From owner-freebsd-current@FreeBSD.ORG Fri Apr 27 22:29:41 2007 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 2B1D516A401 for ; Fri, 27 Apr 2007 22:29:41 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.freebsd.org (Postfix) with ESMTP id B37BE13C458 for ; Fri, 27 Apr 2007 22:29:40 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from phobos.samsco.home (phobos.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.8/8.13.8) with ESMTP id l3RMTace030041; Fri, 27 Apr 2007 16:29:37 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <46327950.7030900@samsco.org> Date: Fri, 27 Apr 2007 16:29:36 -0600 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.2pre) Gecko/20070111 SeaMonkey/1.1 MIME-Version: 1.0 To: Peter Jeremy References: <20070426204602.GA81382@keltia.freenix.fr> <20070427012401.GZ2445@obelix.dsto.defence.gov.au> <20070427013742.GA51877@troutmask.apl.washington.edu> <20070427014317.GA17436@xor.obsecurity.org> <20070427030017.GA52347@troutmask.apl.washington.edu> <20070427031124.GA18527@xor.obsecurity.org> <20070427180021.GA57409@xor.obsecurity.org> <20070427222116.GG840@turion.vk2pj.dyndns.org> In-Reply-To: <20070427222116.GG840@turion.vk2pj.dyndns.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (pooker.samsco.org [168.103.85.57]); Fri, 27 Apr 2007 16:29:37 -0600 (MDT) X-Spam-Status: No, score=-1.4 required=5.5 tests=ALL_TRUSTED autolearn=failed version=3.1.8 X-Spam-Checker-Version: SpamAssassin 3.1.8 (2007-02-13) on pooker.samsco.org Cc: freebsd-current@freebsd.org, Tom Cumming , Steve Kargl , Kris Kennaway Subject: Re: Panic on boot. How do I get a kernel dump. X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Apr 2007 22:29:41 -0000 Peter Jeremy wrote: > On 2007-Apr-27 14:00:21 -0400, Kris Kennaway wrote: >> On Fri, Apr 27, 2007 at 08:31:16AM -0700, Tom Cumming wrote: >>> One possibility is to hard code dumpdev in the kernel, then boot that >>> kernel. >> I don't know many different ways I can say "there is no way to do it". > > I think Tom is saying that he needs to do something that _used_ to be > possible. Normally the Project is careful to avoid regressions so > this was a surprise to me as well. (It looks like it's demise wasn't > clearly spelt out at the time). > > Since dumpdev is now intertwined with geom and the geom tasting is > quite late in the boot process, I agree that the current crashdump > code does not seem amenable to use early in the boot process. > > Having a kernel crash before it reaches userland is not unheard of. > Whilst it may be possible to debug this using DDB or remote GDB in > some cases, I can think of two cases where this is not practical: > 1) It is a production server that can't be left down for extended periods. > 2) It is a remote system without remote console access. > > Lets put the original question slightly differently: How can the > kernel state be saved if the kernel crashes before it's possible to > invoke dumpon(8)? IMHO, "there is no way to do it" is not a > satisfactory answer for the reasons above. > Implement network crashdumps. This involves writing a new, separate, stripped down network stack, dealing with network configuration headaches, etc. It it will address the problem, though, albeit with a lot of development effort and pain. Scott