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Diffstat (limited to 'contrib/binutils/ld/ld.texinfo')
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1 files changed, 556 insertions, 200 deletions
diff --git a/contrib/binutils/ld/ld.texinfo b/contrib/binutils/ld/ld.texinfo index 8c4d98f..1069d03 100644 --- a/contrib/binutils/ld/ld.texinfo +++ b/contrib/binutils/ld/ld.texinfo @@ -9,6 +9,43 @@ @c @smallbook +@macro gcctabopt{body} +@code{\body\} +@end macro + +@c man begin NAME +@ifset man +@c Configure for the generation of man pages +@set UsesEnvVars +@set GENERIC +@set A29K +@set ARC +@set ARM +@set D10V +@set D30V +@set H8/300 +@set H8/500 +@set HPPA +@set I370 +@set I80386 +@set I860 +@set I960 +@set M32R +@set M68HC11 +@set M680X0 +@set MCORE +@set MIPS +@set MMIX +@set PDP11 +@set PJ +@set SH +@set SPARC +@set C54X +@set V850 +@set VAX +@end ifset +@c man end + @ifinfo @format START-INFO-DIR-ENTRY @@ -20,7 +57,8 @@ END-INFO-DIR-ENTRY @ifinfo This file documents the @sc{gnu} linker LD version @value{VERSION}. -Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc. +Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, +2001 Free Software Foundation, Inc. @ignore @@ -63,14 +101,16 @@ notice identical to this one except for the removal of this paragraph @end tex @vskip 0pt plus 1filll -Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc. +@c man begin COPYRIGHT +Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc. - Permission is granted to copy, distribute and/or modify this document - under the terms of the GNU Free Documentation License, Version 1.1 - or any later version published by the Free Software Foundation; - with no Invariant Sections, with no Front-Cover Texts, and with no - Back-Cover Texts. A copy of the license is included in the - section entitled "GNU Free Documentation License". +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.1 +or any later version published by the Free Software Foundation; +with no Invariant Sections, with no Front-Cover Texts, and with no +Back-Cover Texts. A copy of the license is included in the +section entitled "GNU Free Documentation License". +@c man end @end titlepage @end iftex @@ -123,17 +163,40 @@ section entitled "GNU Free Documentation License". @cindex @sc{gnu} linker @cindex what is this? -@code{ld} combines a number of object and archive files, relocates + +@ifset man +@c man begin SYNOPSIS +ld [@b{options}] @var{objfile} @dots{} +@c man end + +@c man begin SEEALSO +ar(1), nm(1), objcopy(1), objdump(1), readelf(1) and +the Info entries for @file{binutils} and +@file{ld}. +@c man end +@end ifset + +@c man begin DESCRIPTION + +@command{ld} combines a number of object and archive files, relocates their data and ties up symbol references. Usually the last step in -compiling a program is to run @code{ld}. +compiling a program is to run @command{ld}. -@code{ld} accepts Linker Command Language files written in +@command{ld} accepts Linker Command Language files written in a superset of AT&T's Link Editor Command Language syntax, to provide explicit and total control over the linking process. +@ifset man +@c For the man only +This man page does not describe the command language; see the +@command{ld} entry in @code{info}, or the manual +ld: the GNU linker, for full details on the command language and +on other aspects of the GNU linker. +@end ifset + @ifclear SingleFormat -This version of @code{ld} uses the general purpose BFD libraries -to operate on object files. This allows @code{ld} to read, combine, and +This version of @command{ld} uses the general purpose BFD libraries +to operate on object files. This allows @command{ld} to read, combine, and write object files in many different formats---for example, COFF or @code{a.out}. Different formats may be linked together to produce any available kind of object file. @xref{BFD}, for more information. @@ -142,16 +205,22 @@ available kind of object file. @xref{BFD}, for more information. Aside from its flexibility, the @sc{gnu} linker is more helpful than other linkers in providing diagnostic information. Many linkers abandon execution immediately upon encountering an error; whenever possible, -@code{ld} continues executing, allowing you to identify other errors +@command{ld} continues executing, allowing you to identify other errors (or, in some cases, to get an output file in spite of the error). +@c man end + @node Invocation @chapter Invocation -The @sc{gnu} linker @code{ld} is meant to cover a broad range of situations, +@c man begin DESCRIPTION + +The @sc{gnu} linker @command{ld} is meant to cover a broad range of situations, and to be as compatible as possible with other linkers. As a result, you have many choices to control its behavior. +@c man end + @ifset UsesEnvVars @menu * Options:: Command Line Options @@ -164,10 +233,13 @@ you have many choices to control its behavior. @cindex command line @cindex options + +@c man begin OPTIONS + The linker supports a plethora of command-line options, but in actual practice few of them are used in any particular context. @cindex standard Unix system -For instance, a frequent use of @code{ld} is to link standard Unix +For instance, a frequent use of @command{ld} is to link standard Unix object files on a standard, supported Unix system. On such a system, to link a file @code{hello.o}: @@ -175,12 +247,12 @@ link a file @code{hello.o}: ld -o @var{output} /lib/crt0.o hello.o -lc @end smallexample -This tells @code{ld} to produce a file called @var{output} as the +This tells @command{ld} to produce a file called @var{output} as the result of linking the file @code{/lib/crt0.o} with @code{hello.o} and the library @code{libc.a}, which will come from the standard search directories. (See the discussion of the @samp{-l} option below.) -Some of the command-line options to @code{ld} may be specified at any +Some of the command-line options to @command{ld} may be specified at any point in the command line. However, options which refer to files, such as @samp{-l} or @samp{-T}, cause the file to be read at the point at which the option appears in the command line, relative to the object @@ -209,10 +281,8 @@ linker script or the one specified by using @samp{-T}). This feature permits the linker to link against a file which appears to be an object or an archive, but actually merely defines some symbol values, or uses @code{INPUT} or @code{GROUP} to load other objects. Note that -specifying a script in this way should only be used to augment the main -linker script; if you want to use some command that logically can only -appear once, such as the @code{SECTIONS} or @code{MEMORY} command, you -must replace the default linker script using the @samp{-T} option. +specifying a script in this way merely augments the main linker script; +use the @samp{-T} option to replace the default linker script entirely. @xref{Scripts}. For options whose names are a single letter, @@ -251,7 +321,7 @@ silently drop the linker options, resulting in a bad link. Here is a table of the generic command line switches accepted by the GNU linker: -@table @code +@table @gcctabopt @kindex -a@var{keyword} @item -a@var{keyword} This option is supported for HP/UX compatibility. The @var{keyword} @@ -266,14 +336,14 @@ to @samp{-Bdynamic}. This option may be used any number of times. @item -A@var{architecture} @kindex --architecture=@var{arch} @itemx --architecture=@var{architecture} -In the current release of @code{ld}, this option is useful only for the -Intel 960 family of architectures. In that @code{ld} configuration, the +In the current release of @command{ld}, this option is useful only for the +Intel 960 family of architectures. In that @command{ld} configuration, the @var{architecture} argument identifies the particular architecture in the 960 family, enabling some safeguards and modifying the -archive-library search path. @xref{i960,,@code{ld} and the Intel 960 +archive-library search path. @xref{i960,,@command{ld} and the Intel 960 family}, for details. -Future releases of @code{ld} may support similar functionality for +Future releases of @command{ld} may support similar functionality for other architecture families. @end ifset @@ -285,12 +355,12 @@ other architecture families. @cindex input format @item -b @var{input-format} @itemx --format=@var{input-format} -@code{ld} may be configured to support more than one kind of object -file. If your @code{ld} is configured this way, you can use the +@command{ld} may be configured to support more than one kind of object +file. If your @command{ld} is configured this way, you can use the @samp{-b} option to specify the binary format for input object files -that follow this option on the command line. Even when @code{ld} is +that follow this option on the command line. Even when @command{ld} is configured to support alternative object formats, you don't usually need -to specify this, as @code{ld} should be configured to expect as a +to specify this, as @command{ld} should be configured to expect as a