes the other type -descriptors that may follow the @samp{=} in a type definition. - -@menu -* Builtin Types:: Integers, floating point, void, etc. -* Miscellaneous Types:: Pointers, sets, files, etc. -* Cross-References:: Referring to a type not yet defined. -* Subranges:: A type with a specific range. -* Arrays:: An aggregate type of same-typed elements. -* Strings:: Like an array but also has a length. -* Enumerations:: Like an integer but the values have names. -* Structures:: An aggregate type of different-typed elements. -* Typedefs:: Giving a type a name. -* Unions:: Different types sharing storage. -* Function Types:: -@end menu - -@node Builtin Types -@section Builtin Types - -Certain types are built in (@code{int}, @code{short}, @code{void}, -@code{float}, etc.); the debugger recognizes these types and knows how -to handle them. Thus, don't be surprised if some of the following ways -of specifying builtin types do not specify everything that a debugger -would need to know about the type---in some cases they merely specify -enough information to distinguish the type from other types. - -The traditional way to define builtin types is convolunted, so new ways -have been invented to describe them. Sun's @code{acc} uses special -builtin type descriptors (@samp{b} and @samp{R}), and IBM uses negative -type numbers. GDB accepts all three ways, as of version 4.8; dbx just -accepts the traditional builtin types and perhaps one of the other two -formats. The following sections describe each of these formats. - -@menu -* Traditional Builtin Types:: Put on your seatbelts and prepare for kludgery -* Builtin Type Descriptors:: Builtin types with special type descriptors -* Negative Type Numbers:: Builtin types using negative type numbers -@end menu - -@node Traditional Builtin Types -@subsection Traditional Builtin Types - -This is the traditional, convoluted method for defining builtin types. -There are several classes of such type definitions: integer, floating -point, and @code{void}. - -@menu -* Traditional Integer Types:: -* Traditional Other Types:: -@end menu - -@node Traditional Integer Types -@subsubsection Traditional Integer Types - -Often types are defined as subranges of themselves. If the bounding values -fit within an @code{int}, then they are given normally. For example: - -@example -.stabs "int:t1=r1;-2147483648;2147483647;",128,0,0,0 # @r{128 is N_LSYM} -.stabs "char:t2=r2;0;127;",128,0,0,0 -@end example - -Builtin types can also be described as subranges of @code{int}: - -@example -.stabs "unsigned short:t6=r1;0;65535;",128,0,0,0 -@end example - -If the lower bound of a subrange is 0 and the upper bound is -1, -the type is an unsigned integral type whose bounds are too -big to describe in an @code{int}. Traditionally this is only used for -@code{unsigned int} and @code{unsigned long}: - -@example -.stabs "unsigned int:t4=r1;0;-1;",128,0,0,0 -@end example - -For larger types, GCC 2.4.5 puts out bounds in octal, with one or more -leading zeroes. In this case a negative bound consists of a number -which is a 1 bit (for the sign bit) followed by a 0 bit for each bit in -the number (except the sign bit), and a positive bound is one which is a -1 bit for each bit in the number (except possibly the sign bit). All -known versions of dbx and GDB version 4 accept this (at least in the -sense of not refusing to process the file), but GDB 3.5 refuses to read -the whole file containing such symbols. So GCC 2.3.3 did not output the -proper size for these types. As an example of octal bounds, the string -fields of the stabs for 64 bit integer types look like: - -@c .stabs directives, etc., omitted to make it fit on the page. -@example -long int:t3=r1;001000000000000000000000;000777777777777777777777; -long unsigned int:t5=r1;000000000000000000000000;001777777777777777777777; -@end example - -If the lower bound of a subrange is 0 and the upper bound is negative, -the type is an unsigned integral type whose size in bytes is the -absolute value of the upper bound. I believe this is a Convex -convention for @code{unsigned long long}. - -If the lower bound of a subrange is negative and the upper bound is 0, -the type is a signed integral type whose size in bytes is -the absolute value of the lower bound. I believe this is a Convex -convention for @code{long long}. To distinguish this from a legitimate -subrange, the type should be a subrange of itself. I'm not sure whether -this is the case for Convex. - -@node Traditional Other Types -@subsubsection Traditional Other Types - -If the upper bound of a subrange is 0 and the lower bound is positive, -the type is a floating point type, and the lower bound of the subrange -indicates the number of bytes in the type: - -@example -.stabs "float:t12=r1;4;0;",128,0,0,0 -.stabs "double:t13=r1;8;0;",128,0,0,0 -@end example - -However, GCC writes @code{long double} the same way it writes -@code{double}, so there is no way to distinguish. - -@example -.stabs "long double:t14=r1;8;0;",128,0,0,0 -@end example - -Complex types are defined the same way as floating-point types; there is -no way to distinguish a single-precision complex from a double-precision -floating-point type. - -The C @code{void} type is defined as itself: - -@example -.stabs "void:t15=15",128,0,0,0 -@end example - -I'm not sure how a boolean type is represented. - -@node Builtin Type Descriptors -@subsection Defining Builtin Types Using Builtin Type Descriptors - -This is the method used by Sun's @code{acc} for defining builtin types. -These are the type descriptors to define builtin types: - -@table @code -@c FIXME: clean up description of width and offset, once we figure out -@c what they mean -@item b @var{signed} @var{char-flag} @var{width} ; @var{offset} ; @var{nbits} ; -Define an integral type. @var{signed} is @samp{u} for unsigned or -@samp{s} for signed. @var{char-flag} is @samp{c} which indicates this -is a character type, or is omitted. I assume this is to distinguish an -integral type from a character type of the same size, for example it -might make sense to set it for the C type @code{wchar_t} so the debugger -can print such variables differently (Solaris does not do this). Sun -sets it on the C types @code{signed char} and @code{unsigned char} which -arguably is wrong. @var{width} and @var{offset} appear to be for small -objects stored in larger ones, for example a @code{short} in an -@code{int} register. @var{width} is normally the number of bytes in the -type. @var{offset} seems to always be zero. @var{nbits} is the number -of bits in the type. - -Note that type descriptor @samp{b} used for builtin types conflicts with -its use for Pascal space types (@pxref{Miscellaneous Types}); they can -be distinguished because the character following the type descriptor -will be a digit, @samp{(}, or @samp{-} for a Pascal space type, or -@samp{u} or @samp{s} for a builtin type. - -@item w -Documented by AIX to define a wide character type, but their compiler -actually uses negative type numbers (@pxref{Negative Type Numbers}). - -@item R @var{fp-type} ; @var{bytes} ; -Define a floating point type. @var{fp-type} has one of the following values: - -@table @code -@item 1 (NF_SINGLE) -IEEE 32-bit (single precision) floating point format. - -@item 2 (NF_DOUBLE) -IEEE 64-bit (double precision) floating point format. - -@item 3 (NF_COMPLEX) -@item 4 (NF_COMPLEX16) -@item 5 (NF_COMPLEX32) -@c "GDB source" really means @file{include/aout/stab_gnu.h}, but trying -@c to put that here got an overfull hbox. -These are for complex numbers. A comment in the GDB source describes -them as Fortran @code{complex}, @code{double complex}, and -@code{complex*16}, respectively, but what does that mean? (i.e., Single -precision? Double precison?). - -@item 6 (NF_LDOUBLE) -Long double. This should probably only be used for Sun format -@code{long double}, and new codes should be used for other floating -point formats (@code{NF_DOUBLE} can be used if a @code{long double} is -really just an IEEE double, of course). -@end table - -@var{bytes} is the number of bytes occupied by the type. This allows a -debugger to perform some operations with the type even if it doesn't -understand @var{fp-type}. - -@item g @var{type-information} ; @var{nbits} -Documented by AIX to define a floating type, but their compiler actually -uses negative type numbers (@pxref{Negative Type Numbers}). - -@item c @var{type-information} ; @var{nbits} -Documented by AIX to define a complex type, but their compiler actually -uses negative type numbers (@pxref{Negative Type Numbers}). -@end table - -The C @code{void} type is defined as a signed integral type 0 bits long: -@example -.stabs "void:t19=bs0;0;0",128,0,0,0 -@end example -The Solaris compiler seems to omit the trailing semicolon in this case. -Getting sloppy in this way is not a swift move because if a type is -embedded in a more complex expression it is necessary to be able to tell -where it ends. - -I'm not sure how a boolean type is represented. - -@node Negative Type Numbers -@subsection Negative Type Numbers - -This is the method used in XCOFF for defining builtin types. -Since the debugger knows about the builtin types anyway, the idea of -negative type numbers is simply to give a special type number which -indicates the builtin type. There is no stab defining these types. - -There are several subtle issues with negative type numbers. - -One is the size of the type. A builtin type (for example the C types -@code{int} or @code{long}) might have different sizes depending on -compiler options, the target architecture, the ABI, etc. This issue -doesn't come up for IBM tools since (so far) they just target the -RS/6000; the sizes indicated below for each size are what the IBM -RS/6000 tools use. To deal with differing sizes, either define separate -negative type numbers for each size (which works but requires changing -the debugger, and, unless you get both AIX dbx and GDB to accept the -change, introduces an incompatibility), or use a type attribute -(@pxref{String Field}) to define a new type with the appropriate size -(which merely requires a debugger which understands type attributes, -like AIX dbx). For example, - -@example -.stabs "boolean:t10=@@s8;-16",128,0,0,0 -@end example - -defines an 8-bit boolean type, and - -@example -.stabs "boolean:t10=@@s64;-16",128,0,0,0 -@end example - -defines a 64-bit boolean type. - -A similar issue is the format of the type. This comes up most often for -floating-point types, which could have various formats (particularly -extended doubles, which vary quite a bit even among IEEE systems). -Again, it is best to define a new negative type number for each -different format; changing the format based on the target system has -various problems. One such problem is that the Alpha has both VAX and -IEEE floating types. One can easily imagine one library using the VAX -types and another library in the same executable using the IEEE types. -Another example is that the interpretation of whether a boolean is true -or false can be based on the least significant bit, most significant -bit, whether it is zero, etc., and different compilers (or different -options to the same compiler) might provide different kinds of boolean. - -The last major issue is the names of the types. The name of a given -type depends @emph{only} on the negative type number given; these do not -vary depending on the language, the target system, or anything else. -One can always define separate type numbers---in the following list you -will see for example separate @code{int} and @code{integer*4} types -which are identical except for the name. But compatibility can be -maintained by not inventing new negative type numbers and instead just -defining a new type with a new name. For example: - -@example -.stabs "CARDINAL:t10=-8",128,0,0,0 -@end example - -Here is the list of negative type numbers. The phrase @dfn{integral -type} is used to mean twos-complement (I strongly suspect that all -machines which use stabs use twos-complement; most machines use -twos-complement these days). - -@table @code -@item -1 -@code{int}, 32 bit signed integral type. - -@item -2 -@code{char}, 8 bit type holding a character. Both GDB and dbx on AIX -treat this as signed. GCC uses this type whether @code{char} is signed -or not, which seems like a bad idea. The AIX compiler (@code{xlc}) seems to -avoid this type; it uses -5 instead for @code{char}. - -@item -3 -@code{short}, 16 bit signed integral type. - -@item -4 -@code{long}, 32 bit signed integral type. - -@item -5 -@code{unsigned char}, 8 bit unsigned integral type. - -@item -6 -@code{signed char}, 8 bit signed integral type. - -@item -7 -@code{unsigned short}, 16 bit unsigned integral type. - -@item -8 -@code{unsigned int}, 32 bit unsigned integral type. - -@item -9 -@code{unsigned}, 32 bit unsigned integral type. - -@item -10 -@code{unsigned long}, 32 bit unsigned integral type. - -@item -11 -@code{void}, type indicating the lack of a value. - -@item -12 -@code{float}, IEEE single precision. - -@item -13 -@code{double}, IEEE double precision. - -@item -14 -@code{long double}, IEEE double precision. The compiler claims the size -will increase in a future release, and for binary compatibility you have -to avoid using @code{long double}. I hope when they increase it they -use a new negative type number. - -@item -15 -@code{integer}. 