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.\" 38.Dd February 2, 1996 39.Dt CRASH 8 i386 40.Os FreeBSD 41.Sh NAME 42.Nm crash 43.Nd FreeBSD system failures 44.Sh DESCRIPTION 45This section explains a bit about system crashes 46and (very briefly) how to analyze crash dumps. 47.Pp 48When the system crashes voluntarily it prints a message of the form 49.Bd -ragged -offset indent 50panic: why i gave up the ghost 51.Ed 52.Pp 53on the console, and if dumps have been enabled (see 54.Xr dumpon 8 ) , 55takes a dump on a mass storage peripheral, 56and then invokes an automatic reboot procedure as 57described in 58.Xr reboot 8 . 59Unless some unexpected inconsistency is encountered in the state 60of the file systems due to hardware or software failure, the system 61will then resume multi-user operations. 62.Pp 63The system has a large number of internal consistency checks; if one 64of these fails, then it will panic with a very short message indicating 65which one failed. 66In many instances, this will be the name of the routine which detected 67the error, or a two-word description of the inconsistency. 68A full understanding of most panic messages requires perusal of the 69source code for the system. 70.Pp 71The most common cause of system failures is hardware failure, which 72can reflect itself in different ways. Here are the messages which 73are most likely, with some hints as to causes. 74Left unstated in all cases is the possibility that hardware or software 75error produced the message in some unexpected way. 76.Pp 77.Bl -tag -width Ds -compact 78.It Sy "cannot mount root" 79This panic message results from a failure to mount the root filesystem 80during the bootstrap process. 81Either the root filesystem has been corrupted, 82or the system is attempting to use the wrong device as root filesystem. 83Usually, an alternate copy of the system binary or an alternate root 84filesystem can be used to bring up the system to investigate. Most often 85this is done by the use of the boot floppy you used to install the system, 86and then using the "fixit" floppy. 87.Pp 88.It Sy "init: not found" 89This is not a panic message, as reboots are likely to be futile. 90Late in the bootstrap procedure, the system was unable to locate 91and execute the initialization process, 92.Xr init 8 . 93The root filesystem is incorrect or has been corrupted, or the mode 94or type of 95.Pa /sbin/init 96forbids execution or is totally missing. 97.Pp 98.Pp 99.It Sy "ffs_realloccg: bad optim" 100.It Sy "ffs_valloc: dup alloc" 101.It Sy "ffs_alloccgblk: cyl groups corrupted" 102.It Sy "ffs_alloccg: map corrupted" 103.It Sy "blkfree: freeing free block" 104.It Sy "blkfree: freeing free frag" 105.It Sy "ifree: freeing free inode" 106These panic messages are among those that may be produced 107when filesystem inconsistencies are detected. 108The problem generally results from a failure to repair damaged filesystems 109after a crash, hardware failures, or other condition that should not 110normally occur. 111A filesystem check will normally correct the problem. 112.Pp 113.It Sy "timeout table full" 114This really shouldn't be a panic, but until the data structure 115involved is made to be extensible, running out of entries causes a crash. 116If this happens, make the timeout table bigger. 117.Pp 118.\" .It Sy "trap type %d, code = %x, v = %x" 119.\" An unexpected trap has occurred within the system; the trap types are: 120.\" .Bl -column xxxx -offset indent 121.\" 0 bus error 122.\" 1 address error 123.\" 2 illegal instruction 124.\" 3 divide by zero 125.\" .No 4\t Em chk No instruction 126.\" .No 5\t Em trapv No instruction 127.\" 6 privileged instruction 128.\" 7 trace trap 129.\" 8 MMU fault 130.\" 9 simulated software interrupt 131.\" 10 format error 132.\" 11 FP coprocessor fault 133.\" 12 coprocessor fault 134.\" 13 simulated AST 135.\" .El 136.\" .Pp 137.\" The favorite trap type in system crashes is trap type 8, 138.\" indicating a wild reference. 139.\" ``code'' (hex) is the concatenation of the 140.\" MMU 141.\" status register 142.\" (see <hp300/cpu.h>) 143.\" in the high 16 bits and the 68020 special status word 144.\" (see the 68020 manual, page 6-17) 145.\" in the low 16. 146.\" ``v'' (hex) is the virtual address which caused the fault. 147.\" Additionally, the kernel will dump about a screenful of semi-useful 148.\" information. 149.\" ``pid'' (decimal) is the process id of the process running at the 150.\" time of the exception. 151.\" Note that if we panic in an interrupt routine, 152.\" this process may not be related to the panic. 153.\" ``ps'' (hex) is the 68020 processor status register ``ps''. 154.\" ``pc'' (hex) is the value of the program counter saved 155.\" on the hardware exception frame. 156.\" It may 157.\" .Em not 158.\" be the PC of the instruction causing the fault. 159.\" ``sfc'' and ``dfc'' (hex) are the 68020 source/destination function codes. 160.\" They should always be one. 161.\" ``p0'' and ``p1'' are the 162.\" VAX-like 163.\" region registers. 164.\" They are of the form: 165.\" .Pp 166.\" .Bd -ragged -offset indent 167.\" <length> '@' <kernel VA> 168.\" .Ed 169.\" .Pp 170.\" where both are in hex. 171.\" Following these values are a dump of the processor registers (hex). 172.\" Finally, is a dump of the stack (user/kernel) at the time of the offense. 173.\" .Pp 174.It Sy "init died (signal #, exit #)" 175The system initialization process has exited with the specified signal number and exit code. This is bad news, as no new 176users will then be able to log in. Rebooting is the only fix, so the 177system just does it right away. 178.Pp 179That completes the list of panic types you are likely to see. 180.Pp 181If the system has been configured to take crash dumps (see 182.Xr dumpon 8 ) , 183then when it crashes it will write (or at least attempt to write) 184an image of memory into the back end of the dump device, 185usually the same as the primary swap 186area. After the system is rebooted, the program 187.Xr savecore 8 188runs and preserves a copy of this core image and the current 189system in a specified directory for later perusal. See 190.Xr savecore 8 191for details. 192.Pp 193To analyze a dump you should begin by running 194.Xr gdb 1 195with the 196.Fl k 197flag on the system load image and core dump. 198If the core image is the result of a panic, 199the panic message is printed. 200For more details consult the chapter on kernel debugging in 201the FreeBSD handbook (http://www.freebsd.org). 202.Sh SEE ALSO 203.Xr gdb 1 , 204.Xr dumpon 8 , 205.Xr savecore 8 , 206.Xr reboot 8 207.Sh HISTORY 208A 209.Nm crash 210man page first appeared in 211.Fx 2.2 . 212