Date: Fri, 30 Nov 2007 12:30:14 +1100 From: Antony Mawer <fbsd-stable@mawer.org> To: Jeremy Chadwick <koitsu@FreeBSD.org> Cc: freebsd-stable@freebsd.org Subject: swapon running before savecore (was Re: RELENG_6 kernel panic + savecore(8) problem) Message-ID: <474F67A6.6070306@mawer.org> In-Reply-To: <20071126023313.GA2376@eos.sc1.parodius.com> References: <20071107191611.GA1400@eos.sc1.parodius.com> <20071107232328.GA1678@eos.sc1.parodius.com> <20071126022136.GA1564@eos.sc1.parodius.com> <20071126023313.GA2376@eos.sc1.parodius.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 26/11/2007 1:33 PM, Jeremy Chadwick wrote: > On Sun, Nov 25, 2007 at 06:21:36PM -0800, Jeremy Chadwick wrote: >> I believe the problem is that /etc/rc.d/swap1 is being run before >> savecore. I'm guessing that swapon(8) actually destroys/clobbers the >> existing saved kernel panic/core data, thus one will never get a >> coredump in /var/crash. I believe some re-organisation of rcorder(8) >> arguments in the files is in order, but I don't know what should >> be changed to what. >> >> I'll submit a PR for the above, because IMHO that's a serious one. > > PR 118255 has been opened for this matter. > > http://www.freebsd.org/cgi/query-pr.cgi?pr=118255 There seems to be conflicting information about what constitutes the correct behaviour here. The original 4.4BSD "Unix System Manager's Manual (SMM)", found here: http://docs.freebsd.org/44doc/smm/02.config/paper-6.html Indicates the following (found under the "System dumps" heading): - Kernel dumps write from the end of swap and work backwards - The kernel uses swap from the front and works forward - This way it reduces the chance of swapping overwriting the dump during the boot process until savecore is run This somewhat more modern posting suggests that is still the case: http://unix.derkeiler.com/Mailing-Lists/FreeBSD/stable/2005-11/0703.html However the FreeBSD Developers' Handbook suggests a behaviour that does not match the current reality: http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug.html#EXTRACT-DUMP Can anyone speak with more authority on this...? --Antony
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?474F67A6.6070306>