32 bit signed integral type. - -@item -16 -@code{boolean}. 32 bit type. GDB and GCC assume that zero is false, -one is true, and other values have unspecified meaning. I hope this -agrees with how the IBM tools use the type. - -@item -17 -@code{short real}. IEEE single precision. - -@item -18 -@code{real}. IEEE double precision. - -@item -19 -@code{stringptr}. @xref{Strings}. - -@item -20 -@code{character}, 8 bit unsigned character type. - -@item -21 -@code{logical*1}, 8 bit type. This Fortran type has a split -personality in that it is used for boolean variables, but can also be -used for unsigned integers. 0 is false, 1 is true, and other values are -non-boolean. - -@item -22 -@code{logical*2}, 16 bit type. This Fortran type has a split -personality in that it is used for boolean variables, but can also be -used for unsigned integers. 0 is false, 1 is true, and other values are -non-boolean. - -@item -23 -@code{logical*4}, 32 bit type. This Fortran type has a split -personality in that it is used for boolean variables, but can also be -used for unsigned integers. 0 is false, 1 is true, and other values are -non-boolean. - -@item -24 -@code{logical}, 32 bit type. This Fortran type has a split -personality in that it is used for boolean variables, but can also be -used for unsigned integers. 0 is false, 1 is true, and other values are -non-boolean. - -@item -25 -@code{complex}. A complex type consisting of two IEEE single-precision -floating point values. - -@item -26 -@code{complex}. A complex type consisting of two IEEE double-precision -floating point values. - -@item -27 -@code{integer*1}, 8 bit signed integral type. - -@item -28 -@code{integer*2}, 16 bit signed integral type. - -@item -29 -@code{integer*4}, 32 bit signed integral type. - -@item -30 -@code{wchar}. Wide character, 16 bits wide, unsigned (what format? -Unicode?). -@end table - -@node Miscellaneous Types -@section Miscellaneous Types - -@table @code -@item b @var{type-information} ; @var{bytes} -Pascal space type. This is documented by IBM; what does it mean? - -This use of the @samp{b} type descriptor can be distinguished -from its use for builtin integral types (@pxref{Builtin Type -Descriptors}) because the character following the type descriptor is -always a digit, @samp{(}, or @samp{-}. - -@item B @var{type-information} -A volatile-qualified version of @var{type-information}. This is -a Sun extension. References and stores to a variable with a -volatile-qualified type must not be optimized or cached; they -must occur as the user specifies them. - -@item d @var{type-information} -File of type @var{type-information}. As far as I know this is only used -by Pascal. - -@item k @var{type-information} -A const-qualified version of @var{type-information}. This is a Sun -extension. A variable with a const-qualified type cannot be modified. - -@item M @var{type-information} ; @var{length} -Multiple instance type. The type seems to composed of @var{length} -repetitions of @var{type-information}, for example @code{character*3} is -represented by @samp{M-2;3}, where @samp{-2} is a reference to a -character type (@pxref{Negative Type Numbers}). I'm not sure how this -differs from an array. This appears to be a Fortran feature. -@var{length} is a bound, like those in range types; see @ref{Subranges}. - -@item S @var{type-information} -Pascal set type. @var{type-information} must be a small type such as an -enumeration or a subrange, and the type is a bitmask whose length is -specified by the number of elements in @var{type-information}. - -In CHILL, if it is a bitstring instead of a set, also use the @samp{S} -type attribute (@pxref{String Field}). - -@item * @var{type-information} -Pointer to @var{type-information}. -@end table - -@node Cross-References -@section Cross-References to Other Types - -A type can be used before it is defined; one common way to deal with -that situation is just to use a type reference to a type which has not -yet been defined. - -Another way is with the @samp{x} type descriptor, which is followed by -@samp{s} for a structure tag, @samp{u} for a union tag, or @samp{e} for -a enumerator tag, followed by the name of the tag, followed by @samp{:}. -If the name contains @samp{::} between a @samp{<} and @samp{>} pair (for -C++ templates), such a @samp{::} does not end the name---only a single -@samp{:} ends the name; see @ref{Nested Symbols}. - -For example, the following C declarations: - -@example -struct foo; -struct foo *bar; -@end example - -@noindent -produce: - -@example -.stabs "bar:G16=*17=xsfoo:",32,0,0,0 -@end example - -Not all debuggers support the @samp{x} type descriptor, so on some -machines GCC does not use it. I believe that for the above example it -would just emit a reference to type 17 and never define it, but I -haven't verified that. - -Modula-2 imported types, at least on AIX, use the @samp{i} type -descriptor, which is followed by the name of the module from which the -type is imported, followed by @samp{:}, followed by the name of the -type. There is then optionally a comma followed by type information for -the type. This differs from merely naming the type (@pxref{Typedefs}) in -that it identifies the module; I don't understand whether the name of -the type given here is always just the same as the name we are giving -it, or whether this type descriptor is used with a nameless stab -(@pxref{String Field}), or what. The symbol ends with @samp{;}. - -@node Subranges -@section Subrange Types - -The @samp{r} type descriptor defines a type as a subrange of another -type. It is followed by type information for the type of which it is a -subrange, a semicolon, an integral lower bound, a semicolon, an -integral upper bound, and a semicolon. The AIX documentation does not -specify the trailing semicolon, in an effort to specify array indexes -more cleanly, but a subrange which is not an array index has always -included a trailing semicolon (@pxref{Arrays}). - -Instead of an integer, either bound can be one of the following: - -@table @code -@item A @var{offset} -The bound is passed by reference on the stack at offset @var{offset} -from the argument list. @xref{Parameters}, for more information on such -offsets. - -@item T @var{offset} -The bound is passed by value on the stack at offset @var{offset} from -the argument list. - -@item a @var{register-number} -The bound is pased by reference in register number -@var{register-number}. - -@item t @var{register-number} -The bound is passed by value in register number @var{register-number}. - -@item J -There is no bound. -@end table - -Subranges are also used for builtin types; see @ref{Traditional Builtin Types}. - -@node Arrays -@section Array Types - -Arrays use the @samp{a} type descriptor. Following the type descriptor -is the type of the index and the type of the array elements. If the -index type is a range type, it ends in a semicolon; otherwise -(for example, if it is a type reference), there does not -appear to be any way to tell where the types are separated. In an -effort to clean up this mess, IBM documents the two types as being -separated by a semicolon, and a range type as not ending in a semicolon -(but this is not right for range types which are not array indexes, -@pxref{Subranges}). I think probably the best solution is to specify -that a semicolon ends a range type, and that the index type and element -type of an array are separated by a semicolon, but that if the index -type is a range type, the extra semicolon can be omitted. GDB (at least -through version 4.9) doesn't support any kind of index type other than a -range anyway; I'm not sure about dbx. - -It is well established, and widely used, that the type of the index, -unlike most types found in the stabs, is merely a type definition, not -type information (@pxref{String Field}) (that is, it need not start with -@samp{@var{type-number}=} if it is defining a new type). According to a -comment in GDB, this is also true of the type of the array elements; it -gives @samp{ar1;1;10;ar1;1;10;4} as a legitimate way to express a two -dimensional array. According to AIX documentation, the element type -must be type information. GDB accepts either. - -The type of the index is often a range type, expressed as the type -descriptor @samp{r} and some parameters. It defines the size of the -array. In the example below, the range @samp{r1;0;2;} defines an index -type which is a subrange of type 1 (integer), with a lower bound of 0 -and an upper bound of 2. This defines the valid range of subscripts of -a three-element C array. - -For example, the definition: - -@example -char char_vec[3] = @{'a','b','c'@}; -@end example - -@noindent -produces the output: - -@example -.stabs "char_vec:G19=ar1;0;2;2",32,0,0,0 - .global _char_vec - .align 4 -_char_vec: - .byte 97 - .byte 98 - .byte 99 -@end example - -If an array is @dfn{packed}, the elements are spaced more -closely than normal, saving memory at the expense of speed. For -example, an array of 3-byte objects might, if unpacked, have each -element aligned on a 4-byte boundary, but if packed, have no padding. -One way to specify that something is packed is with type attributes -(@pxref{String Field}). In the case of arrays, another is to use the -@samp{P} type descriptor instead of @samp{a}. Other than specifying a -packed array, @samp{P} is identical to @samp{a}. - -@c FIXME-what is it? A pointer? -An open array is represented by the @samp{A} type descriptor followed by -type information specifying the type of the array elements. - -@c FIXME: what is the format of this type? A pointer to a vector of pointers? -An N-dimensional dynamic array is represented by - -@example -D @var{dimensions} ; @var{type-information} -@end example - -@c Does dimensions really have this meaning? The AIX documentation -@c doesn't say. -@var{dimensions} is the number of dimensions; @var{type-information} -specifies the type of the array elements. - -@c FIXME: what is the format of this type? A pointer to some offsets in -@c another array? -A subarray of an N-dimensional array is represented by - -@example -E @var{dimensions} ; @var{type-information} -@end example - -@c Does dimensions really have this meaning? The AIX documentation -@c doesn't say. -@var{dimensions} is the number of dimensions; @var{type-information} -specifies the type of the array elements. - -@node Strings -@section Strings - -Some languages, like C or the original Pascal, do not have string types, -they just have related things like arrays of characters. But most -Pascals and various other languages have string types, which are -indicated as follows: - -@table @code -@item n @var{type-information} ; @var{bytes} -@var{bytes} is the maximum length. I'm not sure what -@var{type-information} is; I suspect that it means that this is a string -of @var{type-information} (thus allowing a string of integers, a string -of wide characters, etc., as well as a string of characters). Not sure -what the format of this type is. This is an AIX feature. - -@item z @var{type-information} ; @var{bytes} -Just like @samp{n} except that this is a gstring, not an ordinary -string. I don't know the difference. - -@item N -Pascal Stringptr. What is this? This is an AIX feature. -@end table - -Languages, such as CHILL which have a string type which is basically -just an array of characters use the @samp{S} type attribute -(@pxref{String Field}). - -@node Enumerations -@section Enumerations - -Enumerations are defined with the @samp{e} type descriptor. - -@c FIXME: Where does this information properly go? Perhaps it is -@c redundant with something we already explain. -The source line below declares an enumeration type at file scope. -The type definition is located after the @code{N_RBRAC} that marks the end of -the previous procedure's block scope, and before the @code{N_FUN} that marks -the beginning of the next procedure's block scope. Therefore it does not -describe a block local symbol, but a file local one. - -The source line: - -@example -enum e_places @{first,second=3,last@}; -@end example - -@noindent -generates the following stab: - -@example -.stabs "e_places:T22=efirst:0,second:3,last:4,;",128,0,0,0 -@end example - -The symbol descriptor (@samp{T}) says that the stab describes a -structure, enumeration, or union tag. The type descriptor @samp{e}, -following the @samp{22=} of the type definition narrows it down to an -enumeration type. Following the @samp{e} is a list of the elements of -the enumeration. The format is @samp{@var{name}:@var{value},}. The -list of elements ends with @samp{;}. The fact that @var{value} is -specified as an integer can cause problems if the value is large. GCC -2.5.2 tries to output it in octal in that case with a leading zero, -which is probably a good thing, although GDB 4.11 supports octal only in -cases where decimal is perfectly good. Negative decimal values are -supported by both GDB and dbx. - -There is no standard way to specify the size of an enumeration type; it -is determined by the architecture (normally all enumerations types are -32 bits). Type attributes can be used to specify an enumeration type of -another size for debuggers which support them; see @ref{String Field}. - -Enumeration types are unusual in that they define symbols for the -enumeration values (@code{first}, @code{second}, and @code{third} in the -above example), and even though these symbols are visible in the file as -a whole (rather than being in a more local namespace like structure -member names), they are defined in the type definition for the -enumeration type rather than each having their own symbol. In order to -be fast, GDB will only get symbols from such types (in its initial scan -of the stabs) if the type is the first thing defined after a @samp{T} or -@samp{t} symbol descriptor (the above example fulfills this -requirement). If the type does not have a name, the compiler should -emit it in a nameless stab (@pxref{String Field}); GCC does this. - -@node Structures -@section Structures - -The encoding of structures in stabs can be shown with an example. - -The following source code declares a structure tag and defines an -instance of the structure in global scope. Then a @code{typedef} equates the -structure tag with a new type. Seperate stabs are generated for the -structure tag, the structure @code{typedef}, and the structure instance. The -stabs for the tag and the @code{typedef} are emited when the definitions are -encountered. Since the structure elements are not initialized, the -stab and code for the structure variable itself is located at the end -of the program in the bss section. - -@example -struct s_tag @{ - int s_int; - float s_float; - char s_char_vec[8]; - struct s_tag* s_next; -@} g_an_s; - -typedef struct s_tag s_typedef; -@end example - -The structure tag has an @code{N_LSYM} stab type because, like the -enumeration, the symbol has file scope. Like the enumeration, the -symbol descriptor is @samp{T}, for enumeration, structure, or tag type. -The type descriptor @samp{s} following the @samp{16=} of the type -definition narrows the symbol type to structure. - -Following the @samp{s} type descriptor is the number of bytes the -structure occupies, followed by a description of each structure element. -The structure element descriptions are of the form @var{name:type, bit -offset from the start of the struct, number of bits in the element}. - -@c FIXME: phony line break. Can probably be fixed by using an example -@c with fewer fields. -@example -# @r{128 is N_LSYM} -.stabs "s_tag:T16=s20s_int:1,0,32;s_float:12,32,32; - s_char_vec:17=ar1;0;7;2,64,64;s_next:18=*16,128,32;;",128,0,0,0 -@end example - -In this example, the first two structure elements are previously defined -types. For these, the type following the @samp{@var{name}:} part of the -element description is a simple type reference. The other two structure -elements are new types. In this case there is a type definition -embedded after the @samp{@var{name}:}. The type definition for the -array element looks just like a type definition for a standalone array. -The @code{s_next} field is a pointer to the same kind of structure that -the field is an element of. So the definition of structure type 16 -contains a type definition for an element which is a pointer to type 16. - -If a field is a static member (this is a C++ feature in which a single -variable appears to be a field of every structure of a given type) it -still starts out with the field name, a colon, and the type, but then -instead of a comma, bit position, comma, and bit size, there is a colon -followed by the name of the variable which each such field refers to. - -If the structure has methods (a C++ feature), they follow the non-method -fields; see @ref{Cplusplus}. - -@node Typedefs -@section Giving a Type a Name - -To give a type a name, use the @samp{t} symbol descriptor. The type -is specified by the type information (@pxref{String Field}) for the stab. -For example, - -@example -.stabs "s_typedef:t16",128,0,0,0 # @r{128 is N_LSYM} -@end example - -specifies that @code{s_typedef} refers to type number 16. Such stabs -have symbol type @code{N_LSYM} (or @code{C_DECL} for XCOFF). - -If you are specifying the tag name for a structure, union, or -enumeration, use the @samp{T} symbol descriptor instead. I believe C is -the only language with this feature. - -If the type is an opaque type (I believe this is a Modula-2 feature), -AIX provides a type descriptor to specify it. The type descriptor is -@samp{o} and is followed by a name. I don't know what the name -means---is it always the same as the name of the type, or is this type -descriptor used with a nameless stab (@pxref{String Field})? There -optionally follows a comma followed by type information which defines -the type of this type. If omitted, a semicolon is used in place of the -comma and the type information, and the type is much like a generic -pointer type---it has a known size but little else about it is -specified. - -@node Unions -@section Unions - -@example -union u_tag @{ - int u_int; - float u_float; - char* u_char; -@} an_u; -@end example - -This code generates a stab for a union tag and a stab for a union -variable. Both use the @code{N_LSYM} stab type. If a union variable is -scoped locally to the procedure in which it is defined, its stab is -located immediately preceding the @code{N_LBRAC} for the procedure's block -start. - -The stab for the union tag, however, is located preceding the code for -the procedure in which it is defined. The stab type is @code{N_LSYM}. This -would seem to imply that the union type is file scope, like the struct -type @code{s_tag}. This is not true. The contents and position of the stab -for @code{u_type} do not convey any infomation about its procedure local -scope. - -@c FIXME: phony line break. Can probably be fixed by using an example -@c with fewer fields. -@smallexample -# @r{128 is N_LSYM} -.stabs "u_tag:T23=u4u_int:1,0,32;u_float:12,0,32;u_char:21,0,32;;", - 128,0,0,0 -@end smallexample - -The symbol descriptor @samp{T}, following the @samp{name:} means that -the stab describes an enumeration, structure, or union tag. The type -descriptor @samp{u}, following the @samp{23=} of the type definition, -narrows it down to a union type definition. Following the @samp{u} is -the number of bytes in the union. After that is a list of union element -descriptions. Their format is @var{name:type, bit offset into the -union, number of bytes for the element;}. - -The stab for the union variable is: - -@example -.stabs "an_u:23",128,0,0,-20 # @r{128 is N_LSYM} -@end example - -@samp{-20} specifies where the variable is stored (@pxref{Stack -Variables}). - -@node Function Types -@section Function Types - -Various types can be defined for function variables. These types are -not used in defining functions (@pxref{Procedures}); they are used for -things like pointers to functions. - -The simple, traditional, type is type descriptor @samp{f} is followed by -type information for the return type of the function, followed by a -semicolon. - -This does not deal with functions for which the number and types of the -parameters are part of the type, as in Modula-2 or ANSI C. AIX provides -extensions to specify these, using the @samp{f}, @samp{F}, @samp{p}, and -@samp{R} type descriptors. - -First comes the type descriptor. If it is @samp{f} or @samp{F}, this -type involves a function rather than a procedure, and the type -information for the return type of the function follows, followed by a -comma. Then comes the number of parameters to the function and a -semicolon. Then, for each parameter, there is the name of the parameter -followed by a colon (this is only present for type descriptors @samp{R} -and @samp{F} which represent Pascal function or procedure parameters), -type information for the parameter, a comma, 0 if passed by reference or -1 if passed by value, and a semicolon. The type definition ends with a -semicolon. - -For example, this variable definition: - -@example -int (*g_pf)(); -@end example - -@noindent -generates the following code: - -@example -.stabs "g_pf:G24=*25=f1",32,0,0,0 - .common _g_pf,4,"bss" -@end example - -The variable defines a new type, 24, which is a pointer to another new -type, 25, which is a function returning @code{int}. - -@node Symbol Tables -@chapter Symbol Information in Symbol Tables - -This chapter describes the format of symbol table entries -and how stab assembler directives map to them. It also describes the -transformations that the assembler and linker make on data from stabs. - -@menu -* Symbol Table Format:: -* Transformations On Symbol Tables:: -@end menu - -@node Symbol Table Format -@section Symbol Table Format - -Each time the assembler encounters a stab directive, it puts -each field of the stab into a corresponding field in a symbol table -entry of its output file. If the stab contains a string field, the -symbol table entry for that stab points to a string table entry -containing the string data from the stab. Assembler labels become -relocatable addresses. Symbol table entries in a.out have the format: - -@c FIXME: should refer to external, not internal. -@example -struct internal_nlist @{ - unsigned long n_strx; /* index into string table of name */ - unsigned char n_type; /* type of symbol */ - unsigned char n_other; /* misc info (usually empty) */ - unsigned short n_desc; /* description field */ - bfd_vma n_value; /* value of symbol */ -@}; -@end example - -If the stab has a string, the @code{n_strx} field holds the offset in -bytes of the string within the string table. The string is terminated -by a NUL character. If the stab lacks a string (for example, it was -produced by a @code{.stabn} or @code{.stabd} directive), the -@code{n_strx} field is zero. - -Symbol table entries with @code{n_type} field values greater than 0x1f -originated as stabs generated by the compiler (with one random -exception). The other entries were placed in the symbol table of the -executable by the assembler or the linker. - -@node Transformations On Symbol Tables -@section Transformations on Symbol Tables - -The linker concatenates object files and does fixups of externally -defined symbols. - -You can see