Date: Fri, 26 Jan 2001 08:17:58 -0800 (PST) From: Rich Wales <richw@webcom.com> To: freebsd-stable@freebsd.org Subject: Can't get a crash dump?!? Message-ID: <20010126153344.35549.richw@wyattearp.stanford.edu>
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I'm running 4.2-STABLE (cvsup'ed on January 20) on a Pentium which I'm
using as a firewall/bridge at home.
For the most part, the system works well, but it crashes under a sus-
tained heavy network load with "panic: m_dup: bogus m_pkthdr.len".
I can produce this panic at will by trying to download a very large
file. However, I've been completely unable to get a crash dump.
I have "dumpdev" set in /etc/rc.conf, and the "swapon" command works
during startup. (The box has 24MB of RAM, and the swap partition is
over twice that big, so dumping should theoretically work.)
If I include "options DDB" in the kernel configuration, then the
system (eventually) panics and drops into DDB. I can do a trace and
other DDB commands, but nothing I've tried so far will cause a crash
dump to be written out. In particular, I've tried combinations of
panic
continue
call boot(0)
call boot(256) [ RB_DUMP flag value in <sys/reboot.h> ]
but the best I can manage to do is get a "page fault while in kernel
mode" panic and another DDB prompt.
If I don't include "options DDB", then when the system eventually
crashes, it goes haywire. Screenful after screenful of (presumably)
panic messages whiz by on the monitor, and then a bunch of random
color bars are displayed (as if video memory has been overwritten
with random junk?), and then it reboots.
I tried adding some "printf"s to dumpsys() (in kern/kern_shutdown.c),
in order to see why it wasn't dumping, but none of my extra messages
get printed -- suggesting that dumpsys() isn't even being called.
Any ideas?
Rich Wales richw@webcom.com http://www.webcom.com/richw/
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