From owner-freebsd-questions@FreeBSD.ORG Fri Nov 28 04:07:48 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id BF545106567A for ; Fri, 28 Nov 2008 04:07:48 +0000 (UTC) (envelope-from kris@FreeBSD.org) Received: from kennaway-macbookpro.local (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id 9A7C28FC19; Fri, 28 Nov 2008 04:07:48 +0000 (UTC) (envelope-from kris@FreeBSD.org) Message-ID: <492F41BF.4030208@FreeBSD.org> Date: Thu, 27 Nov 2008 16:56:31 -0800 From: Kris Kennaway User-Agent: Thunderbird 2.0.0.17 (Macintosh/20080914) MIME-Version: 1.0 To: Frank Solensky References: <1227635054.6253.16.camel@frank-laptop> In-Reply-To: <1227635054.6253.16.camel@frank-laptop> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions Subject: Re: Kernel crash before dumpon X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Nov 2008 04:07:48 -0000 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 Please file a PR to remove the outdated advice.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