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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