Date: Tue, 20 Jan 2004 21:08:41 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: rwatson@FreeBSD.org Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/alpha support.s src/sys/i386/i386 swtch.s src/sys/kern kern_shutdown.c src/sys/sys systm.h Message-ID: <20040120.210841.22504092.imp@bsdimp.com> In-Reply-To: <Pine.NEB.3.96L.1040120221452.53972J-100000@fledge.watson.org> References: <200401210307.i0L37s7E060437@gw.catspoiler.org> <Pine.NEB.3.96L.1040120221452.53972J-100000@fledge.watson.org>
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In message: <Pine.NEB.3.96L.1040120221452.53972J-100000@fledge.watson.org>
Robert Watson <rwatson@FreeBSD.org> writes:
:
: On Tue, 20 Jan 2004, Don Lewis wrote:
:
: > It would be extremely helpful to preserve the panic message and
: > (optionally) the backtrace across the reboot. Crash dumps may not
: > always be possible for any number of reasons (swap smaller than RAM,
: > /var/crash too small or overflowing with previous crash dumps, crash
: > dump takes too long ...). This is especially true in cases where the
: > machine crashes and reboots unattended.
:
: Actually, I was having a very similar conversation with Bill Paul this
: afternoon. We were discussing dropping a copy of the kernel message
: buffer onto the header of swap space on panic, if possible, and then
: dropping them in /var/log/crash.log for management by newsyslog. Then the
: natural response to "My machine spontaneously reboots" becomes "Look for
: something recent in /var/log/crash.log", as opposed to "You'll need to
: enable crash dumps, set up a serial console", etc. It's also something we
: could turn on by default, as opposed to crash dumps, which would otherwise
: consume of alot of disk space.
I assume you are talking about reading them out of swap space on boot
so you'd see something like the following in your logs:
<date-time> foo: first reboot after kernel panic
<insert-panic-message-here>
Right? Then the message would be zeroed out, so you don't get it on a
normal reboot, right?
Warner
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