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.\" $FreeBSD$ 38.\" 39.Dd February 2, 1996 40.Dt CRASH 8 41.Os FreeBSD 42.Sh NAME 43.Nm crash 44.Nd FreeBSD system failures 45.Sh DESCRIPTION 46This section explains a bit about system crashes 47and (very briefly) how to analyze crash dumps. 48.Pp 49When the system crashes voluntarily it prints a message of the form 50.Bd -ragged -offset indent 51panic: why i gave up the ghost 52.Ed 53.Pp 54on the console, and if dumps have been enabled (see 55.Xr dumpon 8 ) , 56takes a dump on a mass storage peripheral, 57and then invokes an automatic reboot procedure as 58described in 59.Xr reboot 8 . 60Unless some unexpected inconsistency is encountered in the state 61of the file systems due to hardware or software failure, the system 62will then resume multi-user operations. 63.Pp 64The system has a large number of internal consistency checks; if one 65of these fails, then it will panic with a very short message indicating 66which one failed. 67In many instances, this will be the name of the routine which detected 68the error, or a two-word description of the inconsistency. 69A full understanding of most panic messages requires perusal of the 70source code for the system. 71.Pp 72The most common cause of system failures is hardware failure, which 73can reflect itself in different ways. Here are the messages which 74are most likely, with some hints as to causes. 75Left unstated in all cases is the possibility that hardware or software 76error produced the message in some unexpected way. 77.Pp 78.Bl -tag -width Ds -compact 79.It Sy "cannot mount root" 80This panic message results from a failure to mount the root filesystem 81during the bootstrap process. 82Either the root filesystem has been corrupted, 83or the system is attempting to use the wrong device as root filesystem. 84Usually, an alternate copy of the system binary or an alternate root 85filesystem can be used to bring up the system to investigate. Most often 86this is done by the use of the boot floppy you used to install the system, 87and then using the "fixit" floppy. 88.Pp 89.It Sy "init: not found" 90This is not a panic message, as reboots are likely to be futile. 91Late in the bootstrap procedure, the system was unable to locate 92and execute the initialization process, 93.Xr init 8 . 94The root filesystem is incorrect or has been corrupted, or the mode 95or type of 96.Pa /sbin/init 97forbids execution or is totally missing. 98.Pp 99.Pp 100.It Sy "ffs_realloccg: bad optim" 101.It Sy "ffs_valloc: dup alloc" 102.It Sy "ffs_alloccgblk: cyl groups corrupted" 103.It Sy "ffs_alloccg: map corrupted" 104.It Sy "blkfree: freeing free block" 105.It Sy "blkfree: freeing free frag" 106.It Sy "ifree: freeing free inode" 107These panic messages are among those that may be produced 108when filesystem inconsistencies are detected. 109The problem generally results from a failure to repair damaged filesystems 110after a crash, hardware failures, or other condition that should not 111normally occur. 112A filesystem check will normally correct the problem. 113.Pp 114.It Sy "timeout table full" 115This really shouldn't be a panic, but until the data structure 116involved is made to be extensible, running out of entries causes a crash. 117If this happens, make the timeout table bigger. 118.Pp 119.\" .It Sy "trap type %d, code = %x, v = %x" 120.\" An unexpected trap has occurred within the system; the trap types are: 121.\" .Bl -column xxxx -offset indent 122.\" 0 bus error 123.\" 1 address error 124.\" 2 illegal instruction 125.\" 3 divide by zero 126.\" .No 4\t Em chk No instruction 127.\" .No 5\t Em trapv No instruction 128.\" 6 privileged instruction 129.\" 7 trace trap 130.\" 8 MMU fault 131.\" 9 simulated software interrupt 132.\" 10 format error 133.\" 11 FP coprocessor fault 134.\" 12 coprocessor fault 135.\" 13 simulated AST 136.\" .El 137.\" .Pp 138.\" The favorite trap type in system crashes is trap type 8, 139.\" indicating a wild reference. 140.\" ``code'' (hex) is the concatenation of the 141.\" MMU 142.\" status register 143.\" (see <hp300/cpu.h>) 144.\" in the high 16 bits and the 68020 special status word 145.\" (see the 68020 manual, page 6-17) 146.\" in the low 16. 147.\" ``v'' (hex) is the virtual address which caused the fault. 148.\" Additionally, the kernel will dump about a screenful of semi-useful 149.\" information. 150.\" ``pid'' (decimal) is the process id of the process running at the 151.\" time of the exception. 152.\" Note that if we panic in an interrupt routine, 153.\" this process may not be related to the panic. 154.\" ``ps'' (hex) is the 68020 processor status register ``ps''. 155.\" ``pc'' (hex) is the value of the program counter saved 156.\" on the hardware exception frame. 157.\" It may 158.\" .Em not 159.\" be the PC of the instruction causing the fault. 160.\" ``sfc'' and ``dfc'' (hex) are the 68020 source/destination function codes. 161.\" They should always be one. 162.\" ``p0'' and ``p1'' are the 163.\" VAX-like 164.\" region registers. 165.\" They are of the form: 166.\" .Pp 167.\" .Bd -ragged -offset indent 168.\" <length> '@' <kernel VA> 169.\" .Ed 170.\" .Pp 171.\" where both are in hex. 172.\" Following these values are a dump of the processor registers (hex). 173.\" Finally, is a dump of the stack (user/kernel) at the time of the offense. 174.\" .Pp 175.It Sy "init died (signal #, exit #)" 176The system initialization process has exited with the specified signal number and exit code. This is bad news, as no new 177users will then be able to log in. Rebooting is the only fix, so the 178system just does it right away. 179.El 180.Pp 181That completes the list of panic types you are likely to see. 182.Pp 183If the system has been configured to take crash dumps (see 184.Xr dumpon 8 ) , 185then when it crashes it will write (or at least attempt to write) 186an image of memory into the back end of the dump device, 187usually the same as the primary swap 188area. After the system is rebooted, the program 189.Xr savecore 8 190runs and preserves a copy of this core image and the current 191system in a specified directory for later perusal. See 192.Xr savecore 8 193for details. 194.Pp 195To analyze a dump you should begin by running 196.Xr gdb 1 197with the 198.Fl k 199flag on the system load image and core dump. 200If the core image is the result of a panic, 201the panic message is printed. 202For more details consult the chapter on kernel debugging in 203the 204.Fx 205handbook 206.Pq Pa http://www.FreeBSD.org . 207.Sh SEE ALSO 208.Xr gdb 1 , 209.Xr dumpon 8 , 210.Xr reboot 8 , 211.Xr savecore 8 212.Sh HISTORY 213A 214.Nm 215man page first appeared in 216.Fx 2.2 . 217