FreeBSD 6.3 Panic

[Christopher Key]

Hello,

I've recently started getting kernel panics with a FreeBSD 6.3 machine, 
using a minimal i386 custom kernel.  I don't believe it's a hardware 
issue as they always seem to coincide with a crash on SqueezeCenter, 
apparently during heavy usage of the MySQL backend.

I'm unable to get a crash dump.  After the panic, all I get in the 
console is,


Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0x5c05df
fault code              = supervisor read, page not present
instruction pointer     = 0x20:0xc05bc0a0
stack pointer           = 0x28:0xe8c178e0
frame pointer           = 0x28:0xe8c178ec
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 50243 (perl)
trap number             = 12
panic: page fault
cpuid = 1
Uptime: 1d20h16m14s
Dumping 2021 MB (6 chunks)
  chunk 0: 1MB (142 pages) ... ok
  chunk 1: 2021MB (517262 pages)


and it then sits apparently indefinitely with no disk activity, and 
needs a hard reboot.


At startup, no dump is found,

Checking for core dump on /dev/mirror/gm0s1b...
savecore: no dumps found


I have "dumpdev=AUTO" in my rc.conf, which gives the message,

kernel dumps on /dev/mirror/gm0s1b
swapon: adding /dev/mirror/gm0s1b as swap device

Is using a gmirrored swap partition for a dump device supported?


Can anyone suggest what I should be doing to try to get a crash dump 
successfully to further diagnose this?  Is there anything else relevant 
I should post?


Regards,

Chris