default input format the most usual format on each machine. @var{input-format} is a text string, the name of a particular format supported by the BFD libraries. (You can list the available binary @@ -309,7 +379,10 @@ The default format is taken from the environment variable @xref{Environment}. @end ifset You can also define the input format from a script, using the command -@code{TARGET}; see @ref{Format Commands}. +@code{TARGET}; +@ifclear man +see @ref{Format Commands}. +@end ifclear @end ifclear @kindex -c @var{MRI-cmdfile} @@ -317,12 +390,18 @@ You can also define the input format from a script, using the command @cindex compatibility, MRI @item -c @var{MRI-commandfile} @itemx --mri-script=@var{MRI-commandfile} -For compatibility with linkers produced by MRI, @code{ld} accepts script +For compatibility with linkers produced by MRI, @command{ld} accepts script files written in an alternate, restricted command language, described in -@ref{MRI,,MRI Compatible Script Files}. Introduce MRI script files with +@ifclear man +@ref{MRI,,MRI Compatible Script Files}. +@end ifclear +@ifset man +the MRI Compatible Script Files section of GNU ld documentation. +@end ifset +Introduce MRI script files with the option @samp{-c}; use the @samp{-T} option to run linker -scripts written in the general-purpose @code{ld} scripting language. -If @var{MRI-cmdfile} does not exist, @code{ld} looks for it in the directories +scripts written in the general-purpose @command{ld} scripting language. +If @var{MRI-cmdfile} does not exist, @command{ld} looks for it in the directories specified by any @samp{-L} options. @cindex common allocation @@ -369,6 +448,10 @@ back to the symbols defined by the program, rather than some other dynamic object, then you will probably need to use this option when linking the program itself. +You can also use the version script to control what symbols should +be added to the dynamic symbol table if the output format supports it. +See the description of @samp{--version-script} in @ref{VERSION}. + @cindex big-endian objects @cindex endianness @kindex -EB @@ -419,12 +502,12 @@ found in the shared object @var{name}. Thus the filter object can be used to select a subset of the symbols provided by the object @var{name}. -Some older linkers used the @code{-F} option throughout a compilation +Some older linkers used the @option{-F} option throughout a compilation toolchain for specifying object-file format for both input and output object files. The @sc{gnu} linker uses other mechanisms for this -purpose: the @code{-b}, @code{--format}, @code{--oformat} options, the +purpose: the @option{-b}, @option{--format}, @option{--oformat} options, the @code{TARGET} command in linker scripts, and the @code{GNUTARGET} -environment variable. The @sc{gnu} linker will ignore the @code{-F} +environment variable. The @sc{gnu} linker will ignore the @option{-F} option when not creating an ELF shared object. @cindex finalization function @@ -479,13 +562,13 @@ function to call. @item -l@var{archive} @itemx --library=@var{archive} Add archive file @var{archive} to the list of files to link. This -option may be used any number of times. @code{ld} will search its +option may be used any number of times. @command{ld} will search its path-list for occurrences of @code{lib@var{archive}.a} for every @var{archive} specified. -On systems which support shared libraries, @code{ld} may also search for +On systems which support shared libraries, @command{ld} may also search for libraries with extensions other than @code{.a}. Specifically, on ELF -and SunOS systems, @code{ld} will search a directory for a library with +and SunOS systems, @command{ld} will search a directory for a library with an extension of @code{.so} before searching for one with an extension of @code{.a}. By convention, a @code{.so} extension indicates a shared library. @@ -497,14 +580,14 @@ command line, the linker will include the appropriate file(s) from the archive. However, an undefined symbol in an object appearing later on the command line will not cause the linker to search the archive again. -See the @code{-(} option for a way to force the linker to search +See the @option{-(} option for a way to force the linker to search archives multiple times. You may list the same archive multiple times on the command line. @ifset GENERIC This type of archive searching is standard for Unix linkers. However, -if you are using @code{ld} on AIX, note that it is different from the +if you are using @command{ld} on AIX, note that it is different from the behaviour of the AIX linker. @end ifset @@ -513,17 +596,17 @@ behaviour of the AIX linker. @kindex --library-path=@var{dir} @item -L@var{searchdir} @itemx --library-path=@var{searchdir} -Add path @var{searchdir} to the list of paths that @code{ld} will search -for archive libraries and @code{ld} control scripts. You may use this +Add path @var{searchdir} to the list of paths that @command{ld} will search +for archive libraries and @command{ld} control scripts. You may use this option any number of times. The directories are searched in the order in which they are specified on the command line. Directories specified on the command line are searched before the default directories. All -@code{-L} options apply to all @code{-l} options, regardless of the +@option{-L} options apply to all @option{-l} options, regardless of the order in which the options appear. @ifset UsesEnvVars The default set of paths searched (without being specified with -@samp{-L}) depends on which emulation mode @code{ld} is using, and in +@samp{-L}) depends on which emulation mode @command{ld} is using, and in some cases also on how it was configured. @xref{Environment}. @end ifset @@ -585,14 +668,14 @@ style magic numbers, mark the output as @code{OMAGIC}. @cindex naming the output file @item -o @var{output} @itemx --output=@var{output} -Use @var{output} as the name for the program produced by @code{ld}; if this +Use @var{output} as the name for the program produced by @command{ld}; if this option is not specified, the name @file{a.out} is used by default. The script command @code{OUTPUT} can also specify the output file name. @kindex -O @var{level} @cindex generating optimized output @item -O @var{level} -If @var{level} is a numeric values greater than zero @code{ld} optimizes +If @var{level} is a numeric values greater than zero @command{ld} optimizes the output. This might take significantly longer and therefore probably should only be enabled for the final binary. @@ -606,6 +689,8 @@ Post link analysis and optimization tools may need this information in order to perform correct modifications of executables. This results in larger executables. +This option is currently only supported on ELF platforms. + @cindex partial link @cindex relocatable output @kindex -r @@ -613,15 +698,21 @@ in larger executables. @item -r @itemx --relocateable Generate relocatable output---i.e., generate an output file that can in -turn serve as input to @code{ld}. This is often called @dfn{partial +turn serve as input to @command{ld}. This is often called @dfn{partial linking}. As a side effect, in environments that support standard Unix magic numbers, this option also sets the output file's magic number to @code{OMAGIC}. -@c ; see @code{-N}. +@c ; see @option{-N}. If this option is not specified, an absolute file is produced. When linking C++ programs, this option @emph{will not} resolve references to constructors; to do that, use @samp{-Ur}. +When an input file does not have the same format as the output file, +partial linking is only supported if that input file does not contain any +relocations. Different output formats can have further restrictions; for +example some @code{a.out}-based formats do not support partial linking +with input files in other formats at all. + This option does the same thing as @samp{-i}. @kindex -R @var{file} @@ -634,9 +725,9 @@ relocate it or include it in the output. This allows your output file to refer symbolically to absolute locations of memory defined in other programs. You may use this option more than once. -For compatibility with other ELF linkers, if the @code{-R} option is +For compatibility with other ELF linkers, if the @option{-R} option is followed by a directory name, rather than a file name, it is treated as -the @code{-rpath} option. +the @option{-rpath} option. @kindex -s @kindex --strip-all @@ -657,7 +748,7 @@ Omit debugger symbol information (but not all symbols) from the output file. @cindex input files, displaying @item -t @itemx --trace -Print the names of the input files as @code{ld} processes them. +Print the names of the input files as @command{ld} processes them. @kindex -T @var{script} @kindex --script=@var{script} @@ -665,14 +756,12 @@ Print the names of the input files as @code{ld} processes them. @item -T @var{scriptfile} @itemx --script=@var{scriptfile} Use @var{scriptfile} as the linker script. This script replaces -@code{ld}'s default linker script (rather than adding to it), so +@command{ld}'s default linker script (rather than adding to it), so @var{commandfile} must specify everything necessary to describe the -output file. You must use this option if you want to use a command -which can only appear once in a linker script, such as the -@code{SECTIONS} or @code{MEMORY} command. @xref{Scripts}. If -@var{scriptfile} does not exist in the current directory, @code{ld} -looks for it in the directories specified by any preceding @samp{-L} -options. Multiple @samp{-T} options accumulate. +output file. @xref{Scripts}. If @var{scriptfile} does not exist in +the current directory, @code{ld} looks for it in the directories +specified by any preceding @samp{-L} options. Multiple @samp{-T} +options accumulate. @kindex -u @var{symbol} @kindex --undefined=@var{symbol} @@ -690,7 +779,7 @@ option is equivalent to the @code{EXTERN} linker script command. @item -Ur For anything other than C++ programs, this option is equivalent to @samp{-r}: it generates relocatable output---i.e., an output file that can in -turn serve as input to @code{ld}. When linking C++ programs, @samp{-Ur} +turn serve as input to @command{ld}. When linking C++ programs, @samp{-Ur} @emph{does} resolve references to constructors, unlike @samp{-r}. It does not work to use @samp{-Ur} on files that were themselves linked with @samp{-Ur}; once the constructor table has been built, it cannot @@ -714,7 +803,7 @@ in a linker script. @item -v @itemx --version @itemx -V -Display the version number for @code{ld}. The @code{-V} option also +Display the version number for @command{ld}. The @option{-V} option also lists the supported emulations. @kindex -x @@ -754,7 +843,9 @@ for Solaris compatibility. @item -z @var{keyword} The recognized keywords are @code{initfirst}, @code{interpose}, @code{loadfltr}, @code{nodefaultlib}, @code{nodelete}, @code{nodlopen}, -@code{nodump}, @code{now} and @code{origin}. The other keywords are +@code{nodump}, @code{now}, @code{origin}, @code{combreloc}, @code{nocombreloc} +and @code{nocopyreloc}. +The other keywords are ignored for Solaris compatibility. @code{initfirst} marks the object to be initialized first at runtime before any other objects. @code{interpose} marks the object that its symbol table interposes @@ -768,6 +859,10 @@ of this object will ignore any default library search paths. @code{now} marks the object with the non-lazy runtime binding. @code{origin} marks the object may contain $ORIGIN. @code{defs} disallows undefined symbols. +@code{combreloc} combines multiple reloc sections and sorts them +to make dynamic symbol lookup caching possible. +@code{nocombreloc} disables multiple reloc sections combining. +@code{nocopyreloc} disables production of copy relocs. @kindex -( @cindex groups of archives @@ -804,14 +899,14 @@ for which shared libraries are supported. This option is normally the default on such platforms. The different variants of this option are for compatibility with various systems. You may use this option multiple times on the command line: it affects library searching for -@code{-l} options which follow it. +@option{-l} options which follow it. @kindex -Bgroup @item -Bgroup Set the @code{DF_1_GROUP} flag in the @code{DT_FLAGS_1} entry in the dynamic section. This causes the runtime linker to handle lookups in this object and its dependencies to be performed only inside the group. -@code{--no-undefined} is implied. This option is only meaningful on ELF +@option{--no-undefined} is implied. This option is only meaningful on ELF platforms which support shared libraries. @kindex -Bstatic @@ -826,7 +921,7 @@ Do not link against shared libraries. This is only meaningful on platforms for which shared libraries are supported. The different variants of this option are for compatibility with various systems. You may use this option multiple times on the command line: it affects -library searching for @code{-l} options which follow it. +library searching for @option{-l} options which follow it. @kindex -Bsymbolic @item -Bsymbolic @@ -860,6 +955,24 @@ sorted by name. For each symbol, a list of file names is given. If the symbol is defined, the first file listed is the location of the definition. The remaining files contain references to the symbol. +@cindex common allocation +@kindex --no-define-common +@item --no-define-common +This option inhibits the assignment of addresses to common symbols. +The script command @code{INHIBIT_COMMON_ALLOCATION} has the same effect. +@xref{Miscellaneous Commands}. + +The @samp{--no-define-common} option allows decoupling +the decision to assign addresses to Common symbols from the choice +of the output file type; otherwise a non-Relocatable output type +forces assigning addresses to Common symbols. +Using @samp{--no-define-common} allows Common symbols that are referenced +from a shared library to be assigned addresses only in the main program. +This eliminates the unused duplicate space in the shared library, +and also prevents any possible confusion over resolving to the wrong +duplicate when there are many dynamic modules with specialized search +paths for runtime symbol resolution. + @cindex symbols, from command line @kindex --defsym @var{symbol}=@var{exp} @item --defsym @var{symbol}=@var{expression} @@ -891,6 +1004,7 @@ demangle by default unless the environment variable @samp{COLLECT_NO_DEMANGLE} is set. These options may be used to override the default. @cindex dynamic linker, from command line +@kindex -I@var{file} @kindex --dynamic-linker @var{file} @item --dynamic-linker @var{file} Set the name of the dynamic linker. This is only meaningful when @@ -907,6 +1021,11 @@ assembler. It causes the linker to create a table which may be used at runtime to relocate any data which was statically initialized to pointer values. See the code in testsuite/ld-empic for details. + +@kindex --fatal-warnings +@item --fatal-warnings +Treat all warnings as errors. + @kindex --force-exe-suffix @item --force-exe-suffix Make sure that an output file has a .exe suffix. @@ -947,10 +1066,10 @@ Print a link map to the file @var{mapfile}. See the description of the @cindex memory usage @kindex --no-keep-memory @item --no-keep-memory -@code{ld} normally optimizes for speed over memory usage by caching the -symbol tables of input files in memory. This option tells @code{ld} to +@command{ld} normally optimizes for speed over memory usage by caching the +symbol tables of input files in memory. This option tells @command{ld} to instead optimize for memory usage, by rereading the symbol tables as -necessary. This may be required if @code{ld} runs out of memory space +necessary. This may be required if @command{ld} runs out of memory space while linking a large executable. @kindex --no-undefined @@ -959,7 +1078,7 @@ while linking a large executable. @itemx -z defs Normally when creating a non-symbolic shared library, undefined symbols are allowed and left to be resolved by the runtime loader. These options -disallow such undefined symbols. +disallows such undefined symbols. @kindex --allow-shlib-undefined @item --allow-shlib-undefined @@ -976,17 +1095,17 @@ is also normal for HPPA shared libraries to have undefined symbols. @kindex --no-warn-mismatch @item --no-warn-mismatch -Normally @code{ld} will give an error if you try to link together input +Normally @command{ld} will give an error if you try to link together input files that are mismatched for some reason, perhaps because they have been compiled for different processors or for different endiannesses. -This option tells @code{ld} that it should silently permit such possible +This option tells @command{ld} that it should silently permit such possible errors. This option should only be used with care, in cases when you have taken some special action that ensures that the linker errors are inappropriate. @kindex --no-whole-archive @item --no-whole-archive -Turn off the effect of the @code{--whole-archive} option for subsequent +Turn off the effect of the @option{--whole-archive} option for subsequent archive files. @cindex output file after errors @@ -1000,11 +1119,11 @@ when it issues any error whatsoever. @ifclear SingleFormat @kindex --oformat @item --oformat @var{output-format} -@code{ld} may be configured to support more than one kind of object -file. If your @code{ld} is configured this way, you can use the +@command{ld} may be configured to support more than one kind of object +file. If your @command{ld} is configured this way, you can use the @samp{--oformat} option to specify the binary format for the output -object file. Even when @code{ld} is configured to support alternative -object formats, you don't usually need to specify this, as @code{ld} +object file. Even when @command{ld} is configured to support alternative +object formats, you don't usually need to specify this, as @command{ld} should be configured to produce as a default output format the most usual format on each machine. @var{output-format} is a text string, the name of a particular format supported by the