From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by canuck.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1RBTM5-0001sM-6O for kexec@lists.infradead.org; Wed, 05 Oct 2011 15:25:58 +0000 Date: Wed, 5 Oct 2011 11:25:37 -0400 From: Vivek Goyal Subject: Re: [Patch 1/4][kernel][slimdump] Add new elf-note of type NT_NOCOREDUMP to capture slimdump Message-ID: <20111005152537.GB30146@redhat.com> References: <20111003070735.GJ2223@in.ibm.com> <20111003073203.GA22694@in.ibm.com> <20111004140437.GA28306@redhat.com> <20111005071844.GB2235@in.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20111005071844.GB2235@in.ibm.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: "K.Prasad" Cc: oomichi@mxs.nes.nec.co.jp, "Luck, Tony" , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, tachibana@mxm.nes.nec.co.jp, Andi Kleen , anderson@redhat.com, "Eric W. Biederman" , Borislav Petkov , crash-utility@redhat.com On Wed, Oct 05, 2011 at 12:48:44PM +0530, K.Prasad wrote: > On Tue, Oct 04, 2011 at 10:04:37AM -0400, Vivek Goyal wrote: > > On Mon, Oct 03, 2011 at 01:02:03PM +0530, K.Prasad wrote: > > > There are certain types of crashes induced by faulty hardware in which > > > capturing crashing kernel's memory (through kdump) makes no sense (or sometimes > > > dangerous). > > > > > > A case in point, is unrecoverable memory errors (resulting in fatal machine > > > check exceptions) in which reading from the faulty memory location from the > > > kexec'ed kernel will cause double fault and system reset (leaving no > > > information for the user). > > > > Prasad, > > > > I am just trying to remember what was wrong with Andi's approach of > > disable MCE while copying the dump? > > > > Hi Vivek, > The behaviour upon a read operation on an UC memory location is > undefined and so we want to avoid it (previously discussed here: > http://article.gmane.org/gmane.linux.kernel/1146799). > When we disable MCE and copy the dump, we will invariably read the faulty > memory location. And how that is worse then not capturing a dump at all? Anyway, you said that in case of MCE vmcore is of no use and we don't want to capture it. Thanks Vivek _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec