From owner-svn-src-head@FreeBSD.ORG Tue Sep 28 19:51:26 2010 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1EBA5106566B; Tue, 28 Sep 2010 19:51:26 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id DF3678FC1B; Tue, 28 Sep 2010 19:51:25 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 81FB446B66; Tue, 28 Sep 2010 15:51:25 -0400 (EDT) Received: from jhbbsd.localnet (smtp.hudson-trading.com [209.249.190.9]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 7AC908A04E; Tue, 28 Sep 2010 15:51:24 -0400 (EDT) From: John Baldwin To: Pawel Jakub Dawidek Date: Tue, 28 Sep 2010 15:50:29 -0400 User-Agent: KMail/1.13.5 (FreeBSD/7.3-CBSD-20100819; KDE/4.4.5; amd64; ; ) References: <20100922222441.00002f27@unknown> <201009281504.12236.jhb@freebsd.org> <20100928193611.GD2224@garage.freebsd.pl> In-Reply-To: <20100928193611.GD2224@garage.freebsd.pl> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201009281550.29825.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Tue, 28 Sep 2010 15:51:24 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.95.1 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.6 required=4.2 tests=AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: bruce@cran.org.uk, src-committers@freebsd.org, Ken Smith , svn-src-all@freebsd.org, avg@freebsd.org, gavin@freebsd.org, svn-src-head@freebsd.org, "M. Warner Losh" Subject: Re: svn commit: r212964 - head/sys/kern X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Sep 2010 19:51:26 -0000 On Tuesday, September 28, 2010 3:36:11 pm Pawel Jakub Dawidek wrote: > On Tue, Sep 28, 2010 at 03:04:11PM -0400, John Baldwin wrote: > > I'm suggesting they provide us the core.txt.X file, not the full minidump. > > A developer could then ask them to run specific commands from a subsequent > > kgdb session to obtain more details. > > But you still will have your kernel memory dumped to disk. This is > probably not a problem for most of the users, though. I think that set of users is sufficiently small that they could choose a non-default setting. > > > You can always ask user to add this one-line to rc.conf to turn > > > minidump on and provide you the info that was missing in textdump. > > > > This only works for easily reproducible bugs, and in that case they can turn > > on dumps later without a need for it to be automatic at all. > > And I'm arguing that those are very rare situations where there is a > bug, which is hard to reproduce and where textdump won't be of any help. Actually, this can be quite common. A stack trace alone can get you started, but the ability to check the value and state of local variables at various frames on the stack can be key to figuring out many panics. I also tended to prefer DDB several years ago, but while working at a large FreeBSD consumer with lots of machines, I found that many panics are not, in fact, very reproducible. Even for ones that are, the machine that caused the issue may not be available for testing (it's a production machine after all), so one has to make the most of post-mortem analysis and not rely on repeatedly panic'ing a machine to debug issues. In this case, kgdb is far, far more useful than ddb. None of us are smart enough to figure out all the things that ddb should possibly dump in a textdump to handle every possible panic, but with kgdb you can query new data after initial investigation of the problem. -- John Baldwin