BFD libraries. (You can @@ -1030,10 +1149,10 @@ An option with machine dependent effects. This option is only supported on a few targets. @end ifset @ifset H8300 -@xref{H8/300,,@code{ld} and the H8/300}. +@xref{H8/300,,@command{ld} and the H8/300}. @end ifset @ifset I960 -@xref{i960,, @code{ld} and the Intel 960 family}. +@xref{i960,, @command{ld} and the Intel 960 family}. @end ifset @@ -1078,26 +1197,26 @@ line. It overrides @samp{-s} and @samp{-S}. @cindex runtime library search path @kindex -rpath Add a directory to the runtime library search path. This is used when -linking an ELF executable with shared objects. All @code{-rpath} +linking an ELF executable with shared objects. All @option{-rpath} arguments are concatenated and passed to the runtime linker, which uses -them to locate shared objects at runtime. The @code{-rpath} option is +them to locate shared objects at runtime. The @option{-rpath} option is also used when locating shared objects which are needed by shared objects explicitly included in the link; see the description of the -@code{-rpath-link} option. If @code{-rpath} is not used when linking an +@option{-rpath-link} option. If @option{-rpath} is not used when linking an ELF executable, the contents of the environment variable @code{LD_RUN_PATH} will be used if it is defined. -The @code{-rpath} option may also be used on SunOS. By default, on +The @option{-rpath} option may also be used on SunOS. By default, on SunOS, the linker will form a runtime search patch out of all the -@code{-L} options it is given. If a @code{-rpath} option is used, the -runtime search path will be formed exclusively using the @code{-rpath} -options, ignoring the @code{-L} options. This can be useful when using -gcc, which adds many @code{-L} options which may be on NFS mounted +@option{-L} options it is given. If a @option{-rpath} option is used, the +runtime search path will be formed exclusively using the @option{-rpath} +options, ignoring the @option{-L} options. This can be useful when using +gcc, which adds many @option{-L} options which may be on NFS mounted filesystems. -For compatibility with other ELF linkers, if the @code{-R} option is +For compatibility with other ELF linkers, if the @option{-R} option is followed by a directory name, rather than a file name, it is treated as -the @code{-rpath} option. +the @option{-rpath} option. @end ifset @ifset GENERIC @@ -1111,9 +1230,9 @@ of the input files. When the linker encounters such a dependency when doing a non-shared, non-relocatable link, it will automatically try to locate the required shared library and include it in the link, if it is not included -explicitly. In such a case, the @code{-rpath-link} option +explicitly. In such a case, the @option{-rpath-link} option specifies the first set of directories to search. The -@code{-rpath-link} option may specify a sequence of directory names +@option{-rpath-link} option may specify a sequence of directory names either by specifying a list of names separated by colons, or by appearing multiple times. @@ -1126,20 +1245,20 @@ The linker uses the following search paths to locate required shared libraries. @enumerate @item -Any directories specified by @code{-rpath-link} options. +Any directories specified by @option{-rpath-link} options. @item -Any directories specified by @code{-rpath} options. The difference -between @code{-rpath} and @code{-rpath-link} is that directories -specified by @code{-rpath} options are included in the executable and -used at runtime, whereas the @code{-rpath-link} option is only effective +Any directories specified by @option{-rpath} options. The difference +between @option{-rpath} and @option{-rpath-link} is that directories +specified by @option{-rpath} options are included in the executable and +used at runtime, whereas the @option{-rpath-link} option is only effective at link time. It is for the native linker only. @item -On an ELF system, if the @code{-rpath} and @code{rpath-link} options +On an ELF system, if the @option{-rpath} and @code{rpath-link} options were not used, search the contents of the environment variable @code{LD_RUN_PATH}. It is for the native linker only. @item -On SunOS, if the @code{-rpath} option was not used, search any -directories specified using @code{-L} options. +On SunOS, if the @option{-rpath} option was not used, search any +directories specified using @option{-L} options. @item For a native linker, the contents of the environment variable @code{LD_LIBRARY_PATH}. @@ -1166,20 +1285,20 @@ warning and continue with the link. @cindex shared libraries Create a shared library. This is currently only supported on ELF, XCOFF and SunOS platforms. On SunOS, the linker will automatically create a -shared library if the @code{-e} option is not used and there are +shared library if the @option{-e} option is not used and there are undefined symbols in the link. @item --sort-common @kindex --sort-common -This option tells @code{ld} to sort the common symbols by size when it +This option tells @command{ld} to sort the common symbols by size when it places them in the appropriate output sections. First come all the one -byte symbols, then all the two bytes, then all the four bytes, and then +byte symbols, then all the two byte, then all the four byte, and then everything else. This is to prevent gaps between symbols due to alignment constraints. @kindex --split-by-file @item --split-by-file [@var{size}] -Similar to @code{--split-by-reloc} but creates a new output section for +Similar to @option{--split-by-reloc} but creates a new output section for each input file when @var{size} is reached. @var{size} defaults to a size of 1 if not given. @@ -1204,16 +1323,16 @@ as execution time and memory usage. @kindex --traditional-format @cindex traditional format @item --traditional-format -For some targets, the output of @code{ld} is different in some ways from -the output of some existing linker. This switch requests @code{ld} to +For some targets, the output of @command{ld} is different in some ways from +the output of some existing linker. This switch requests @command{ld} to use the traditional format instead. @cindex dbx -For example, on SunOS, @code{ld} combines duplicate entries in the +For example, on SunOS, @command{ld} combines duplicate entries in the symbol string table. This can reduce the size of an output file with full debugging information by over 30 percent. Unfortunately, the SunOS @code{dbx} program can not read the resulting program (@code{gdb} has no -trouble). The @samp{--traditional-format} switch tells @code{ld} to not +trouble). The @samp{--traditional-format} switch tells @command{ld} to not combine duplicate entries. @kindex --section-start @var{sectionname}=@var{org} @@ -1245,9 +1364,9 @@ for compatibility with other linkers, you may omit the leading @cindex verbose @item --dll-verbose @itemx --verbose -Display the version number for @code{ld} and list the linker emulations +Display the version number for @command{ld} and list the linker emulations supported. Display which input files can and cannot be opened. Display -the linker script if using a default builtin script. +the linker script being used by the linker. @kindex --version-script=@var{version-scriptfile} @cindex version script, symbol versions @@ -1258,7 +1377,7 @@ about the version heirarchy for the library being created. This option is only meaningful on ELF platforms which support shared libraries. @xref{VERSION}. -@kindex --warn-comon +@kindex --warn-common @cindex warnings, on combining symbols @cindex combining symbols, warnings on @item --warn-common @@ -1384,15 +1503,15 @@ the section (@pxref{SECTIONS}). @cindex including an entire archive @item --whole-archive For each archive mentioned on the command line after the -@code{--whole-archive} option, include every object file in the archive +@option{--whole-archive} option, include every object file in the archive in the link, rather than searching the archive for the required object files. This is normally used to turn an archive file into a shared library, forcing every object to be included in the resulting shared library. This option may be used more than once. Two notes when using this option from gcc: First, gcc doesn't know -about this option, so you have to use @code{-Wl,-whole-archive}. -Second, don't forget to use @code{-Wl,-no-whole-archive} after your +about this option, so you have to use @option{-Wl,-whole-archive}. +Second, don't forget to use @option{-Wl,-no-whole-archive} after your list of archives, because gcc will add its own list of archives to your link and you may not want this flag to affect those as well. @@ -1419,13 +1538,13 @@ __wrap_malloc (int c) @} @end smallexample -If you link other code with this file using @code{--wrap malloc}, then +If you link other code with this file using @option{--wrap malloc}, then all calls to @code{malloc} will call the function @code{__wrap_malloc} instead. The call to @code{__real_malloc} in @code{__wrap_malloc} will call the