Date: Wed, 2 Dec 1998 10:01:16 -0800 (PST) From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: dillon@apollo.backplane.com (Matthew Dillon) Cc: green@unixhelp.org, freebsd-current@FreeBSD.ORG Subject: Re: Crash dump howto? Message-ID: <199812021801.KAA55752@troutmask.apl.washington.edu> In-Reply-To: <199812021728.JAA17722@apollo.backplane.com> from Matthew Dillon at "Dec 2, 1998 9:28: 4 am"
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According to Matthew Dillon:
>
> :
> :So, the question remains how does one force a dump?
> :
> :--
> :Steve
>
> This is what we do:
>
> options DDB
I have this option, and can break to the debugger.
>
> And in /etc/rc.conf.local:
>
> dumpdev="/dev/sd0b"
>
> Make sure the dump device (typically primary swap) is at least as large
> as your main memory or the system will not be able to dump.
>
I have tried /dev/da0s1b, /dev/da1s1b, and /dev/da1b with appropriately
labelled disk. da0s1b is 500 MB in size and da1s1b is 700 MB in size.
I have 256 MB of main memory.
> If the system farts, it will break into the debugger on the
> serial console (make sure whatever you connect to the serial console is
> itself secure!). From the ddb> prompt you can usually 'panic'. Sometimes
> it takes a 'panic' followed by an extra return, but be careful not to
> interrupt the dump in-progress because a return will also abort that.
db>panic
panic: from debugger
mp_lock = 01000002; cpuid = 1; lapic.id = 00000000
boot() called on CPU #1
(da1:ahc0:0:2:0) SYNCHRONIZE CACHE. CDB: 35 0 0 0 0 0 0 0 0 0
(da1:ahc0:0:2:0) error code 0
dumping to dev 409, offset 907232
Fatal trap 12: page fault while in kernel mode
mp_lock = 01000003; cpuid = 1; lapic.id = 00000000
fault virtual address = 0x20
fault code = supervisor read, page not present
instruction pointer = 0x8:0x20
stack pointer = 0x10:0xf9232998
frame pointer = 0x10:0x0
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, def32, 1, gran 1
process eflags = interrupt enabled, resume, IOPL = 0
current process = 95350 (procmail)
interrupt mask = net tty bio cam <- SMP: XXX
kernel: type 12 trap, code = 0
Stopped at _Debugger+0x35: movb $0,_in_Debugger.98
db> panic
Reach for reset button.
> The debug monitor can also be used to do a simple stack backtrace, ps,
> and a few other things before you panic the machine. This can be useful
> if the dump fails to work.
I've provided strack traces. There are a few hundred processes.
The dump never seems to actually happen.
--
Steve
finger kargl@troutmask.apl.washington.edu
http://troutmask.apl.washington.edu/~clesceri/kargl.html
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