FreeBSD 4.x crash system

[Jason Morgan]

On Sat, Aug 20, 2005 at 02:35:35PM +0200, Vincent Blondel wrote:
> 
> Hi,
> 
> System : FreeBSD 4.10-RELEASE-p2
> Host : Tyan Thunder K7X (S2468GN)
> Cpu  : 2 * Athlon MP 1800+
> Memory : 2 * 512Mb DDR-266 Memory
> Adaptec 5400s SCSI RAID Controller
> 
> I got for the second time, this week, a system crash with my FreeBSD server. You
> can find below what I get on the screen but I don't understand all what it means.
> I just see there was a problem with the process imapd ( previous time I got a
> segmentation fault with apache 1.3 )
> 
> fault code           = supervisor read, page not present
> instruction pointer  = 0x8:0xc02a3e90
> stack pointer        = 0x10:0xe3b22a10
> frame pointer        = 0x10:0xe3b22a14
> code segment         = base 0x10, limit 0xfffff, type 0x1b
>                      = DPL 0, press 1, def32 1, gran 1
> processor eflags     = interrupt enabled, resume, IOPL = 0
> current process      = 76856 (imapd)
> interrupt mask       = none <- SMP: xxx
>       kernel : type 12 trap, code=0
> db>
> 
> I also remarked the keyboard focused on a process with 'db>'. What is this and what can
> I do with it. I tried 'exit' 'quit' 'bye' but all these statements don't do anything so I
> just pressed on button 'Reset' and rebooted the machine.
> 
> Before starting the machine I checked the hardware by running 'memtest' during 6 hours and
> no errors were found. This seems to point the problem with my FreeBSD installation better
> than a hardware ( example memory ) error.
> 
> I also don't pretend my system is compiled with the best method. I remember ( this is
> now a log time ago ... ) I compiled lot of things with '-O2 -pipe' ( except the
> kernel with '-O -pipe' ) but is this safe enough for an SMP system with FreeBSD 4.x ???
> 
> So can somebody explain me what does this mean and also if I have to configure
> something to make a dump file when I get an error. I suppose this will be
> easier to investigate the problem if I still have other system crash.
> 
> Regards
> Vincent.

Here's how to get a crash dump.

http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug.html

In the mean time, I suggest recompiling world and kernel without -O2 and 
-O.

Cheers,
Jason