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diff --git a/share/man/man8/crash.8 b/share/man/man8/crash.8 new file mode 100644 index 0000000..3383a75 --- /dev/null +++ b/share/man/man8/crash.8 @@ -0,0 +1,216 @@ +.\" FreeBSD version Copyright (c) 1996 +.\" Mike Pritchard <mpp@FreeBSD.org>. All rights reserved. +.\" +.\" Adapted from share/man/man8/man8.hp300/crash.8 +.\" +.\" Copyright (c) 1990, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd July 23, 2011 +.Dt CRASH 8 +.Os +.Sh NAME +.Nm crash +.Nd FreeBSD system failures +.Sh DESCRIPTION +This section explains a bit about system crashes +and (very briefly) how to analyze crash dumps. +.Pp +When the system crashes voluntarily it prints a message of the form +.Bl -diag -offset indent +.It "panic: why i gave up the ghost" +.El +.Pp +on the console, and if dumps have been enabled (see +.Xr dumpon 8 ) , +takes a dump on a mass storage peripheral, +and then invokes an automatic reboot procedure as +described in +.Xr reboot 8 . +Unless some unexpected inconsistency is encountered in the state +of the file systems due to hardware or software failure, the system +will then resume multi-user operations. +.Pp +The system has a large number of internal consistency checks; if one +of these fails, then it will panic with a very short message indicating +which one failed. +In many instances, this will be the name of the routine which detected +the error, or a two-word description of the inconsistency. +A full understanding of most panic messages requires perusal of the +source code for the system. +.Pp +The most common cause of system failures is hardware failure, which +can reflect itself in different ways. +Here are the messages which +are most likely, with some hints as to causes. +Left unstated in all cases is the possibility that hardware or software +error produced the message in some unexpected way. +.Pp +.Bl -diag -compact +.It "cannot mount root" +This panic message results from a failure to mount the root file system +during the bootstrap process. +Either the root file system has been corrupted, +or the system is attempting to use the wrong device as root file system. +Usually, an alternate copy of the system binary or an alternate root +file system can be used to bring up the system to investigate. +Most often +this is done by the use of the boot floppy you used to install the system, +and then using the +.Dq fixit +floppy. +.Pp +.It "init: not found" +This is not a panic message, as reboots are likely to be futile. +Late in the bootstrap procedure, the system was unable to locate +and execute the initialization process, +.Xr init 8 . +The root file system is incorrect or has been corrupted, or the mode +or type of +.Pa /sbin/init +forbids execution or is totally missing. +.Pp +.It "ffs_realloccg: bad optim" +.It "ffs_valloc: dup alloc" +.It "ffs_alloccgblk: cyl groups corrupted" +.It "ffs_alloccg: map corrupted" +.It "blkfree: freeing free block" +.It "blkfree: freeing free frag" +.It "ifree: freeing free inode" +These panic messages are among those that may be produced +when file system inconsistencies are detected. +The problem generally results from a failure to repair damaged file systems +after a crash, hardware failures, or other condition that should not +normally occur. +A file system check will normally correct the problem. +.Pp +.It "timeout table full" +This really should not be a panic, but until the data structure +involved is made to be extensible, running out of entries causes a crash. +If this happens, make the timeout table bigger. +.Pp +.\" .It "trap type %d, code = %x, v = %x" +.\" An unexpected trap has occurred within the system; the trap types are: +.\" .Bl -column xxxx -offset indent +.\" 0 bus error +.\" 1 address error +.\" 2 illegal instruction +.\" 3 divide by zero +.\" .No 4\t Em chk No instruction +.\" .No 5\t Em trapv No instruction +.\" 6 privileged instruction +.\" 7 trace trap +.\" 8 MMU fault +.\" 9 simulated software interrupt +.\" 10 format error +.\" 11 FP coprocessor fault +.\" 12 coprocessor fault +.\" 13 simulated AST +.\" .El +.\" .Pp +.\" The favorite trap type in system crashes is trap type 8, +.\" indicating a wild reference. +.\" ``code'' (hex) is the concatenation of the +.\" MMU +.\" status register +.\" (see <hp300/cpu.h>) +.\" in the high 16 bits and the 68020 special status word +.\" (see the 68020 manual, page 6-17) +.\" in the low 16. +.\" ``v'' (hex) is the virtual address which caused the fault. +.\" Additionally, the kernel will dump about a screenful of semi-useful +.\" information. +.\" ``pid'' (decimal) is the process id of the process running at the +.\" time of the exception. +.\" Note that if we panic in an interrupt routine, +.\" this process may not be related to the panic. +.\" ``ps'' (hex) is the 68020 processor status register ``ps''. +.\" ``pc'' (hex) is the value of the program counter saved +.\" on the hardware exception frame. +.\" It may +.\" .Em not +.\" be the PC of the instruction causing the fault. +.\" ``sfc'' and ``dfc'' (hex) are the 68020 source/destination function codes. +.\" They should always be one. +.\" ``p0'' and ``p1'' are the +.\" VAX-like +.\" region registers. +.\" They are of the form: +.\" .Pp +.\" .Bd -ragged -offset indent +.\" <length> '@' <kernel VA> +.\" .Ed +.\" .Pp +.\" where both are in hex. +.\" Following these values are a dump of the processor registers (hex). +.\" Finally, is a dump of the stack (user/kernel) at the time of the offense. +.\" .Pp +.It "init died (signal #, exit #)" +The system initialization process has exited with the specified +signal number and exit code. +This is bad news, as no new users will then be able to log in. +Rebooting is the only fix, so the +system just does it right away. +.El +.Pp +That completes the list of panic types you are likely to see. +.Pp +If the system has been configured to take crash dumps (see +.Xr dumpon 8 ) , +then when it crashes it will write (or at least attempt to write) +an image of memory into the back end of the dump device, +usually the same as the primary swap +area. +After the system is rebooted, the program +.Xr savecore 8 +runs and preserves a copy of this core image and the current +system in a specified directory for later perusal. +See +.Xr savecore 8 +for details. +.Pp +To analyze a dump you should begin by running +.Xr kgdb 1 +on the system load image and core dump. +If the core image is the result of a panic, +the panic message is printed. +For more details consult the chapter on kernel debugging in +the +.%B "FreeBSD Developers' Handbook" +.Pq Pa http://www.freebsd.org/doc/en/books/developers-handbook/ . +.Sh SEE ALSO +.Xr kgdb 1 , +.Xr dumpon 8 , +.Xr reboot 8 , +.Xr savecore 8 +.Sh HISTORY +The +.Nm +manual page first appeared in +.Fx 2.2 . |
