Date: Thu, 27 Nov 2008 16:56:31 -0800 From: Kris Kennaway <kris@FreeBSD.org> To: Frank Solensky <frank@solensky.org> Cc: freebsd-questions <freebsd-questions@freebsd.org> Subject: Re: Kernel crash before dumpon Message-ID: <492F41BF.4030208@FreeBSD.org> In-Reply-To: <1227635054.6253.16.camel@frank-laptop> References: <1227635054.6253.16.camel@frank-laptop>
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Frank Solensky wrote: > I'm trying to get a dump off a machine with a 7.1-beta2 kernel that's > been crashing during the boot process, following the instructions on > http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html#KERNELDEBUG-OBTAIN > I've recompiled the kernel with "-g" but no vmcore file appears so I'm > assuming that the crash occurs before dumpon is executed. > > The page includes the following suggestion on how I might be able to > proceed: > Alternatively, the dump device can be hard-coded via the > dump clause in the config(5) line of a kernel configuration > file. This approach is deprecated and should be used only > if a kernel is crashing before dumpon(8) can be executed. > > I tried adding > config dump "/dev/ad4s3b" > to the configuration file but that option appears to be no longer > supported: the config command gives an error message of: > root/dump/swap specification obsolete > > Is the paragraph above obsolete? If so, what's the preferred way to > collect the dump? Yes, it's obsolete. Please file a PR to remove the outdated advice. Unfortunately in FreeBSD 5 and later there is no way to dump prior to multi-user startup, because of how device discovery is now dynamic. You can still use other tools like ddb/remote gdb etc. Kris
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