real @code{malloc} function. You may wish to provide a @code{__real_malloc} function as well, so that -links without the @code{--wrap} option will succeed. If you do this, +links without the @option{--wrap} option will succeed. If you do this, you should not put the definition of @code{__real_malloc} in the same file as @code{__wrap_malloc}; if you do, the assembler may resolve the call before the linker has a chance to wrap it to @code{malloc}. @@ -1436,16 +1555,20 @@ call before the linker has a chance to wrap it to @code{malloc}. @itemx --disable-new-dtags This linker can create the new dynamic tags in ELF. But the older ELF systems may not understand them. If you specify -@code{--enable-new-dtags}, the dynamic tags will be created as needed. -If you specify @code{--disable-new-dtags}, no new dynamic tags will be +@option{--enable-new-dtags}, the dynamic tags will be created as needed. +If you specify @option{--disable-new-dtags}, no new dynamic tags will be created. By default, the new dynamic tags are not created. Note that those options are only available for ELF systems. @end table +@c man end + @subsection Options specific to i386 PE targets -The i386 PE linker supports the @code{-shared} option, which causes +@c man begin OPTIONS + +The i386 PE linker supports the @option{-shared} option, which causes the output to be a dynamically linked library (DLL) instead of a normal executable. You should name the output @code{*.dll} when you use this option. In addition, the linker fully supports the standard @@ -1459,7 +1582,7 @@ support additional command line options that are specific to the i386 PE target. Options that take values may be separated from their values by either a space or an equals sign. -@table @code +@table @gcctabopt @kindex --add-stdcall-alias @item --add-stdcall-alias @@ -1475,7 +1598,7 @@ addresses of all the relocations needed for generating DLLs with @kindex --dll @item --dll Create a DLL instead of a regular executable. You may also use -@code{-shared} or specify a @code{LIBRARY} in a given @code{.def} +@option{-shared} or specify a @code{LIBRARY} in a given @code{.def} file. @kindex --enable-stdcall-fixup @@ -1491,9 +1614,9 @@ undefined symbol @code{_foo} might be linked to the function to the function @code{_bar}. When the linker does this, it prints a warning, since it normally should have failed to link, but sometimes import libraries generated from third-party dlls may need this feature -to be usable. If you specify @code{--enable-stdcall-fixup}, this +to be usable. If you specify @option{--enable-stdcall-fixup}, this feature is fully enabled and warnings are not printed. If you specify -@code{--disable-stdcall-fixup}, this feature is disabled and such +@option{--disable-stdcall-fixup}, this feature is disabled and such mismatches are considered to be errors. @cindex DLLs, creating @@ -1505,8 +1628,22 @@ otherwise wouldn't be any exported symbols. When symbols are explicitly exported via DEF files or implicitly exported via function attributes, the default is to not export anything else unless this option is given. Note that the symbols @code{DllMain@@12}, -@code{DllEntryPoint@@0}, and @code{impure_ptr} will not be automatically -exported. +@code{DllEntryPoint@@0}, @code{DllMainCRTStartup@@12}, and +@code{impure_ptr} will not be automatically +exported. Also, symbols imported from other DLLs will not be +re-exported, nor will symbols specifying the DLL's internal layout +such as those beginning with @code{_head_} or ending with +@code{_iname}. In addition, no symbols from @code{libgcc}, +@code{libstd++}, @code{libmingw32}, or @code{crtX.o} will be exported. +Symbols whose names begin with @code{__rtti_} or @code{__builtin_} will +not be exported, to help with C++ DLLs. Finally, there is an +extensive list of cygwin-private symbols that are not exported +(obviously, this applies on when building DLLs for cygwin targets). +These cygwin-excludes are: @code{_cygwin_dll_entry@@12}, +@code{_cygwin_crt0_common@@8}, @code{_cygwin_noncygwin_dll_entry@@12}, +@code{_fmode}, @code{_impure_ptr}, @code{cygwin_attach_dll}, +@code{cygwin_premain0}, @code{cygwin_premain1}, @code{cygwin_premain2}, +@code{cygwin_premain3}, and @code{environ}. @kindex --exclude-symbols @item --exclude-symbols @var{symbol},@var{symbol},... @@ -1576,6 +1713,164 @@ file corresponding to the DLL the linker is generating. This DEF file library with @code{dlltool} or may be used as a reference to automatically or implicitly exported symbols. +@cindex DLLs, creating +@kindex --out-implib +@item --out-implib @var{file} +The linker will create the file @var{file} which will contain an +import lib corresponding to the DLL the linker is generating. This +import lib (which should be called @code{*.dll.a} or @code{*.a} +may be used to link clients against the generated DLL; this behavior +makes it possible to skip a separate @code{dlltool} import library +creation step. + +@kindex --enable-auto-image-base +@item --enable-auto-image-base +Automatically choose the image base for DLLs, unless one is specified +using the @code{--image-base} argument. By using a hash generated +from the dllname to create unique image bases for each DLL, in-memory +collisions and relocations which can delay program execution are +avoided. + +@kindex --disable-auto-image-base +@item --disable-auto-image-base +Do not automatically generate a unique image base. If there is no +user-specified image base (@code{--image-base}) then use the platform +default. + +@cindex DLLs, linking to +@kindex --dll-search-prefix +@item --dll-search-prefix @var{string} +When linking dynamically to a dll without an import library, i +search for @code{<string><basename>.dll} in preference to +@code{lib<basename>.dll}. This behavior allows easy distinction +between DLLs built for the various "subplatforms": native, cygwin, +uwin, pw, etc. For instance, cygwin DLLs typically use +@code{--dll-search-prefix=cyg}. + +@kindex --enable-auto-import +@item --enable-auto-import +Do sophisticated linking of @code{_symbol} to @code{__imp__symbol} for +DATA imports from DLLs, and create the necessary thunking symbols when +building the DLLs with those DATA exports. This generally will 'just +work' -- but sometimes you may see this message: + +"variable '<var>' can't be auto-imported. Please read the +documentation for ld's @code{--enable-auto-import} for details." + +This message occurs when some (sub)expression accesses an address +ultimately given by the sum of two constants (Win32 import tables only +allow one). Instances where this may occur include accesses to member +fields of struct variables imported from a DLL, as well as using a +constant index into an array variable imported from a DLL. Any +multiword variable (arrays, structs, long long, etc) may trigger +this error condition. However, regardless of the exact data type +of the offending exported variable, ld will always detect it, issue +the warning, and exit. + +There are several ways to address this difficulty, regardless of the +data type of the exported variable: + +One solution is to force one of the 'constants' to be a variable -- +that is, unknown and un-optimizable at compile time. For arrays, +there are two possibilities: a) make the indexee (the array's address) +a variable, or b) make the 'constant' index a variable. Thus: + +@example +extern type extern_array[]; +extern_array[1] --> + @{ volatile type *t=extern_array; t[1] @} +@end example + +or + +@example +extern type extern_array[]; +extern_array[1] --> + @{ volatile int t=1; extern_array[t] @} +@end example + +For structs (and most other multiword data types) the only option +is to make the struct itself (or the long long, or the ...) variable: + +@example +extern struct s extern_struct; +extern_struct.field --> + @{ volatile struct s *t=&extern_struct; t->field @} +@end example + +or + +@example +extern long long extern_ll; +extern_ll --> + @{ volatile long long * local_ll=&extern_ll; *local_ll @} +@end example + +A second method of dealing with this difficulty is to abandon +'auto-import' for the offending symbol and mark it with +@code{__declspec(dllimport)}. However, in practice that +requires using compile-time #defines to indicate whether you are +building a DLL, building client code that will link to the DLL, or +merely building/linking to a static library. In making the choice +between the various methods of resolving the 'direct address with +constant offset' problem, you should consider typical real-world usage: + +Original: +@example +--foo.h +extern int arr[]; +--foo.c +#include "foo.h" +void main(int argc, char **argv)@{ + printf("%d\n",arr[1]); +@} +@end example + +Solution 1: +@example +--foo.h +extern int arr[]; +--foo.c +#include "foo.h" +void main(int argc, char **argv)@{ + /* This workaround is for win32 and cygwin; do not "optimize" */ + volatile int *parr = arr; + printf("%d\n",parr[1]); +@} +@end example + +Solution 2: +@example +--foo.h +/* Note: auto-export is assumed (no __declspec(dllexport)) */ +#if (defined(_WIN32) || defined(__CYGWIN__)) && \ + !