1.\" FreeBSD version Copyright (c) 1996 2.\" Mike Pritchard <mpp@FreeBSD.org>. All rights reserved. 3.\" 4.\" Adapted from share/man/man8/man8.hp300/crash.8 5.\" 6.\" Copyright (c) 1990, 1991, 1993 7.\" The Regents of the University of California. All rights reserved. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the University of 20.\" California, Berkeley and its contributors. 21.\" 4. Neither the name of the University nor the names of its contributors 22.\" may be used to endorse or promote products derived from this software 23.\" without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35.\" SUCH DAMAGE. 36.\" 37.\" $FreeBSD: src/share/man/man8/crash.8,v 1.22 2005/06/30 13:01:44 hmp Exp $ 38.\" $DragonFly: src/share/man/man8/crash.8,v 1.9 2008/01/08 14:20:46 matthias Exp $ 39.\" 40.Dd January 8, 2007 41.Dt CRASH 8 42.Os 43.Sh NAME 44.Nm crash 45.Nd DragonFly system failures 46.Sh DESCRIPTION 47This section explains a bit about system crashes 48and (very briefly) how to analyze crash dumps. 49.Pp 50When the system crashes voluntarily it prints a message of the form 51.Bl -diag -offset indent 52.It "panic: why i gave up the ghost" 53.El 54.Pp 55on the console, and if dumps have been enabled (see 56.Xr dumpon 8 ) , 57takes a dump on a mass storage peripheral, 58and then invokes an automatic reboot procedure as 59described in 60.Xr reboot 8 . 61Unless some unexpected inconsistency is encountered in the state 62of the file systems due to hardware or software failure, the system 63will then resume multi-user operations. 64.Pp 65The system has a large number of internal consistency checks; if one 66of these fails, then it will panic with a very short message indicating 67which one failed. 68In many instances, this will be the name of the routine which detected 69the error, or a two-word description of the inconsistency. 70A full understanding of most panic messages requires perusal of the 71source code for the system. 72.Pp 73The most common cause of system failures is hardware failure, which 74can reflect itself in different ways. 75Here are the messages which 76are most likely, with some hints as to causes. 77Left unstated in all cases is the possibility that hardware or software 78error produced the message in some unexpected way. 79.Pp 80.Bl -diag -compact 81.It "cannot mount root" 82This panic message results from a failure to mount the root file system 83during the bootstrap process. 84Either the root file system has been corrupted, 85or the system is attempting to use the wrong device as root file system. 86Usually, an alternate copy of the system binary or an alternate root 87file system can be used to bring up the system to investigate. 88Most often this is done using the 89.Dx 90.Dq LiveCD . 91.Pp 92.It "init: not found" 93This is not a panic message, as reboots are likely to be futile. 94Late in the bootstrap procedure, the system was unable to locate 95and execute the initialization process, 96.Xr init 8 . 97The root file system is incorrect or has been corrupted, or the mode 98or type of 99.Pa /sbin/init 100forbids execution or is totally missing. 101.Pp 102.It "ffs_realloccg: bad optim" 103.It "ffs_valloc: dup alloc" 104.It "ffs_alloccgblk: cyl groups corrupted" 105.It "ffs_alloccg: map corrupted" 106.It "blkfree: freeing free block" 107.It "blkfree: freeing free frag" 108.It "ifree: freeing free inode" 109These panic messages are among those that may be produced 110when file system inconsistencies are detected. 111The problem generally results from a failure to repair damaged file systems 112after a crash, hardware failures, or other condition that should not 113normally occur. 114A file system check will normally correct the problem. 115.Pp 116.It "timeout table full" 117This really should not be a panic, but until the data structure 118involved is made to be extensible, running out of entries causes a crash. 119If this happens, make the timeout table bigger. 120.Pp 121.It "init died (signal #, exit #)" 122The system initialization process has exited with the specified 123signal number and exit code. 124This is bad news, as no new users will then be able to log in. 125Rebooting is the only fix, so the 126system just does it right away. 127.El 128.Pp 129That completes the list of panic types you are likely to see. 130.Pp 131If the system has been configured to take crash dumps (see 132.Xr dumpon 8 ) , 133then when it crashes it will write (or at least attempt to write) 134an image of memory into the back end of the dump device, 135usually the same as the primary swap 136area. 137After the system is rebooted, the program 138.Xr savecore 8 139runs and preserves a copy of this core image and the current 140system in a specified directory for later perusal. 141See 142.Xr savecore 8 143for details. 144.Pp 145To analyze a dump you should begin by running 146.Xr kgdb 1 147on the system load image and core dump. 148If the core image is the result of a panic, 149the panic message is printed. 150For more details consult the chapter on kernel debugging in 151the 152.%B "DragonFly Handbook" 153.Pq Pa http://www.dragonflybsd.org/docs/handbook/ . 154.Sh SEE ALSO 155.Xr kgdb 1 , 156.Xr dumpon 8 , 157.Xr reboot 8 , 158.Xr savecore 8 159.Sh HISTORY 160The 161.Nm 162manual page first appeared in 163.Fx 2.2 . 164