the transformations made on stab data by the assembler and -linker by examining the symbol table after each pass of the build. To -do this, use @samp{nm -ap}, which dumps the symbol table, including -debugging information, unsorted. For stab entries the columns are: -@var{value}, @var{other}, @var{desc}, @var{type}, @var{string}. For -assembler and linker symbols, the columns are: @var{value}, @var{type}, -@var{string}. - -The low 5 bits of the stab type tell the linker how to relocate the -value of the stab. Thus for stab types like @code{N_RSYM} and -@code{N_LSYM}, where the value is an offset or a register number, the -low 5 bits are @code{N_ABS}, which tells the linker not to relocate the -value. - -Where the value of a stab contains an assembly language label, -it is transformed by each build step. The assembler turns it into a -relocatable address and the linker turns it into an absolute address. - -@menu -* Transformations On Static Variables:: -* Transformations On Global Variables:: -* Stab Section Transformations:: For some object file formats, - things are a bit different. -@end menu - -@node Transformations On Static Variables -@subsection Transformations on Static Variables - -This source line defines a static variable at file scope: - -@example -static int s_g_repeat -@end example - -@noindent -The following stab describes the symbol: - -@example -.stabs "s_g_repeat:S1",38,0,0,_s_g_repeat -@end example - -@noindent -The assembler transforms the stab into this symbol table entry in the -@file{.o} file. The location is expressed as a data segment offset. - -@example -00000084 - 00 0000 STSYM s_g_repeat:S1 -@end example - -@noindent -In the symbol table entry from the executable, the linker has made the -relocatable address absolute. - -@example -0000e00c - 00 0000 STSYM s_g_repeat:S1 -@end example - -@node Transformations On Global Variables -@subsection Transformations on Global Variables - -Stabs for global variables do not contain location information. In -this case, the debugger finds location information in the assembler or -linker symbol table entry describing the variable. The source line: - -@example -char g_foo = 'c'; -@end example - -@noindent -generates the stab: - -@example -.stabs "g_foo:G2",32,0,0,0 -@end example - -The variable is represented by two symbol table entries in the object -file (see below). The first one originated as a stab. The second one -is an external symbol. The upper case @samp{D} signifies that the -@code{n_type} field of the symbol table contains 7, @code{N_DATA} with -local linkage. The stab's value is zero since the value is not used for -@code{N_GSYM} stabs. The value of the linker symbol is the relocatable -address corresponding to the variable. - -@example -00000000 - 00 0000 GSYM g_foo:G2 -00000080 D _g_foo -@end example - -@noindent -These entries as transformed by the linker. The linker symbol table -entry now holds an absolute address: - -@example -00000000 - 00 0000 GSYM g_foo:G2 -@dots{} -0000e008 D _g_foo -@end example - -@node Stab Section Transformations -@subsection Transformations of Stabs in separate sections - -For object file formats using stabs in separate sections (@pxref{Stab -Sections}), use @code{objdump --stabs} instead of @code{nm} to show the -stabs in an object or executable file. @code{objdump} is a GNU utility; -Sun does not provide any equivalent. - -The following example is for a stab whose value is an address is -relative to the compilation unit (@pxref{ELF Linker Relocation}). For -example, if the source line - -@example -static int ld = 5; -@end example - -appears within a function, then the assembly language output from the -compiler contains: - -@example -.Ddata.data: -@dots{} - .stabs "ld:V(0,3)",0x26,0,4,.L18-Ddata.data # @r{0x26 is N_STSYM} -@dots{} -.L18: - .align 4 - .word 0x5 -@end example - -Because the value is formed by subtracting one symbol from another, the -value is absolute, not relocatable, and so the object file contains - -@example -Symnum n_type n_othr n_desc n_value n_strx String -31 STSYM 0 4 00000004 680 ld:V(0,3) -@end example - -without any relocations, and the executable file also contains - -@example -Symnum n_type n_othr n_desc n_value n_strx String -31 STSYM 0 4 00000004 680 ld:V(0,3) -@end example - -@node Cplusplus -@chapter GNU C++ Stabs - -@menu -* Class Names:: C++ class names are both tags and typedefs. -* Nested Symbols:: C++ symbol names can be within other types. -* Basic Cplusplus Types:: -* Simple Classes:: -* Class Instance:: -* Methods:: Method definition -* Method Type Descriptor:: The @samp{#} type descriptor -* Member Type Descriptor:: The @samp{@@} type descriptor -* Protections:: -* Method Modifiers:: -* Virtual Methods:: -* Inheritence:: -* Virtual Base Classes:: -* Static Members:: -@end menu - -@node Class Names -@section C++ Class Names - -In C++, a class name which is declared with @code{class}, @code{struct}, -or @code{union}, is not only a tag, as in C, but also a type name. Thus -there should be stabs with both @samp{t} and @samp{T} symbol descriptors -(@pxref{Typedefs}). - -To save space, there is a special abbreviation for this case. If the -@samp{T} symbol descriptor is followed by @samp{t}, then the stab -defines both a type name and a tag. - -For example, the C++ code - -@example -struct foo @{int x;@}; -@end example - -can be represented as either - -@example -.stabs "foo:T19=s4x:1,0,32;;",128,0,0,0 # @r{128 is N_LSYM} -.stabs "foo:t19",128,0,0,0 -@end example - -or - -@example -.stabs "foo:Tt19=s4x:1,0,32;;",128,0,0,0 -@end example - -@node Nested Symbols -@section Defining a Symbol Within Another Type - -In C++, a symbol (such as a type name) can be defined within another type. -@c FIXME: Needs example. - -In stabs, this is sometimes represented by making the name of a symbol -which contains @samp{::}. Such a pair of colons does not end the name -of the symbol, the way a single colon would (@pxref{String Field}). I'm -not sure how consistently used or well thought out this mechanism is. -So that a pair of colons in this position always has this meaning, -@samp{:} cannot be used as a symbol descriptor. - -For example, if the string for a stab is @samp{foo::bar::baz:t5=*6}, -then @code{foo::bar::baz} is the name of the symbol, @samp{t} is the -symbol descriptor, and @samp{5=*6} is the type information. - -@node Basic Cplusplus Types -@section Basic Types For C++ - -<< the examples that follow are based on a01.C >> - - -C++ adds two more builtin types to the set defined for C. These are -the unknown type and the vtable record type. The unknown type, type -16, is defined in terms of itself like the void type. - -The vtable record type, type 17, is defined as a structure type and -then as a structure tag. The structure has four fields: delta, index, -pfn, and delta2. pfn is the function pointer. - -<< In boilerplate $vtbl_ptr_type, what are the fields delta, -index, and delta2 used for? >> - -This basic type is present in all C++ programs even if there are no -virtual methods defined. - -@display -.stabs "struct_name:sym_desc(type)type_def(17)=type_desc(struct)struct_bytes(8) - elem_name(delta):type_ref(short int),bit_offset(0),field_bits(16); - elem_name(index):type_ref(short int),bit_offset(16),field_bits(16); - elem_name(pfn):type_def(18)=type_desc(ptr to)type_ref(void), - bit_offset(32),field_bits(32); - elem_name(delta2):type_def(short int);bit_offset(32),field_bits(16);;" - N_LSYM, NIL, NIL -@end display - -@smallexample -.stabs "$vtbl_ptr_type:t17=s8 - delta:6,0,16;index:6,16,16;pfn:18=*15,32,32;delta2:6,32,16;;" - ,128,0,0,0 -@end smallexample - -@display -.stabs "name:sym_dec(struct tag)type_ref($vtbl_ptr_type)",N_LSYM,NIL,NIL,NIL -@end display - -@example -.stabs "$vtbl_ptr_type:T17",128,0,0,0 -@end example - -@node Simple Classes -@section Simple Class Definition - -The stabs describing C++ language features are an extension of the -stabs describing C. Stabs representing C++ class types elaborate -extensively on the stab format used to describe structure types in C. -Stabs representing class type variables look just like stabs -representing C language variables. - -Consider the following very simple class definition. - -@example -class baseA @{ -public: - int Adat; - int Ameth(int in, char other); -@}; -@end example - -The class @code{baseA} is represented by two stabs. The first stab describes -the class as a structure type. The second stab describes a structure -tag of the class type. Both stabs are of stab type @code{N_LSYM}. Since the -stab is not located between an @code{N_FUN} and an @code{N_LBRAC} stab this indicates -that the class is defined at file scope. If it were, then the @code{N_LSYM} -would signify a local variable. - -A stab describing a C++ class type is similar in format to a stab -describing a C struct, with each class member shown as a field in the -structure. The part of the struct format describing fields is -expanded to include extra information relevent to C++ class members. -In addition, if the class has multiple base classes or virtual -functions the struct format outside of the field parts is also -augmented. - -In this simple example the field part of the C++ class stab -representing member data looks just like the field part of a C struct -stab. The section on protections describes how its format is -sometimes extended for member data. - -The field part of a C++ class stab representing a member function -differs substantially from the field part of a C struct stab. It -still begins with @samp{name:} but then goes on to define a new type number -for the member function, describe its return type, its argument types, -its protection level, any qualifiers applied to the method definition, -and whether the method is virtual or not. If the method is virtual -then the method description goes on to give the vtable index of the -method, and the type number of the first base class defining the -method. - -When the field name is a method name it is followed by two colons rather -than one. This is followed by a new type definition for the method. -This is a number followed by an equal sign and the type of the method. -Normally this will be a type declared using the @samp{#} type -descriptor; see @ref{Method Type Descriptor}; static member functions -are declared using the @samp{f} type descriptor instead; see -@ref{Function Types}. - -The format of an overloaded operator method name differs from that of -other methods. It is @samp{op$::@var{operator-name}.