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC)) +#define FOO_IMPORT __declspec(dllimport) +#else +#define FOO_IMPORT +#endif +extern FOO_IMPORT int arr[]; +--foo.c +#include "foo.h" +void main(int argc, char **argv)@{ + printf("%d\n",arr[1]); +@} +@end example + +A third way to avoid this problem is to re-code your +library to use a functional interface rather than a data interface +for the offending variables (e.g. set_foo() and get_foo() accessor +functions). + +@kindex --disable-auto-import +@item --disable-auto-import +Do not attempt to do sophisticalted linking of @code{_symbol} to +@code{__imp__symbol} for DATA imports from DLLs. + +@kindex --enable-extra-pe-debug +@item --enable-extra-pe-debug +Show additional debug info related to auto-import symbol thunking. + @kindex --section-alignment @item --section-alignment Sets the section alignment. Sections in memory will always begin at @@ -1586,7 +1881,7 @@ addresses which are a multiple of this number. Defaults to 0x1000. @item --stack @var{reserve} @itemx --stack @var{reserve},@var{commit} Specify the amount of memory to reserve (and optionally commit) to be -used as stack for this program. The default is 32Mb reserved, 4K +used as stack for this program. The default is 2Mb reserved, 4K committed. @kindex --subsystem @@ -1600,11 +1895,15 @@ subsystem version also. @end table +@c man end + @ifset UsesEnvVars @node Environment @section Environment Variables -You can change the behavior of @code{ld} with the environment variables +@c man begin ENVIRONMENT + +You can change the behavior of @command{ld} with the environment variables @code{GNUTARGET}, @code{LDEMULATION}, and @code{COLLECT_NO_DEMANGLE}. @kindex GNUTARGET @@ -1612,7 +1911,7 @@ You can change the behavior of @code{ld} with the environment variables @code{GNUTARGET} determines the input-file object format if you don't use @samp{-b} (or its synonym @samp{--format}). Its value should be one of the BFD names for an input format (@pxref{BFD}). If there is no -@code{GNUTARGET} in the environment, @code{ld} uses the natural format +@code{GNUTARGET} in the environment, @command{ld} uses the natural format of the target. If @code{GNUTARGET} is set to @code{default} then BFD attempts to discover the input format by examining binary input files; this method often succeeds, but there are potential ambiguities, since @@ -1631,7 +1930,6 @@ available emulations with the @samp{--verbose} or @samp{-V} options. If the @samp{-m} option is not used, and the @code{LDEMULATION} environment variable is not defined, the default emulation depends upon how the linker was configured. -@end ifset @kindex COLLECT_NO_DEMANGLE @cindex demangling, default @@ -1642,6 +1940,9 @@ a similar fashion by the @code{gcc} linker wrapper program. The default may be overridden by the @samp{--demangle} and @samp{--no-demangle} options. +@c man end +@end ifset + @node Scripts @chapter Linker Scripts @@ -1883,7 +2184,7 @@ Several linker script commands deal with files. @cindex including a linker script Include the linker script @var{filename} at this point. The file will be searched for in the current directory, and in any directory specified -with the @code{-L} option. You can nest calls to @code{INCLUDE} up to +with the @option{-L} option. You can nest calls to @code{INCLUDE} up to 10 levels deep. @item INPUT(@var{file}, @var{file}, @dots{}) @@ -1907,7 +2208,7 @@ it is not found, the linker will search through the archive library search path. See the description of @samp{-L} in @ref{Options,,Command Line Options}. -If you use @samp{INPUT (-l@var{file})}, @code{ld} will transform the +If you use @samp{INPUT (-l@var{file})}, @command{ld} will transform the name to @code{lib@var{file}.a}, as with the command line argument @samp{-l}. @@ -1942,7 +2243,7 @@ output file other than the usual default of @file{a.out}. @cindex archive search path in linker script @cindex search path in linker script The @code{SEARCH_DIR} command adds @var{path} to the list of paths where -@code{ld} looks for archive libraries. Using +@command{ld} looks for archive libraries. Using @code{SEARCH_DIR(@var{path})} is exactly like using @samp{-L @var{path}} on the command line (@pxref{Options,,Command Line Options}). If both are used, then the linker will search both paths. Paths specified using @@ -2030,13 +2331,20 @@ command has the same effect as the @samp{-u} command-line option. @kindex FORCE_COMMON_ALLOCATION @cindex common allocation in linker script This command has the same effect as the @samp{-d} command-line option: -to make @code{ld} assign space to common symbols even if a relocatable +to make @command{ld} assign space to common symbols even if a relocatable output file is specified (@samp{-r}). +@item INHIBIT_COMMON_ALLOCATION +@kindex INHIBIT_COMMON_ALLOCATION +@cindex common allocation in linker script +This command has the same effect as the @samp{--no-define-common} +command-line option: to make @code{ld} omit the assignment of addresses +to common symbols even for a non-relocatable output file. + @item NOCROSSREFS(@var{section} @var{section} @dots{}) @kindex NOCROSSREFS(@var{sections}) @cindex cross references -This command may be used to tell @code{ld} to issue an error about any +This command may be used to tell @command{ld} to issue an error about any references among certain output sections. In certain types of programs, particularly on embedded systems when @@ -2046,7 +2354,7 @@ errors. For example, it would be an error if code in one section called a function defined in the other section. The @code{NOCROSSREFS} command takes a list of output section names. If -@code{ld} detects any cross references between the sections, it reports +@command{ld} detects any cross references between the sections, it reports an error and returns a non-zero exit status. Note that the @code{NOCROSSREFS} command uses output section names, not input section names. @@ -2374,7 +2682,8 @@ There are two ways to include more than one section: @noindent The difference between these is the order in which the @samp{.text} and @samp{.rdata} input sections will appear in the output section. In the -first example, they will be intermingled. In the second example, all +first example, they will be intermingled, appearing in the same order as +they are found in the linker input. In the second example, all @samp{.text} input sections will appear first, followed by all @samp{.rdata} input sections. @@ -2615,16 +2924,16 @@ You may use the @code{FILL} command to set the fill pattern for the current section. It is followed by an expression in parentheses. Any otherwise unspecified regions of memory within the section (for example, gaps left due to the required alignment of input sections) are filled -with the two least significant bytes of the expression, repeated as +with the four least significant bytes of the expression, repeated as necessary. A @code{FILL} statement covers memory locations after the point at which it occurs in the section definition; by including more than one @code{FILL} statement, you can have different fill patterns in different parts of an output section. This example shows how to fill unspecified regions of memory with the -value @samp{0x9090}: +value @samp{0x90}: @smallexample -FILL(0x9090) +FILL(0x90909090) @end smallexample The @code{FILL} command is similar to the @samp{=@var{fillexp}} output @@ -2910,7 +3219,7 @@ You can set the fill pattern for an entire section by using @samp{=@var{fillexp}}. @var{fillexp} is an expression (@pxref{Expressions}). Any otherwise unspecified regions of memory within the output section (for example, gaps left due to the required -alignment of input sections) will be filled with the two least +alignment of input sections) will be filled with the four least significant bytes of the value, repeated as necessary. You can also change the fill value with a @code{FILL} command in the @@ -2919,7 +3228,7 @@ output section commands; see @ref{Output Section Data}. Here is a simple example: @smallexample @group -SECTIONS @{ .text : @{ *(.text) @} =0x9090 @} +SECTIONS @{ .text : @{ *(.text) @} =0x90909090 @} @end group @end smallexample @@ -3378,6 +3687,15 @@ they might suggest to the person reading them. The @samp{2.0} version could just as well have appeared in between @samp{1.1} and @samp{1.2}. However, this would be a confusing way to write a version script. +Node name can be omited, provided it is the only version node +in the version script. Such version script doesn't assign any versions to +symbols, only selects which symbols will be globally visible out and which +won't. + +@smallexample +@{ global: foo; bar; local: *; @} +@end smallexample + When you link an application against a shared library that has versioned symbols, the application itself knows which version of each symbol it requires, and it also knows which version nodes it needs from each @@ -3446,6 +3764,17 @@ within the shared library, you can use the aliases of