Date: Wed, 2 Dec 1998 09:28:04 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Steve Kargl <sgk@troutmask.apl.washington.edu> Cc: green@unixhelp.org (Brian Feldman), freebsd-current@FreeBSD.ORG Subject: Re: Crash dump howto? Message-ID: <199812021728.JAA17722@apollo.backplane.com> References: <199812021659.IAA41596@troutmask.apl.washington.edu>
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:
:I have sources from 2 days ago. I have version 1.74 of vfs_cluster.c
:which is alleged to have fixed the problem. It doesn't. My sources
:are cvsup'd from cvsup.freebsd.org.
:
:I can kill the system under heavy load with either and ELF or aout kernel.
:
:I can not get the system to produce a crash dump.
:
:So, the question remains how does one force a dump?
:
:--
:Steve
This is what we do:
options DDB
options COMCONSOLE # serial console vs normal console
options BREAK_TO_DEBUGGER #a BREAK on a comconsole goes to
#DDB, if available.
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.
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.
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.
Also make sure you are using a reasonably standardized /etc/rc that
properly savecore's the dumps, and that /var/crash is big enough to hold
the writeout (a bit more then the main memory size in free space must
be available).
-Matt
Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet
Communications & God knows what else.
<dillon@backplane.com> (Please include original email in any response)
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