} where -@var{operator-name} is the operator name such as @samp{+} or @samp{+=}. -The name ends with a period, and any characters except the period can -occur in the @var{operator-name} string. - -The next part of the method description represents the arguments to the -method, preceeded by a colon and ending with a semi-colon. The types of -the arguments are expressed in the same way argument types are expressed -in C++ name mangling. In this example an @code{int} and a @code{char} -map to @samp{ic}. - -This is followed by a number, a letter, and an asterisk or period, -followed by another semicolon. The number indicates the protections -that apply to the member function. Here the 2 means public. The -letter encodes any qualifier applied to the method definition. In -this case, @samp{A} means that it is a normal function definition. The dot -shows that the method is not virtual. The sections that follow -elaborate further on these fields and describe the additional -information present for virtual methods. - - -@display -.stabs "class_name:sym_desc(type)type_def(20)=type_desc(struct)struct_bytes(4) - field_name(Adat):type(int),bit_offset(0),field_bits(32); - - method_name(Ameth)::type_def(21)=type_desc(method)return_type(int); - :arg_types(int char); - protection(public)qualifier(normal)virtual(no);;" - N_LSYM,NIL,NIL,NIL -@end display - -@smallexample -.stabs "baseA:t20=s4Adat:1,0,32;Ameth::21=##1;:ic;2A.;;",128,0,0,0 - -.stabs "class_name:sym_desc(struct tag)",N_LSYM,NIL,NIL,NIL - -.stabs "baseA:T20",128,0,0,0 -@end smallexample - -@node Class Instance -@section Class Instance - -As shown above, describing even a simple C++ class definition is -accomplished by massively extending the stab format used in C to -describe structure types. However, once the class is defined, C stabs -with no modifications can be used to describe class instances. The -following source: - -@example -main () @{ - baseA AbaseA; -@} -@end example - -@noindent -yields the following stab describing the class instance. It looks no -different from a standard C stab describing a local variable. - -@display -.stabs "name:type_ref(baseA)", N_LSYM, NIL, NIL, frame_ptr_offset -@end display - -@example -.stabs "AbaseA:20",128,0,0,-20 -@end example - -@node Methods -@section Method Definition - -The class definition shown above declares Ameth. The C++ source below -defines Ameth: - -@example -int -baseA::Ameth(int in, char other) -@{ - return in; -@}; -@end example - - -This method definition yields three stabs following the code of the -method. One stab describes the method itself and following two describe -its parameters. Although there is only one formal argument all methods -have an implicit argument which is the @code{this} pointer. The @code{this} -pointer is a pointer to the object on which the method was called. Note -that the method name is mangled to encode the class name and argument -types. Name mangling is described in the @sc{arm} (@cite{The Annotated -C++ Reference Manual}, by Ellis and Stroustrup, @sc{isbn} -0-201-51459-1); @file{gpcompare.texi} in Cygnus GCC distributions -describes the differences between GNU mangling and @sc{arm} -mangling. -@c FIXME: Use @xref, especially if this is generally installed in the -@c info tree. -@c FIXME: This information should be in a net release, either of GCC or -@c GDB. But gpcompare.texi doesn't seem to be in the FSF GCC. - -@example -.stabs "name:symbol_desriptor(global function)return_type(int)", - N_FUN, NIL, NIL, code_addr_of_method_start - -.stabs "Ameth__5baseAic:F1",36,0,0,_Ameth__5baseAic -@end example - -Here is the stab for the @code{this} pointer implicit argument. The -name of the @code{this} pointer is always @code{this}. Type 19, the -@code{this} pointer is defined as a pointer to type 20, @code{baseA}, -but a stab defining @code{baseA} has not yet been emited. Since the -compiler knows it will be emited shortly, here it just outputs a cross -reference to the undefined symbol, by prefixing the symbol name with -@samp{xs}. - -@example -.stabs "name:sym_desc(register param)type_def(19)= - type_desc(ptr to)type_ref(baseA)= - type_desc(cross-reference to)baseA:",N_RSYM,NIL,NIL,register_number - -.stabs "this:P19=*20=xsbaseA:",64,0,0,8 -@end example - -The stab for the explicit integer argument looks just like a parameter -to a C function. The last field of the stab is the offset from the -argument pointer, which in most systems is the same as the frame -pointer. - -@example -.stabs "name:sym_desc(value parameter)type_ref(int)", - N_PSYM,NIL,NIL,offset_from_arg_ptr - -.stabs "in:p1",160,0,0,72 -@end example - -<< The examples that follow are based on A1.C >> - -@node Method Type Descriptor -@section The @samp{#} Type Descriptor - -This is like the @samp{f} type descriptor for functions (@pxref{Function -Types}), except that a function which uses the @samp{#} type descriptor -takes an extra argument as its first argument, for the @code{this} -pointer. The @samp{#} type descriptor is optionally followed by the -types of the arguments, then another @samp{#}. If the types of the -arguments are omitted, so that the second @samp{#} immediately follows -the @samp{#} which is the type descriptor, the arguments are being -omitted (to save space) and can be deduced from the mangled name of the -method. After the second @samp{#} there is type information for the -return type of the method and a semicolon. - -Note that although such a type will normally be used to describe fields -in structures, unions, or classes, for at least some versions of the -compiler it can also be used in other contexts. - -@node Member Type Descriptor -@section The @samp{@@} Type Descriptor - -The @samp{@@} type descriptor is for a member (class and variable) type. -It is followed by type information for the offset basetype, a comma, and -type information for the type of the field being pointed to. (FIXME: -this is acknowledged to be gibberish. Can anyone say what really goes -here?). - -Note that there is a conflict between this and type attributes -(@pxref{String Field}); both use type descriptor @samp{@@}. -Fortunately, the @samp{@@} type descriptor used in this C++ sense always -will be followed by a digit, @samp{(}, or @samp{-}, and type attributes -never start with those things. - -@node Protections -@section Protections - -In the simple class definition shown above all member data and -functions were publicly accessable. The example that follows -contrasts public, protected and privately accessable fields and shows -how these protections are encoded in C++ stabs. - -If the character following the @samp{@var{field-name}:} part of the -string is @samp{/}, then the next character is the visibility. @samp{0} -means private, @samp{1} means protected, and @samp{2} means public. -Debuggers should ignore visibility characters they do not recognize, and -assume a reasonable default (such as public) (GDB 4.11 does not, but -this should be fixed in the next GDB release). If no visibility is -specified the field is public. The visibility @samp{9} means that the -field has been optimized out and is public (there is no way to specify -an optimized out field with a private or protected visibility). -Visibility @samp{9} is not supported by GDB 4.11; this should be fixed -in the next GDB release. - -The following C++ source: - -@example -class vis @{ -private: - int priv; -protected: - char prot; -public: - float pub; -@}; -@end example - -@noindent -generates the following stab: - -@example -# @r{128 is N_LSYM} -.stabs "vis:T19=s12priv:/01,0,32;prot:/12,32,8;pub:12,64,32;;",128,0,0,0 -@end example - -@samp{vis:T19=s12} indicates that type number 19 is a 12 byte structure -named @code{vis} The @code{priv} field has public visibility -(@samp{/0}), type int (@samp{1}), and offset and size @samp{,0,32;}. -The @code{prot} field has protected visibility (@samp{/1}), type char -(@samp{2}) and offset and size @samp{,32,8;}. The @code{pub} field has -type float (@samp{12}), and offset and size @samp{,64,32;}. - -Protections for member functions are signified by one digit embeded in -the field part of the stab describing the method. The digit is 0 if -private, 1 if protected and 2 if public. Consider the C++ class -definition below: - -@example -class all_methods @{ -private: - int priv_meth(int in)@{return in;@}; -protected: - char protMeth(char in)@{return in;@}; -public: - float pubMeth(float in)@{return in;@}; -@}; -@end example - -It generates the following stab. The digit in question is to the left -of an @samp{A} in each case. Notice also that in this case two symbol -descriptors apply to the class name struct tag and struct type. - -@display -.stabs "class_name:sym_desc(struct tag&type)type_def(21)= - sym_desc(struct)struct_bytes(1) - meth_name::type_def(22)=sym_desc(method)returning(int); - :args(int);protection(private)modifier(normal)virtual(no); - meth_name::type_def(23)=sym_desc(method)returning(char); - :args(char);protection(protected)modifier(normal)virual(no); - meth_name::type_def(24)=sym_desc(method)returning(float); - :args(float);protection(public)modifier(normal)virtual(no);;", - N_LSYM,NIL,NIL,NIL -@end display - -@smallexample -.stabs "all_methods:Tt21=s1priv_meth::22=##1;:i;0A.;protMeth::23=##2;:c;1A.; - pubMeth::24=##12;:f;2A.;;",128,0,0,0 -@end smallexample - -@node Method Modifiers -@section Method Modifiers (@code{const}, @code{volatile}, @code{const volatile}) - -<< based on a6.C >> - -In the class example described above all the methods have the normal -modifier. This method modifier information is located just after the -protection information for the method. This field has four possible -character values. Normal methods use @samp{A}, const methods use -@samp{B}, volatile methods use @samp{C}, and const volatile methods use -@samp{D}. Consider the class definition below: - -@example -class A @{ -public: - int ConstMeth (int arg) const @{ return arg; @}; - char VolatileMeth (char arg) volatile @{ return arg; @}; - float ConstVolMeth (float arg) const volatile @{return arg; @}; -@}; -@end example - -This class is described by the following stab: - -@display -.stabs "class(A):sym_desc(struct)type_def(20)=type_desc(struct)struct_bytes(1) - meth_name(ConstMeth)::type_def(21)sym_desc(method) - returning(int);:arg(int);protection(public)modifier(const)virtual(no); - meth_name(VolatileMeth)::type_def(22)=sym_desc(method) - returning(char);:arg(char);protection(public)modifier(volatile)virt(no) - meth_name(ConstVolMeth)::type_def(23)=sym_desc(method) - returning(float);:arg(float);protection(public)modifer(const volatile) - virtual(no);;", @dots{} -@end display - -@example -.stabs "A:T20=s1ConstMeth::21=##1;:i;2B.;VolatileMeth::22=##2;:c;2C.; - ConstVolMeth::23=##12;:f;2D.;;",128,0,0,0 -@end example - -@node Virtual Methods -@section Virtual Methods - -<< The following examples are based on a4.C >> - -The presence of virtual methods in a class definition adds additional -data to the class description. The extra data is appended to the -description of the virtual method and to the end of the class -description. Consider the class definition below: - -@example -class A @{ -public: - int Adat; - virtual int A_virt (int arg) @{ return arg; @}; -@}; -@end example - -This results in the stab below describing class A. It defines a new -type (20) which is an 8 byte structure. The first field of the class -struct is @samp{Adat}, an integer, starting at structure offset 0 and -occupying 32 bits. - -The second field in the class struct is not explicitly defined by the -C++ class definition but is implied by the fact that the class -contains a virtual method. This field is the vtable pointer. The -name of the vtable pointer field starts with @samp{$vf} and continues with a -type reference to the class it is part of. In this example the type -reference for class A is 20 so the name of its vtable pointer field is -@samp{$vf20}, followed by the usual colon. - -Next there is a type definition for the vtable pointer type (21). -This is in turn defined as a pointer to another new type (22). - -Type 22 is the vtable itself, which is defined as an array, indexed by -a range of integers between 0 and 1, and whose elements are of type -17. Type 17 was the vtable record type defined by the boilerplate C++ -type definitions, as shown earlier. - -The bit offset of the vtable pointer field is 32. The number of bits -in the field are not specified when the field is a vtable pointer. - -Next is the method definition for the virtual member function @code{A_virt}. -Its description starts out using the same format as the non-virtual -member functions described above, except instead of a dot after the -@samp{A} there is an asterisk, indicating that the function is virtual. -Since is is virtual some addition information is appended to the end -of the method description. - -The first number represents the vtable index of the method. This is a -32 bit unsigned number with the high bit set, followed by a -semi-colon. - -The second number is a type reference to the first base class in the -inheritence hierarchy defining the virtual member function. In this -case the class stab describes a base class so the virtual function is -not overriding any other definition of the method. Therefore the -reference is to the type number of the class that the stab is -describing (20). - -This is followed by three semi-colons. One marks the end of the -current sub-section, one marks the end of the method field, and the -third marks the end of the struct definition. - -For classes containing virtual functions the very last section of the -string part of the stab holds a type reference to the first base -class. This is preceeded by @samp{~%} and followed by a final semi-colon. - -@display -.stabs "class_name(A):type_def(20)=sym_desc(struct)struct_bytes(8) - field_name(Adat):type_ref(int),bit_offset(0),field_bits(32); - field_name(A virt func