From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760505AbZATPXy (ORCPT ); Tue, 20 Jan 2009 10:23:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756876AbZATPXp (ORCPT ); Tue, 20 Jan 2009 10:23:45 -0500 Received: from mx2.redhat.com ([66.187.237.31]:59376 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756383AbZATPXo (ORCPT ); Tue, 20 Jan 2009 10:23:44 -0500 Date: Tue, 20 Jan 2009 10:22:56 -0500 From: Vivek Goyal To: Neil Horman Cc: linux-kernel@vger.kernel.org, hbabu@us.ibm.com, kexec@lists.infradead.org, horms@verge.net.au, akpm@linux-foundation.org Subject: Re: [PATCH]: add dmesg log symbols to /proc/vmcoreinfo lists Message-ID: <20090120152255.GB5125@redhat.com> References: <20090119212127.GA13157@hmsreliant.think-freely.org> <20090120141551.GA5125@redhat.com> <20090120150958.GB18207@hmsreliant.think-freely.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090120150958.GB18207@hmsreliant.think-freely.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 20, 2009 at 10:09:58AM -0500, Neil Horman wrote: > On Tue, Jan 20, 2009 at 09:15:51AM -0500, Vivek Goyal wrote: > > On Mon, Jan 19, 2009 at 04:21:27PM -0500, Neil Horman wrote: > > > Hey all- > > > It would be nice to be able to extract the dmesg log from a vmcore file > > > without needing to keep the debug symbols for the running kernel handy all the > > > time. We have a facility to do this in /proc/vmcore. This patch adds the > > > log_buf and log_end symbols to the vmcoreinfo area so that tools (like > > > makedumpfile) can easily extract the dmesg logs from a vmcore image. > > > > > > > It would be nice to get dmesg log if debug symbols are not around. Can't > > we use System.map for getting symbol addresses? vmcoreinfo had started > > small and seems to be growing now. I am thinking down the line will making > > use of System.map for such cases make sense? > > > > System.map only include exported and public symbols. log_buf and log_end are > static, and not reported in the System.map. Its a nice idea, but not > comprehensive for everything in the kernel. > > > > > > > Will it be an issue if we make log_buf and log_end non static and directly > > access these in kexec.c? > > > I had considered that, but was a bit hesitant to do so, since it exposes the > internal implementation of the dmesg buffer. In the event someone disables > CONFIG_PRINTK, thats just more code we need to ifdef. With this implementation > we just stub out the log_buf_setup function, and let that be that. It seems > more consice to me this way. > Makes sense to me. Acked-by: Vivek Goyal Thanks Vivek