convenience (i.e. @samp{old_foo}), or you can use the @samp{.symver} directive to specifically bind to an external version of the function in question. +You can also specify the language in the version script: + +@smallexample +VERSION extern "lang" @{ version-script-commands @} +@end smallexample + +The supported @samp{lang}s are @samp{C}, @samp{C++}, and @samp{Java}. +The linker will iterate over the list of symbols at the link time and +demangle them according to @samp{lang} before matching them to the +patterns specified in @samp{version-script-commands}. + @node Expressions @section Expressions in Linker Scripts @cindex expressions @@ -3551,7 +3880,7 @@ SECTIONS file2(.text) . += 1000; file3(.text) - @} = 0x1234; + @} = 0x12345678; @} @end smallexample @noindent @@ -3559,7 +3888,7 @@ In the previous example, the @samp{.text} section from @file{file1} is located at the beginning of the output section @samp{output}. It is followed by a 1000 byte gap. Then the @samp{.text} section from @file{file2} appears, also with a 1000 byte gap following before the -@samp{.text} section from @file{file3}. The notation @samp{= 0x1234} +@samp{.text} section from @file{file3}. The notation @samp{= 0x12345678} specifies what data to write in the gaps (@pxref{Output Section Fill}). @cindex dot inside sections @@ -3937,8 +4266,8 @@ read. This can affect archive searching. @chapter Machine Dependent Features @cindex machine dependencies -@code{ld} has additional features on some platforms; the following -sections describe them. Machines where @code{ld} has no additional +@command{ld} has additional features on some platforms; the following +sections describe them. Machines where @command{ld} has no additional functionality are not listed. @menu @@ -3946,8 +4275,11 @@ functionality are not listed. * i960:: @code{ld} and the Intel 960 family * ARM:: @code{ld} and the ARM family * HPPA ELF32:: @code{ld} and HPPA 32-bit ELF +@ifset MMIX +* MMIX:: @code{ld} and MMIX +@end ifset @ifset TICOFF -* TI COFF:: @code{ld} and TI COFF +* TI COFF:: @command{ld} and TI COFF @end ifset @end menu @end ifset @@ -3960,16 +4292,16 @@ functionality are not listed. @end ifclear @node H8/300 -@section @code{ld} and the H8/300 +@section @command{ld} and the H8/300 @cindex H8/300 support -For the H8/300, @code{ld} can perform these global optimizations when +For the H8/300, @command{ld} can perform these global optimizations when you specify the @samp{--relax} command-line option. @table @emph @cindex relaxing on H8/300 @item relaxing address modes -@code{ld} finds all @code{jsr} and @code{jmp} instructions whose +@command{ld} finds all @code{jsr} and @code{jmp} instructions whose targets are within eight bits, and turns them into eight-bit program-counter relative @code{bsr} and @code{bra} instructions, respectively. @@ -3977,7 +4309,7 @@ respectively. @cindex synthesizing on H8/300 @item synthesizing instructions @c FIXME: specifically mov.b, or any mov instructions really? -@code{ld} finds all @code{mov.b} instructions which use the +@command{ld} finds all @code{mov.b} instructions which use the sixteen-bit absolute address form, but refer to the top page of memory, and changes them to use the eight-bit address form. (That is: the linker turns @samp{mov.b @code{@@}@var{aa}:16} into @@ -3995,9 +4327,9 @@ top page of memory). @c This stuff is pointless to say unless you're especially concerned @c with Hitachi chips; don't enable it for generic case, please. @node Hitachi -@chapter @code{ld} and other Hitachi chips +@chapter @command{ld} and other Hitachi chips -@code{ld} also supports the H8/300H, the H8/500, and the Hitachi SH. No +@command{ld} also supports the H8/300H, the H8/500, and the Hitachi SH. No special features, commands, or command-line options are required for these chips. @end ifset @@ -4009,7 +4341,7 @@ these chips. @end ifclear @node i960 -@section @code{ld} and the Intel 960 family +@section @command{ld} and the Intel 960 family @cindex i960 support @@ -4021,7 +4353,7 @@ linker's search strategy for archive libraries, to support the use of libraries specific to each particular architecture, by including in the search loop names suffixed with the string identifying the architecture. -For example, if your @code{ld} command line included @w{@samp{-ACA}} as +For example, if your @command{ld} command line included @w{@samp{-ACA}} as well as @w{@samp{-ltry}}, the linker would look (in its built-in search paths, and in any paths you specify with @samp{-L}) for a library with the names @@ -4044,13 +4376,13 @@ the 960 architecture family allows combination of target architectures; each use will add another pair of name variants to search for when @w{@samp{-l}} specifies a library. -@cindex @code{--relax} on i960 +@cindex @option{--relax} on i960 @cindex relaxing on i960 -@code{ld} supports the @samp{--relax} option for the i960 family. If -you specify @samp{--relax}, @code{ld} finds all @code{balx} and +@command{ld} supports the @samp{--relax} option for the i960 family. If +you specify @samp{--relax}, @command{ld} finds all @code{balx} and @code{calx} instructions whose targets are within 24 bits, and turns them into 24-bit program-counter relative @code{bal} and @code{cal} -instructions, respectively. @code{ld} also turns @code{cal} +instructions, respectively. @command{ld} also turns @code{cal} instructions into @code{bal} instructions when it determines that the target subroutine is a leaf routine (that is, the target subroutine does not itself call any subroutines). @@ -4065,11 +4397,11 @@ not itself call any subroutines). @end ifclear @node ARM -@section @code{ld}'s support for interworking between ARM and Thumb code +@section @command{ld}'s support for interworking between ARM and Thumb code @cindex ARM interworking support @kindex --support-old-code -For the ARM, @code{ld} will generate code stubs to allow functions calls +For the ARM, @command{ld} will generate code stubs to allow functions calls betweem ARM and Thumb code. These stubs only work with code that has been compiled and assembled with the @samp{-mthumb-interwork} command line option. If it is necessary to link with old ARM object files or @@ -4090,18 +4422,18 @@ branched to using a BX instruction, and the program will start executing in Thumb mode straight away. @node HPPA ELF32 -@section @code{ld} and HPPA 32-bit ELF support +@section @command{ld} and HPPA 32-bit ELF support @cindex HPPA multiple sub-space stubs @kindex --multi-subspace -When generating a shared library, @code{ld} will by default generate +When generating a shared library, @command{ld} will by default generate import stubs suitable for use with a single sub-space application. -The @samp{--multi-subspace} switch causes @code{ld} to generate export +The @samp{--multi-subspace} switch causes @command{ld} to generate export stubs, and different (larger) import stubs suitable for use with multiple sub-spaces. @cindex HPPA stub grouping @kindex --stub-group-size=@var{N} -Long branch stubs and import/export stubs are placed by @code{ld} in +Long branch stubs and import/export stubs are placed by @command{ld} in stub sections located between groups of input sections. @samp{--stub-group-size} specifies the maximum size of a group of input sections handled by one stub section. Since branch offsets are signed, @@ -4112,7 +4444,7 @@ prediction) that stub sections only serve one group of input sections. A negative value for @samp{N} chooses this scheme, ensuring that branches to stubs always use a negative offset. Two special values of @samp{N} are recognized, @samp{1} and @samp{-1}. These both instruct -@code{ld} to automatically size input section groups for the branch types +@command{ld} to automatically size input section groups for the branch types detected, with the same behaviour regarding stub placement as other positive or negative values of @samp{N} respectively. @@ -4121,15 +4453,41 @@ single input section larger than the group size specified will of course create a larger group (of one section). If input sections are too large, it may not be possible for a branch to reach its stub. +@ifset MMIX +@node MMIX +@section @code{ld} and MMIX +For MMIX, there is choice of generating @code{ELF} object files or +@code{mmo} object files when linking. The simulator @code{mmix} +understands the @code{mmo} format. The binutils @code{objcopy} utility +can translate between the two formats. + +There is one special section, the @samp{.MMIX.reg_contents} section. +Contents in this section is assumed to correspond to that of global +registers, and symbols referring to it are translated to special symbols, +equal to registers. In a final link, the start address of the +@samp{.MMIX.reg_contents} section corresponds to the first allocated +global register multiplied by 8. Register @code{$255} is not included in +this section; it is always set to the program entry, which is at the +symbol @code{Main} for @code{mmo} files. + +Symbols with the prefix @code{__.MMIX.start.