ptr):type_def(21)=type_desc(ptr to)type_def(22)= - sym_desc(array)index_type_ref(range of int from 0 to 1); - elem_type_ref(vtbl elem type), - bit_offset(32); - meth_name(A_virt)::typedef(23)=sym_desc(method)returning(int); - :arg_type(int),protection(public)normal(yes)virtual(yes) - vtable_index(1);class_first_defining(A);;;~%first_base(A);", - N_LSYM,NIL,NIL,NIL -@end display - -@c FIXME: bogus line break. -@example -.stabs "A:t20=s8Adat:1,0,32;$vf20:21=*22=ar1;0;1;17,32; - A_virt::23=##1;:i;2A*-2147483647;20;;;~%20;",128,0,0,0 -@end example - -@node Inheritence -@section Inheritence - -Stabs describing C++ derived classes include additional sections that -describe the inheritence hierarchy of the class. A derived class stab -also encodes the number of base classes. For each base class it tells -if the base class is virtual or not, and if the inheritence is private -or public. It also gives the offset into the object of the portion of -the object corresponding to each base class. - -This additional information is embeded in the class stab following the -number of bytes in the struct. First the number of base classes -appears bracketed by an exclamation point and a comma. - -Then for each base type there repeats a series: a virtual character, a -visibilty character, a number, a comma, another number, and a -semi-colon. - -The virtual character is @samp{1} if the base class is virtual and -@samp{0} if not. The visibility character is @samp{2} if the derivation -is public, @samp{1} if it is protected, and @samp{0} if it is private. -Debuggers should ignore virtual or visibility characters they do not -recognize, and assume a reasonable default (such as public and -non-virtual) (GDB 4.11 does not, but this should be fixed in the next -GDB release). - -The number following the virtual and visibility characters is the offset -from the start of the object to the part of the object pertaining to the -base class. - -After the comma, the second number is a type_descriptor for the base -type. Finally a semi-colon ends the series, which repeats for each -base class. - -The source below defines three base classes @code{A}, @code{B}, and -@code{C} and the derived class @code{D}. - - -@example -class A @{ -public: - int Adat; - virtual int A_virt (int arg) @{ return arg; @}; -@}; - -class B @{ -public: - int B_dat; - virtual int B_virt (int arg) @{return arg; @}; -@}; - -class C @{ -public: - int Cdat; - virtual int C_virt (int arg) @{return arg; @}; -@}; - -class D : A, virtual B, public C @{ -public: - int Ddat; - virtual int A_virt (int arg ) @{ return arg+1; @}; - virtual int B_virt (int arg) @{ return arg+2; @}; - virtual int C_virt (int arg) @{ return arg+3; @}; - virtual int D_virt (int arg) @{ return arg; @}; -@}; -@end example - -Class stabs similar to the ones described earlier are generated for -each base class. - -@c FIXME!!! the linebreaks in the following example probably make the -@c examples literally unusable, but I don't know any other way to get -@c them on the page. -@c One solution would be to put some of the type definitions into -@c separate stabs, even if that's not exactly what the compiler actually -@c emits. -@smallexample -.stabs "A:T20=s8Adat:1,0,32;$vf20:21=*22=ar1;0;1;17,32; - A_virt::23=##1;:i;2A*-2147483647;20;;;~%20;",128,0,0,0 - -.stabs "B:Tt25=s8Bdat:1,0,32;$vf25:21,32;B_virt::26=##1; - :i;2A*-2147483647;25;;;~%25;",128,0,0,0 - -.stabs "C:Tt28=s8Cdat:1,0,32;$vf28:21,32;C_virt::29=##1; - :i;2A*-2147483647;28;;;~%28;",128,0,0,0 -@end smallexample - -In the stab describing derived class @code{D} below, the information about -the derivation of this class is encoded as follows. - -@display -.stabs "derived_class_name:symbol_descriptors(struct tag&type)= - type_descriptor(struct)struct_bytes(32)!num_bases(3), - base_virtual(no)inheritence_public(no)base_offset(0), - base_class_type_ref(A); - base_virtual(yes)inheritence_public(no)base_offset(NIL), - base_class_type_ref(B); - base_virtual(no)inheritence_public(yes)base_offset(64), - base_class_type_ref(C); @dots{} -@end display - -@c FIXME! fake linebreaks. -@smallexample -.stabs "D:Tt31=s32!3,000,20;100,25;0264,28;$vb25:24,128;Ddat: - 1,160,32;A_virt::32=##1;:i;2A*-2147483647;20;;B_virt: - :32:i;2A*-2147483647;25;;C_virt::32:i;2A*-2147483647; - 28;;D_virt::32:i;2A*-2147483646;31;;;~%20;",128,0,0,0 -@end smallexample - -@node Virtual Base Classes -@section Virtual Base Classes - -A derived class object consists of a concatination in memory of the data -areas defined by each base class, starting with the leftmost and ending -with the rightmost in the list of base classes. The exception to this -rule is for virtual inheritence. In the example above, class @code{D} -inherits virtually from base class @code{B}. This means that an -instance of a @code{D} object will not contain its own @code{B} part but -merely a pointer to a @code{B} part, known as a virtual base pointer. - -In a derived class stab, the base offset part of the derivation -information, described above, shows how the base class parts are -ordered. The base offset for a virtual base class is always given as 0. -Notice that the base offset for @code{B} is given as 0 even though -@code{B} is not the first base class. The first base class @code{A} -starts at offset 0. - -The field information part of the stab for class @code{D} describes the field -which is the pointer to the virtual base class @code{B}. The vbase pointer -name is @samp{$vb} followed by a type reference to the virtual base class. -Since the type id for @code{B} in this example is 25, the vbase pointer name -is @samp{$vb25}. - -@c FIXME!! fake linebreaks below -@smallexample -.stabs "D:Tt31=s32!3,000,20;100,25;0264,28;$vb25:24,128;Ddat:1, - 160,32;A_virt::32=##1;:i;2A*-2147483647;20;;B_virt::32:i; - 2A*-2147483647;25;;C_virt::32:i;2A*-2147483647;28;;D_virt: - :32:i;2A*-2147483646;31;;;~%20;",128,0,0,0 -@end smallexample - -Following the name and a semicolon is a type reference describing the -type of the virtual base class pointer, in this case 24. Type 24 was -defined earlier as the type of the @code{B} class @code{this} pointer. The -@code{this} pointer for a class is a pointer to the class type. - -@example -.stabs "this:P24=*25=xsB:",64,0,0,8 -@end example - -Finally the field offset part of the vbase pointer field description -shows that the vbase pointer is the first field in the @code{D} object, -before any data fields defined by the class. The layout of a @code{D} -class object is a follows, @code{Adat} at 0, the vtable pointer for -@code{A} at 32, @code{Cdat} at 64, the vtable pointer for C at 96, the -virtual base pointer for @code{B} at 128, and @code{Ddat} at 160. - - -@node Static Members -@section Static Members - -The data area for a class is a concatenation of the space used by the -data members of the class. If the class has virtual methods, a vtable -pointer follows the class data. The field offset part of each field -description in the class stab shows this ordering. - -<< How is this reflected in stabs? See Cygnus bug #677 for some info. >> - -@node Stab Types -@appendix Table of Stab Types - -The following are all the possible values for the stab type field, for -a.out files, in numeric order. This does not apply to XCOFF, but -it does apply to stabs in sections (@pxref{Stab Sections}). Stabs in -ECOFF use these values but add 0x8f300 to distinguish them from non-stab -symbols. - -The symbolic names are defined in the file @file{include/aout/stabs.def}. - -@menu -* Non-Stab Symbol Types:: Types from 0 to 0x1f -* Stab Symbol Types:: Types from 0x20 to 0xff -@end menu - -@node Non-Stab Symbol Types -@appendixsec Non-Stab Symbol Types - -The following types are used by the linker and assembler, not by stab -directives. Since this document does not attempt to describe aspects of -object file format other than the debugging format, no details are -given. - -@c Try to get most of these to fit on a single line. -@iftex -@tableindent=1.5in -@end iftex - -@table @code -@item 0x0 N_UNDF -Undefined symbol - -@item 0x2 N_ABS -File scope absolute symbol - -@item 0x3 N_ABS | N_EXT -External absolute symbol - -@item 0x4 N_TEXT -File scope text symbol - -@item 0x5 N_TEXT | N_EXT -External text symbol - -@item 0x6 N_DATA -File scope data symbol - -@item 0x7 N_DATA | N_EXT -External data symbol - -@item 0x8 N_BSS -File scope BSS symbol - -@item 0x9 N_BSS | N_EXT -External BSS symbol - -@item 0x0c N_FN_SEQ -Same as @code{N_FN}, for Sequent compilers - -@item 0x0a N_INDR -Symbol is indirected to another symbol - -@item 0x12 N_COMM -Common---visible after shared library dynamic link - -@item 0x14 N_SETA -@itemx 0x15 N_SETA | N_EXT -Absolute set element - -@item 0x16 N_SETT -@itemx 0x17 N_SETT | N_EXT -Text segment set element - -@item 0x18 N_SETD -@itemx 0x19 N_SETD | N_EXT -Data segment set element - -@item 0x1a N_SETB -@itemx 0x1b N_SETB | N_EXT -BSS segment set element - -@item 0x1c N_SETV -@itemx 0x1d N_SETV | N_EXT -Pointer to set vector - -@item 0x1e N_WARNING -Print a warning message during linking - -@item 0x1f N_FN -File name of a @file{.o} file -@end table - -@node Stab Symbol Types -@appendixsec Stab Symbol Types - -The following symbol types indicate that this is a stab. This is the -full list of stab numbers, including stab types that are used in -languages other than C. - -@table @code -@item 0x20 N_GSYM -Global symbol; see @ref{Global Variables}. - -@item 0x22 N_FNAME -Function name (for BSD Fortran); see @ref{Procedures}. - -@item 0x24 N_FUN -Function name (@pxref{Procedures}) or text segment variable -(@pxref{Statics}). - -@item 0x26 N_STSYM -Data segment file-scope variable; see @ref{Statics}. - -@item 0x28 N_LCSYM -BSS segment file-scope variable; see @ref{Statics}. - -@item 0x2a N_MAIN -Name of main routine; see @ref{Main Program}. - -@item 0x2c N_ROSYM -Variable in @code{.rodata} section; see @ref{Statics}. - -@item 0x30 N_PC -Global symbol (for Pascal); see @ref{N_PC}. - -@item 0x32 N_NSYMS -Number of symbols (according to Ultrix V4.0); see @ref{N_NSYMS}. - -@item 0x34 N_NOMAP -No DST map; see @ref{N_NOMAP}. - -@c FIXME: describe this solaris feature in the body of the text (see -@c comments in include/aout/stab.def). -@item 0x38 N_OBJ -Object file (Solaris2). - -@c See include/aout/stab.def for (a little) more info. -@item 0x3c N_OPT -Debugger options (Solaris2). - -@item 0x40 N_RSYM -Register variable; see @ref{Register Variables}. - -@item 0x42 N_M2C -Modula-2 compilation unit; see @ref{N_M2C}. - -@item 0x44 N_SLINE -Line number in text segment; see @ref{Line Numbers}. - -@item 0x46 N_DSLINE -Line number in data segment; see @ref{Line Numbers}. - -@item 0x48 N_BSLINE -Line number in bss segment; see @ref{Line Numbers}. - -@item 0x48 N_BROWS -Sun source code browser, path to @file{.cb} file; see @ref{N_BROWS}. - -@item 0x4a N_DEFD -GNU Modula2 definition module dependency; see @ref{N_DEFD}. - -@item 0x4c N_FLINE -Function start/body/end line numbers (Solaris2). - -@item 0x50 N_EHDECL -GNU C++ exception variable; see @ref{N_EHDECL}. - -@item 0x50 N_MOD2 -Modula2 info "for imc" (according to Ultrix V4.0); see @ref{N_MOD2}. - -@item 0x54 N_CATCH -GNU C++ @code{catch} clause; see @ref{N_CATCH}. - -@item 0x60 N_SSYM -Structure of union element; see @ref{N_SSYM}. - -@item 0x62 N_ENDM -Last stab for module (Solaris2). - -@item 0x64 N_SO -Path and name of source file; see @ref{Source Files}. - -@item 0x80 N_LSYM -Stack variable (@pxref{Stack Variables}) or type (@pxref{Typedefs}). - -@item 0x82 N_BINCL -Beginning of an include file (Sun only); see @ref{Include Files}. - -@item 0x84 N_SOL -Name of include file; see @ref{Include Files}. - -@item 0xa0 N_PSYM -Parameter variable; see @ref{Parameters}. - -@item 0xa2 N_EINCL -End of an include file; see @ref{Include Files}. - -@item 0xa4 N_ENTRY -Alternate entry point; see @ref{Alternate Entry Points}. - -@item 0xc0 N_LBRAC -Beginning of a lexical block; see @ref{Block Structure}. - -@item 0xc2 N_EXCL -Place holder for a deleted include file; see @ref{Include Files}. - -@item 0xc4 N_SCOPE -Modula2 scope information (Sun linker); see @ref{N_SCOPE}. - -@item 0xe0 N_RBRAC -End of a lexical block; see @ref{Block Structure}. - -@item 0xe2 N_BCOMM -Begin named common