From owner-freebsd-questions@FreeBSD.ORG Mon Feb 25 13:37:03 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 8728E16A409 for ; Mon, 25 Feb 2008 13:37:03 +0000 (UTC) (envelope-from fbsd.questions@rachie.is-a-geek.net) Received: from snoogles.rachie.is-a-geek.net (rachie.is-a-geek.net [66.230.99.27]) by mx1.freebsd.org (Postfix) with ESMTP id 5601013C459 for ; Mon, 25 Feb 2008 13:37:03 +0000 (UTC) (envelope-from fbsd.questions@rachie.is-a-geek.net) Received: from localhost (localhost [127.0.0.1]) by snoogles.rachie.is-a-geek.net (Postfix) with ESMTP id CAA771CC8B; Mon, 25 Feb 2008 04:37:01 -0900 (AKST) From: Mel To: freebsd-questions@freebsd.org Date: Mon, 25 Feb 2008 14:36:31 +0100 User-Agent: KMail/1.9.7 References: <6C2C79E72C305246B504CBA17B5500C9036415A4@mtlexch01.mtl.com> In-Reply-To: <6C2C79E72C305246B504CBA17B5500C9036415A4@mtlexch01.mtl.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200802251436.32206.fbsd.questions@rachie.is-a-geek.net> Cc: Yehonatan Yossef Subject: Re: Capturing dmesg upon system crash on 6.3 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: Mon, 25 Feb 2008 13:37:03 -0000 On Monday 25 February 2008 13:32:01 Yehonatan Yossef wrote: > > > I'm facing a system reboot upon loading of the driver, and > > > > I could use > > > > > a tool for capturing dmesg upon system crash (such as netconsole on > > > Linux). > > > > Your kernel isn't setup for driver development: > > http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-ha > > ndbook/kerneldebug.html > > http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kern > > elconfig.html > > > > Basically, your system is rebooting cause the kernel panics > > and you're not setup for crash dumps, or anything that could > > help you diagnose the panic. > > -- > > Mel > > I've setup the dumpdev/dumpdir and I get a vmcore image upon a crash. > > I don't really understand how to use kgdb in order to read it but more > than that - I don't need that much of data. I only want the dmesg report > at the moment, see at what point my driver went crazy. Is it possible? Uhm, no. Fundamental logic flaw: when a kernel is stopped, you can't issue userland commands. All you have when you use ddb, is the contents of the registers, ram and backtrace. You really want ddb in the kernel: when a kernel panics, it'll drop to ddb and you can examine registers and do a backtrace, instead of dumping core and rebooting. It should point exactly to where your driver went crazy. -- Mel