}, for example +@code{__.MMIX.start..text} and @code{__.MMIX.start..data} are special; +there must be only one each, even if they are local. The default linker +script uses these to set the default start address of a section. + +Initial and trailing multiples of zero-valued 32-bit words in a section, +are left out from an mmo file. +@end ifset + @ifset TICOFF @node TI COFF -@section @code{ld}'s support for various TI COFF versions +@section @command{ld}'s support for various TI COFF versions @cindex TI COFF versions @kindex --format=@var{version} The @samp{--format} switch allows selection of one of the various TI COFF versions. The latest of this writing is 2; versions 0 and 1 are also supported. The TI COFF versions also vary in header byte-order -format; @code{ld} will read any version or byte order, but the output +format; @command{ld} will read any version or byte order, but the output header format depends on the default specified by the specific target. @end ifset @@ -4182,16 +4540,16 @@ conversion and during output. @xref{BFD information loss}. @node Reporting Bugs @chapter Reporting Bugs -@cindex bugs in @code{ld} -@cindex reporting bugs in @code{ld} +@cindex bugs in @command{ld} +@cindex reporting bugs in @command{ld} -Your bug reports play an essential role in making @code{ld} reliable. +Your bug reports play an essential role in making @command{ld} 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 @code{ld} +to help the entire community by making the next version of @command{ld} work better. Bug reports are your contribution to the maintenance of -@code{ld}. +@command{ld}. In order for a bug report to serve its purpose, you must include the information that enables us to fix the bug. @@ -4213,37 +4571,37 @@ If you are not sure whether you have found a bug, here are some guidelines: @cindex crash of linker @item If the linker gets a fatal signal, for any input whatever, that is a -@code{ld} bug. Reliable linkers never crash. +@command{ld} bug. Reliable linkers never crash. @cindex error on valid input @item -If @code{ld} produces an error message for valid input, that is a bug. +If @command{ld} produces an error message for valid input, that is a bug. @cindex invalid input @item -If @code{ld} does not produce an error message for invalid input, that +If @command{ld} does not produce an error message for invalid input, that may be a bug. In the general case, the linker can not verify that object files are correct. @item If you are an experienced user of linkers, your suggestions for -improvement of @code{ld} are welcome in any case. +improvement of @command{ld} are welcome in any case. @end itemize @node Bug Reporting @section How to report bugs @cindex bug reports -@cindex @code{ld} bugs, reporting +@cindex @command{ld} bugs, reporting A number of companies and individuals offer support for @sc{gnu} -products. If you obtained @code{ld} from a support organization, we +products. If you obtained @command{ld} 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 @sc{gnu} Emacs distribution. -Otherwise, send bug reports for @code{ld} to +Otherwise, send bug reports for @command{ld} to @samp{bug-binutils@@gnu.org}. The fundamental principle of reporting bugs usefully is this: @@ -4273,14 +4631,14 @@ To enable us to fix the bug, you should include all these things: @itemize @bullet @item -The version of @code{ld}. @code{ld} announces it if you start it with +The version of @command{ld}. @command{ld} announces it if you start it with the @samp{--version} argument. Without this, we will not know whether there is any point in looking for -the bug in the current version of @code{ld}. +the bug in the current version of @command{ld}. @item -Any patches you may have applied to the @code{ld} source, including any +Any patches you may have applied to the @command{ld} source, including any patches made to the @code{BFD} library. @item @@ -4288,7 +4646,7 @@ 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 @code{ld}---e.g. +What compiler (and its version) was used to compile @command{ld}---e.g. ``@code{gcc-2.7}''. @item @@ -4317,14 +4675,14 @@ how @code{gas} or @code{gcc} were configured. 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 @code{ld} gets a fatal signal, then we +Of course, if the bug is that @command{ld} 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. 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 @code{ld} is out of synch, or you have encountered a bug in the +copy of @command{ld} 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 @@ -4332,10 +4690,10 @@ 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 @code{ld} source, send us context +If you wish to suggest changes to the @command{ld} source, send us context diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} option. Always send diffs from the old file to the new file. -If you even discuss something in the @code{ld} source, refer to it by +If you even discuss something in the @command{ld} source, refer to it by context, not by line number. The line numbers in our development sources will not match those in your @@ -4373,7 +4731,7 @@ 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 @code{ld} it is very hard to +Sometimes with a program as complicated as @command{ld} 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 @@ -4393,12 +4751,12 @@ things without first using the debugger to find the facts. @node MRI @appendix MRI Compatible Script Files @cindex MRI compatibility -To aid users making the transition to @sc{gnu} @code{ld} from the MRI -linker, @code{ld} can use MRI compatible linker scripts as an +To aid users making the transition to @sc{gnu} @command{ld} from the MRI +linker, @command{ld} can use MRI compatible linker scripts as an alternative to the more general-purpose linker scripting language described in @ref{Scripts}. MRI compatible linker scripts have a much simpler command set than the scripting language otherwise used with -@code{ld}. @sc{gnu} @code{ld} supports the most commonly used MRI +@command{ld}. @sc{gnu} @command{ld} supports the most commonly used MRI linker commands; these commands are described here. In general, MRI scripts aren't of much use with the @code{a.out} object @@ -4411,7 +4769,7 @@ You can specify a file containing an MRI-compatible script using the Each command in an MRI-compatible script occupies its own line; each command line starts with the keyword that identifies the command (though blank lines are also allowed for punctuation). If a line of an -MRI-compatible script begins with an unrecognized keyword, @code{ld} +MRI-compatible script begins with an unrecognized keyword, @command{ld} issues a warning message, but continues processing the script. Lines beginning with @samp{*} are comments. @@ -4424,7 +4782,7 @@ The following list shows only the upper-case form of each command. @cindex @code{ABSOLUTE} (MRI) @item ABSOLUTE @var{secname} @itemx ABSOLUTE @var{secname}, @var{secname}, @dots{} @var{secname} -Normally, @code{ld} includes in the output file all sections from all +Normally, @command{ld} includes in the output file all sections from all the input files. However, in an MRI-compatible script, you can use the @code{ABSOLUTE} command to restrict the sections that will be present in your output program. If the @code{ABSOLUTE} command is used at all in a @@ -4479,7 +4837,7 @@ COFF (the @samp{coff-m68k} variant in BFD), if @var{output-format} is @cindex @code{LIST} (MRI) @item LIST @var{anything}@dots{} Print (to the standard output file) a link map, as produced by the -@code{ld} command-line option @samp{-M}. +@command{ld} command-line option @samp{-M}. The keyword @code{LIST} may be followed by anything on the same line, with no change in its effect. @@ -4488,19 +4846,19 @@ same line, with no change in its effect. @item LOAD @var{filename} @itemx LOAD @var{filename}, @var{filename}, @dots{} @var{filename} Include one or more object file @var{filename} in the link; this has the -same effect as specifying @var{filename} directly on the @code{ld} +same effect as specifying @var{filename} directly on the @command{ld} command line. @cindex @code{NAME} (MRI) @item NAME @var{output-name} -@var{output-name} is the name for the program produced by @code{ld}; the +@var{output-name} is the name for the program produced by @command{ld}; the MRI-compatible command @code{NAME} is equivalent to the command-line option @samp{-o} or the general script language command @code{OUTPUT}. @cindex @code{ORDER} (MRI) @item ORDER @var{secname}, @var{secname}, @dots{} @var{secname} @itemx ORDER @var{secname} @var{secname} @var{secname} -Normally, @code{ld} orders the sections in its output file in the +Normally, @command{ld} orders the sections in its output file in the order in which they first appear in the input files. In an MRI-compatible script, you can override this ordering with the @code{ORDER} command. The sections you list with @code{ORDER} will appear first in your output @@ -4910,5 +5268,3 @@ to permit their use in free software. @contents @bye - - |