block; see @ref{Common Blocks}. - -@item 0xe4 N_ECOMM -End named common block; see @ref{Common Blocks}. - -@item 0xe8 N_ECOML -Member of a common block; see @ref{Common Blocks}. - -@c FIXME: How does this really work? Move it to main body of document. -@item 0xea N_WITH -Pascal @code{with} statement: type,,0,0,offset (Solaris2). - -@item 0xf0 N_NBTEXT -Gould non-base registers; see @ref{Gould}. - -@item 0xf2 N_NBDATA -Gould non-base registers; see @ref{Gould}. - -@item 0xf4 N_NBBSS -Gould non-base registers; see @ref{Gould}. - -@item 0xf6 N_NBSTS -Gould non-base registers; see @ref{Gould}. - -@item 0xf8 N_NBLCS -Gould non-base registers; see @ref{Gould}. -@end table - -@c Restore the default table indent -@iftex -@tableindent=.8in -@end iftex - -@node Symbol Descriptors -@appendix Table of Symbol Descriptors - -The symbol descriptor is the character which follows the colon in many -stabs, and which tells what kind of stab it is. @xref{String Field}, -for more information about their use. - -@c Please keep this alphabetical -@table @code -@c In TeX, this looks great, digit is in italics. But makeinfo insists -@c on putting it in `', not realizing that @var should override @code. -@c I don't know of any way to make makeinfo do the right thing. Seems -@c like a makeinfo bug to me. -@item @var{digit} -@itemx ( -@itemx - -Variable on the stack; see @ref{Stack Variables}. - -@item : -C++ nested symbol; see @xref{Nested Symbols} - -@item a -Parameter passed by reference in register; see @ref{Reference Parameters}. - -@item b -Based variable; see @ref{Based Variables}. - -@item c -Constant; see @ref{Constants}. - -@item C -Conformant array bound (Pascal, maybe other languages); @ref{Conformant -Arrays}. Name of a caught exception (GNU C++). These can be -distinguished because the latter uses @code{N_CATCH} and the former uses -another symbol type. - -@item d -Floating point register variable; see @ref{Register Variables}. - -@item D -Parameter in floating point register; see @ref{Register Parameters}. - -@item f -File scope function; see @ref{Procedures}. - -@item F -Global function; see @ref{Procedures}. - -@item G -Global variable; see @ref{Global Variables}. - -@item i -@xref{Register Parameters}. - -@item I -Internal (nested) procedure; see @ref{Nested Procedures}. - -@item J -Internal (nested) function; see @ref{Nested Procedures}. - -@item L -Label name (documented by AIX, no further information known). - -@item m -Module; see @ref{Procedures}. - -@item p -Argument list parameter; see @ref{Parameters}. - -@item pP -@xref{Parameters}. - -@item pF -Fortran Function parameter; see @ref{Parameters}. - -@item P -Unfortunately, three separate meanings have been independently invented -for this symbol descriptor. At least the GNU and Sun uses can be -distinguished by the symbol type. Global Procedure (AIX) (symbol type -used unknown); see @ref{Procedures}. Register parameter (GNU) (symbol -type @code{N_PSYM}); see @ref{Parameters}. Prototype of function -referenced by this file (Sun @code{acc}) (symbol type @code{N_FUN}). - -@item Q -Static Procedure; see @ref{Procedures}. - -@item R -Register parameter; see @ref{Register Parameters}. - -@item r -Register variable; see @ref{Register Variables}. - -@item S -File scope variable; see @ref{Statics}. - -@item s -Local variable (OS9000). - -@item t -Type name; see @ref{Typedefs}. - -@item T -Enumeration, structure, or union tag; see @ref{Typedefs}. - -@item v -Parameter passed by reference; see @ref{Reference Parameters}. - -@item V -Procedure scope static variable; see @ref{Statics}. - -@item x -Conformant array; see @ref{Conformant Arrays}. - -@item X -Function return variable; see @ref{Parameters}. -@end table - -@node Type Descriptors -@appendix Table of Type Descriptors - -The type descriptor is the character which follows the type number and -an equals sign. It specifies what kind of type is being defined. -@xref{String Field}, for more information about their use. - -@table @code -@item @var{digit} -@itemx ( -Type reference; see @ref{String Field}. - -@item - -Reference to builtin type; see @ref{Negative Type Numbers}. - -@item # -Method (C++); see @ref{Method Type Descriptor}. - -@item * -Pointer; see @ref{Miscellaneous Types}. - -@item & -Reference (C++). - -@item @@ -Type Attributes (AIX); see @ref{String Field}. Member (class and variable) -type (GNU C++); see @ref{Member Type Descriptor}. - -@item a -Array; see @ref{Arrays}. - -@item A -Open array; see @ref{Arrays}. - -@item b -Pascal space type (AIX); see @ref{Miscellaneous Types}. Builtin integer -type (Sun); see @ref{Builtin Type Descriptors}. Const and volatile -qualfied type (OS9000). - -@item B -Volatile-qualified type; see @ref{Miscellaneous Types}. - -@item c -Complex builtin type (AIX); see @ref{Builtin Type Descriptors}. -Const-qualified type (OS9000). - -@item C -COBOL Picture type. See AIX documentation for details. - -@item d -File type; see @ref{Miscellaneous Types}. - -@item D -N-dimensional dynamic array; see @ref{Arrays}. - -@item e -Enumeration type; see @ref{Enumerations}. - -@item E -N-dimensional subarray; see @ref{Arrays}. - -@item f -Function type; see @ref{Function Types}. - -@item F -Pascal function parameter; see @ref{Function Types} - -@item g -Builtin floating point type; see @ref{Builtin Type Descriptors}. - -@item G -COBOL Group. See AIX documentation for details. - -@item i -Imported type (AIX); see @ref{Cross-References}. Volatile-qualified -type (OS9000). - -@item k -Const-qualified type; see @ref{Miscellaneous Types}. - -@item K -COBOL File Descriptor. See AIX documentation for details. - -@item M -Multiple instance type; see @ref{Miscellaneous Types}. - -@item n -String type; see @ref{Strings}. - -@item N -Stringptr; see @ref{Strings}. - -@item o -Opaque type; see @ref{Typedefs}. - -@item p -Procedure; see @ref{Function Types}. - -@item P -Packed array; see @ref{Arrays}. - -@item r -Range type; see @ref{Subranges}. - -@item R -Builtin floating type; see @ref{Builtin Type Descriptors} (Sun). Pascal -subroutine parameter; see @ref{Function Types} (AIX). Detecting this -conflict is possible with careful parsing (hint: a Pascal subroutine -parameter type will always contain a comma, and a builtin type -descriptor never will). - -@item s -Structure type; see @ref{Structures}. - -@item S -Set type; see @ref{Miscellaneous Types}. - -@item u -Union; see @ref{Unions}. - -@item v -Variant record. This is a Pascal and Modula-2 feature which is like a -union within a struct in C. See AIX documentation for details. - -@item w -Wide character; see @ref{Builtin Type Descriptors}. - -@item x -Cross-reference; see @ref{Cross-References}. - -@item Y -Used by IBM's xlC C++ compiler (for structures, I think). - -@item z -gstring; see @ref{Strings}. -@end table - -@node Expanded Reference -@appendix Expanded Reference by Stab Type - -@c FIXME: This appendix should go away; see N_PSYM or N_SO for an example. - -For a full list of stab types, and cross-references to where they are -described, see @ref{Stab Types}. This appendix just duplicates certain -information from the main body of this document; eventually the -information will all be in one place. - -Format of an entry: - -The first line is the symbol type (see @file{include/aout/stab.def}). - -The second line describes the language constructs the symbol type -represents. - -The third line is the stab format with the significant stab fields -named and the rest NIL. - -Subsequent lines expand upon the meaning and possible values for each -significant stab field. - -Finally, any further information. - -@menu -* N_PC:: Pascal global symbol -* N_NSYMS:: Number of symbols -* N_NOMAP:: No DST map -* N_M2C:: Modula-2 compilation unit -* N_BROWS:: Path to .cb file for Sun source code browser -* N_DEFD:: GNU Modula2 definition module dependency -* N_EHDECL:: GNU C++ exception variable -* N_MOD2:: Modula2 information "for imc" -* N_CATCH:: GNU C++ "catch" clause -* N_SSYM:: Structure or union element -* N_SCOPE:: Modula2 scope information (Sun only) -* Gould:: non-base register symbols used on Gould systems -* N_LENG:: Length of preceding entry -@end menu - -@node N_PC -@section N_PC - -@deffn @code{.stabs} N_PC -@findex N_PC -Global symbol (for Pascal). - -@example -"name" -> "symbol_name" <<?>> -value -> supposedly the line number (stab.def is skeptical) -@end example - -@display -@file{stabdump.c} says: - -global pascal symbol: name,,0,subtype,line -<< subtype? >> -@end display -@end deffn - -@node N_NSYMS -@section N_NSYMS - -@deffn @code{.stabn} N_NSYMS -@findex N_NSYMS -Number of symbols (according to Ultrix V4.0). - -@display - 0, files,,funcs,lines (stab.def) -@end display -@end deffn - -@node N_NOMAP -@section N_NOMAP - -@deffn @code{.stabs} N_NOMAP -@findex N_NOMAP -No DST map for symbol (according to Ultrix V4.0). I think this means a -variable has been optimized out. - -@display - name, ,0,type,ignored (stab.def) -@end display -@end deffn - -@node N_M2C -@section N_M2C - -@deffn @code{.stabs} N_M2C -@findex N_M2C -Modula-2 compilation unit. - -@example -"string" -> "unit_name,unit_time_stamp[,code_time_stamp]" -desc -> unit_number -value -> 0 (main unit) - 1 (any other unit) -@end example - -See @cite{Dbx and Dbxtool Interfaces}, 2nd edition, by Sun, 1988, for -more information. - -@end deffn - -@node N_BROWS -@section N_BROWS - -@deffn @code{.stabs} N_BROWS -@findex N_BROWS -Sun source code browser, path to @file{.cb} file - -<<?>> -"path to associated @file{.cb} file" - -Note: N_BROWS has the same value as N_BSLINE. -@end deffn - -@node N_DEFD -@section N_DEFD - -@deffn @code{.stabn} N_DEFD -@findex N_DEFD -GNU Modula2 definition module dependency. - -GNU Modula-2 definition module dependency. The value is the -modification time of the definition file. The other field is non-zero -if it is imported with the GNU M2 keyword @code{%INITIALIZE}. Perhaps -@code{N_M2C} can be used if there are enough empty fields? -@end deffn - -@node N_EHDECL -@section N_EHDECL - -@deffn @code{.stabs} N_EHDECL -@findex N_EHDECL -GNU C++ exception variable <<?>>. - -"@var{string} is variable name" - -Note: conflicts with @code{N_MOD2}. -@end deffn - -@node N_MOD2 -@section N_MOD2 - -@deffn @code{.stab?} N_MOD2 -@findex N_MOD2 -Modula2 info "for imc" (according to Ultrix V4.0) - -Note: conflicts with @code{N_EHDECL} <<?>> -@end deffn - -@node N_CATCH -@section N_CATCH - -@deffn @code{.stabn} N_CATCH -@findex N_CATCH -GNU C++ @code{catch} clause - -GNU C++ @code{catch} clause. The value is its address. The desc field -is nonzero if this entry is immediately followed by a @code{CAUGHT} stab -saying what exception was caught. Multiple @code{CAUGHT} stabs means -that multiple exceptions can be caught here. If desc is 0, it means all -exceptions are caught here. -@end deffn - -@node N_SSYM -@section N_SSYM - -@deffn @code{.stabn} N_SSYM -@findex N_SSYM -Structure or union element. - -The value is the offset in the structure. - -<<?looking at structs and unions in C I didn't see these>> -@end deffn - -@node N_SCOPE -@section N_SCOPE - -@deffn @code{.stab?} N_SCOPE -@findex N_SCOPE -Modula2 scope information (Sun linker) -<<?>> -@end deffn - -@node Gould -@section Non-base registers on Gould systems - -@deffn @code{.stab?} N_NBTEXT -@deffnx @code{.stab?} N_NBDATA -@deffnx @code{.stab?} N_NBBSS -@deffnx @code{.stab?} N_NBSTS -@deffnx @code{.stab?