From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934941Ab1JEQQc (ORCPT ); Wed, 5 Oct 2011 12:16:32 -0400 Received: from mail.skyhub.de ([78.46.96.112]:51903 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934476Ab1JEQQa (ORCPT ); Wed, 5 Oct 2011 12:16:30 -0400 Date: Wed, 5 Oct 2011 18:16:26 +0200 From: Borislav Petkov To: Valdis.Kletnieks@vt.edu Cc: Vivek Goyal , "K.Prasad" , Borislav Petkov , "Eric W. Biederman" , linux-kernel@vger.kernel.org, crash-utility@redhat.com, kexec@lists.infradead.org, Andi Kleen , "Luck, Tony" , anderson@redhat.com, tachibana@mxm.nes.nec.co.jp, oomichi@mxs.nes.nec.co.jp Subject: Re: [Patch 1/4][kernel][slimdump] Add new elf-note of type NT_NOCOREDUMP to capture slimdump Message-ID: <20111005161626.GB18592@gere.osrc.amd.com> References: <20111003070735.GJ2223@in.ibm.com> <20111003073203.GA22694@in.ibm.com> <20111003120336.GK2223@in.ibm.com> <20111004063440.GB5723@liondog.tnic> <20111005070728.GA2235@in.ibm.com> <20111005073111.GA13478@liondog.tnic> <20111005094727.GB7485@in.ibm.com> <20111005155217.GE30146@redhat.com> <10327.1317830438@turing-police.cc.vt.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <10327.1317830438@turing-police.cc.vt.edu> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 05, 2011 at 12:00:38PM -0400, Valdis.Kletnieks@vt.edu wrote: > On Wed, 05 Oct 2011 11:52:17 EDT, Vivek Goyal said: > > > I am assuming that basic MCE error messages are available in kernel log. > > They're not in the kernel log if it's an MCE that causes the kernel to declare > a panic. There's some MCE's that you can retry the operation and continue, and > some that you can get away with poisoning a page, killing the process, and rest > of the system is OK. But some you really need to roll over and die because you > can't guarantee kernel integrity anymore. > > And at that point, those messages are never gonna make it to syslogd and onto > disk. AFAICT, and for the sake of getting the MCE info, arguably one could look for log_buf in the vmcore of the old kernel and try to find the last lines in the kernel log ringbuffer. They should be the MCE error information from the do_machine_check MCE handler. This all assuming of course we've managed to dump vmcore successfully by sidestepping the landmines :-). -- Regards/Gruss, Boris.