223 lines
8.0 KiB
Groff
223 lines
8.0 KiB
Groff
.\" 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. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. 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 February 2, 1996
|
|
.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 filesystems 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 filesystem
|
|
during the bootstrap process.
|
|
Either the root filesystem has been corrupted,
|
|
or the system is attempting to use the wrong device as root filesystem.
|
|
Usually, an alternate copy of the system binary or an alternate root
|
|
filesystem 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 filesystem 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 filesystem inconsistencies are detected.
|
|
The problem generally results from a failure to repair damaged filesystems
|
|
after a crash, hardware failures, or other condition that should not
|
|
normally occur.
|
|
A filesystem 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 gdb 1
|
|
with the
|
|
.Fl k
|
|
flag 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/ .
|
|
.Sh SEE ALSO
|
|
.Xr gdb 1 ,
|
|
.Xr dumpon 8 ,
|
|
.Xr reboot 8 ,
|
|
.Xr savecore 8
|
|
.Sh HISTORY
|
|
A
|
|
.Nm
|
|
man page first appeared in
|
|
.Fx 2.2 .
|