} N_NBLCS -@findex N_NBTEXT -@findex N_NBDATA -@findex N_NBBSS -@findex N_NBSTS -@findex N_NBLCS -These are used on Gould systems for non-base registers syms. - -However, the following values are not the values used by Gould; they are -the values which GNU has been documenting for these values for a long -time, without actually checking what Gould uses. I include these values -only because perhaps some someone actually did something with the GNU -information (I hope not, why GNU knowingly assigned wrong values to -these in the header file is a complete mystery to me). - -@example -240 0xf0 N_NBTEXT ?? -242 0xf2 N_NBDATA ?? -244 0xf4 N_NBBSS ?? -246 0xf6 N_NBSTS ?? -248 0xf8 N_NBLCS ?? -@end example -@end deffn - -@node N_LENG -@section N_LENG - -@deffn @code{.stabn} N_LENG -@findex N_LENG -Second symbol entry containing a length-value for the preceding entry. -The value is the length. -@end deffn - -@node Questions -@appendix Questions and Anomalies - -@itemize @bullet -@item -@c I think this is changed in GCC 2.4.5 to put the line number there. -For GNU C stabs defining local and global variables (@code{N_LSYM} and -@code{N_GSYM}), the desc field is supposed to contain the source -line number on which the variable is defined. In reality the desc -field is always 0. (This behavior is defined in @file{dbxout.c} and -putting a line number in desc is controlled by @samp{#ifdef -WINNING_GDB}, which defaults to false). GDB supposedly uses this -information if you say @samp{list @var{var}}. In reality, @var{var} can -be a variable defined in the program and GDB says @samp{function -@var{var} not defined}. - -@item -In GNU C stabs, there seems to be no way to differentiate tag types: -structures, unions, and enums (symbol descriptor @samp{T}) and typedefs -(symbol descriptor @samp{t}) defined at file scope from types defined locally -to a procedure or other more local scope. They all use the @code{N_LSYM} -stab type. Types defined at procedure scope are emited after the -@code{N_RBRAC} of the preceding function and before the code of the -procedure in which they are defined. This is exactly the same as -types defined in the source file between the two procedure bodies. -GDB overcompensates by placing all types in block #1, the block for -symbols of file scope. This is true for default, @samp{-ansi} and -@samp{-traditional} compiler options. (Bugs gcc/1063, gdb/1066.) - -@item -What ends the procedure scope? Is it the proc block's @code{N_RBRAC} or the -next @code{N_FUN}? (I believe its the first.) - -@item -@c FIXME: This should go with the other stuff about global variables. -Global variable stabs don't have location information. This comes -from the external symbol for the same variable. The external symbol -has a leading underbar on the _name of the variable and the stab does -not. How do we know these two symbol table entries are talking about -the same symbol when their names are different? (Answer: the debugger -knows that external symbols have leading underbars). - -@c FIXME: This is absurdly vague; there all kinds of differences, some -@c of which are the same between gnu & sun, and some of which aren't. -@c In particular, I'm pretty sure GCC works with Sun dbx by default. -@c @item -@c Can GCC be configured to output stabs the way the Sun compiler -@c does, so that their native debugging tools work? <NO?> It doesn't by -@c default. GDB reads either format of stab. (GCC or SunC). How about -@c dbx? -@end itemize - -@node XCOFF Differences -@appendix Differences Between GNU Stabs in a.out and GNU Stabs in XCOFF - -@c FIXME: Merge *all* these into the main body of the document. -The AIX/RS6000 native object file format is XCOFF with stabs. This -appendix only covers those differences which are not covered in the main -body of this document. - -@itemize @bullet -@item -BSD a.out stab types correspond to AIX XCOFF storage classes. In general -the mapping is @code{N_@var{stabtype}} becomes @code{C_@var{stabtype}}. -Some stab types in a.out are not supported in XCOFF; most of these use -@code{C_DECL}. - -@c FIXME: I think they are trying to say something about whether the -@c assembler defaults the value to the location counter. -@item -If the XCOFF stab is an @code{N_FUN} (@code{C_FUN}) then follow the -string field with @samp{,.} instead of just @samp{,}. -@end itemize - -I think that's it for @file{.s} file differences. They could stand to be -better presented. This is just a list of what I have noticed so far. -There are a @emph{lot} of differences in the information in the symbol -tables of the executable and object files. - -Mapping of a.out stab types to XCOFF storage classes: - -@example -stab type storage class -------------------------------- -N_GSYM C_GSYM -N_FNAME unused -N_FUN C_FUN -N_STSYM C_STSYM -N_LCSYM C_STSYM -N_MAIN unknown -N_PC unknown -N_RSYM C_RSYM -unknown C_RPSYM -N_M2C unknown -N_SLINE unknown -N_DSLINE unknown -N_BSLINE unknown -N_BROWSE unchanged -N_CATCH unknown -N_SSYM unknown -N_SO unknown -N_LSYM C_LSYM -various C_DECL -N_BINCL unknown -N_SOL unknown -N_PSYM C_PSYM -N_EINCL unknown -N_ENTRY C_ENTRY -N_LBRAC unknown -N_EXCL unknown -N_SCOPE unknown -N_RBRAC unknown -N_BCOMM C_BCOMM -N_ECOMM C_ECOMM -N_ECOML C_ECOML - -N_LENG unknown -@end example - -@node Sun Differences -@appendix Differences Between GNU Stabs and Sun Native Stabs - -@c FIXME: Merge all this stuff into the main body of the document. - -@itemize @bullet -@item -GNU C stabs define @emph{all} types, file or procedure scope, as -@code{N_LSYM}. Sun doc talks about using @code{N_GSYM} too. - -@item -Sun C stabs use type number pairs in the format -(@var{file-number},@var{type-number}) where @var{file-number} is a -number starting with 1 and incremented for each sub-source file in the -compilation. @var{type-number} is a number starting with 1 and -incremented for each new type defined in the compilation. GNU C stabs -use the type number alone, with no source file number. -@end itemize - -@node Stab Sections -@appendix Using Stabs in Their Own Sections - -Many object file formats allow tools to create object files with custom -sections containing any arbitrary data. For any such object file -format, stabs can be embedded in special sections. This is how stabs -are used with ELF and SOM, and aside from ECOFF and XCOFF, is how stabs -are used with COFF. - -@menu -* Stab Section Basics:: How to embed stabs in sections -* ELF Linker Relocation:: Sun ELF hacks -@end menu - -@node Stab Section Basics -@appendixsec How to Embed Stabs in Sections - -The assembler creates two custom sections, a section named @code{.stab} -which contains an array of fixed length structures, one struct per stab, -and a section named @code{.stabstr} containing all the variable length -strings that are referenced by stabs in the @code{.stab} section. The -byte order of the stabs binary data depends on the object file format. -For ELF, it matches the byte order of the ELF file itself, as determined -from the @code{EI_DATA} field in the @code{e_ident} member of the ELF -header. For SOM, it is always big-endian (is this true??? FIXME). For -COFF, it matches the byte order of the COFF headers. The meaning of the -fields is the same as for a.out (@pxref{Symbol Table Format}), except -that the @code{n_strx} field is relative to the strings for the current -compilation unit (which can be found using the synthetic N_UNDF stab -described below), rather than the entire string table. - -The first stab in the @code{.stab} section for each compilation unit is -synthetic, generated entirely by the assembler, with no corresponding -@code{.stab} directive as input to the assembler. This stab contains -the following fields: - -@table @code -@item n_strx -Offset in the @code{.stabstr} section to the source filename. - -@item n_type -@code{N_UNDF}. - -@item n_other -Unused field, always zero. -This may eventually be used to hold overflows from the count in -the @code{n_desc} field. - -@item n_desc -Count of upcoming symbols, i.e., the number of remaining stabs for this -source file. - -@item n_value -Size of the string table fragment associated with this source file, in -bytes. -@end table - -The @code{.stabstr} section always starts with a null byte (so that string -offsets of zero reference a null string), followed by random length strings, -each of which is null byte terminated. - -The ELF section header for the @code{.stab} section has its -@code{sh_link} member set to the section number of the @code{.stabstr} -section, and the @code{.stabstr} section has its ELF section -header @code{sh_type} member set to @code{SHT_STRTAB} to mark it as a -string table. SOM and COFF have no way of linking the sections together -or marking them as string tables. - -For COFF, the @code{.stab} and @code{.stabstr} sections are simply -concatenated by the linker. GDB then uses the @code{n_desc} fields to -figure out the extent of the original sections. Similarly, the -@code{n_value} fields of the header symbols are added together in order -to get the actual position of the strings in a desired @code{.stabstr} -section. Although this design obviates any need for the linker to relocate -or otherwise manipulate @code{.stab} and @code{.stabstr} sections, it also -requires some care to ensure that the offsets are calculated correctly. -For instance, if the linker were to pad in between the @code{.stabstr} -sections before concatenating, then the offsets to strings in the middle -of the executable's @code{.stabstr} section would be wrong. - -@node ELF Linker Relocation -@appendixsec Having the Linker Relocate Stabs in ELF - -This section describes some Sun hacks for Stabs in ELF; it does not -apply to COFF or SOM. - -To keep linking fast, you don't want the linker to have to relocate very -many stabs. Making sure this is done for @code{N_SLINE}, -@code{N_RBRAC}, and @code{N_LBRAC} stabs is the most important thing -(see the descriptions of those stabs for more information). But Sun's -stabs in ELF has taken this further, to make all addresses in the -@code{n_value} field (functions and static variables) relative to the -source file. For the @code{N_SO} symbol itself, Sun simply omits the -address. To find the address of each section corresponding to a given -source file, the compiler puts out symbols giving the address of each -section for a given source file. Since these are ELF (not stab) -symbols, the linker relocates them correctly without having to touch the -stabs section. They are named @code{Bbss.bss} for the bss section, -@code{Ddata.data} for the data section, and @code{Drodata.rodata} for -the rodata section. For the text section, there is no such symbol (but -there should be, see below). For an example of how these symbols work, -@xref{Stab Section Transformations}. GCC does not provide these symbols; -it instead relies on the stabs getting relocated. Thus addresses which -would normally be relative to @code{Bbss.bss}, etc., are already -relocated. The Sun linker provided with Solaris 2.2 and earlier -relocates stabs using normal ELF relocation information, as it would do -for any section. Sun has been threatening to kludge their linker to not -do this (to speed up linking), even though the correct way to avoid -having the linker do these relocations is to have the compiler no longer -output relocatable values. Last I heard they had been talked out of the -linker kludge. See Sun point patch 101052-01 and Sun bug 1142109. With -the Sun compiler this affects @samp{S} symbol descriptor stabs -(@pxref{Statics}) and functions (@pxref{Procedures}). In the latter -case, to adopt the clean solution (making the value of the stab relative -to the start of the compilation unit), it would be necessary to invent a -@code{Ttext.text} symbol, analogous to the @code{Bbss.bss}, etc., -symbols. I recommend this rather than using a zero value and getting -the address from the ELF symbols. - -Finding the correct @code{Bbss.bss}, etc., symbol is difficult, because -the linker simply concatenates the @code{.stab} sections from each -@file{.o} file without including any information about which part of a -@code{.stab} section comes from which @file{.o} file. The way GDB does -this is to look for an ELF @code{STT_FILE} symbol which has the same -name as the last component of the file name from the @code{N_SO} symbol -in the stabs (for example, if the file name is @file{../../gdb/main.c}, -it looks for an ELF @code{STT_FILE} symbol named @code{main.c}). This -loses if different files have the same name (they could be in different -directories, a library could have been copied from one system to -another, etc.). It would be much cleaner to have the @code{Bbss.bss} -symbols in the stabs themselves. Having the linker relocate them there -is no more work than having the linker relocate ELF symbols, and it -solves the problem of having to associate the ELF and stab symbols. -However, no one has yet designed or implemented such a scheme. - -@node Symbol Types Index -@unnumbered Symbol Types Index - -@printindex fn - -@contents -@bye |