From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758552Ab1EZXoI (ORCPT ); Thu, 26 May 2011 19:44:08 -0400 Received: from kirsty.vergenet.net ([202.4.237.240]:49187 "EHLO kirsty.vergenet.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754820Ab1EZXoH (ORCPT ); Thu, 26 May 2011 19:44:07 -0400 Date: Fri, 27 May 2011 08:44:01 +0900 From: Simon Horman To: Vivek Goyal Cc: Andi Kleen , "K.Prasad" , Linux Kernel Mailing List , "Luck, Tony" , kexec@lists.infradead.org, "Eric W. Biederman" , anderson@redhat.com Subject: Re: [RFC Patch 5/6] slimdump: Capture slimdump for fatal MCE generated crashes Message-ID: <20110526234401.GE2815@verge.net.au> References: <20110526170722.GB23266@in.ibm.com> <20110526172305.GA18295@in.ibm.com> <20110526174447.GC29496@redhat.com> <20110526180931.GF4065@one.firstfloor.org> <20110526182618.GD29496@redhat.com> <20110526185838.GG4065@one.firstfloor.org> <20110526191008.GF29496@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110526191008.GF29496@redhat.com> Organisation: Horms Solutions Ltd. 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 Thu, May 26, 2011 at 03:10:08PM -0400, Vivek Goyal wrote: > On Thu, May 26, 2011 at 08:58:38PM +0200, Andi Kleen wrote: > > > If we are just extracting and saving MCE registers from vmcore, then > > > reboot time does not increase. It increases only if user decides to > > > extract and save extra data from vmcore. > > > > Hmm I was thinking of user space usually saving the dump first > > before analyzing it. But yes it could probably do some minimal > > analysis first. > > In RHEL, now we filter out the dump by default until and unless user > decides to no filter the dump with the help of config options. > > So I think in this case we can just introduce an extra filtering > option in "makedumpfile" and ask it to save only MCE registers > if it notices that there is NT_MCE type of ELF note in vmcore. > > I can very well imaging that extracting dmesg along with MCE registers > can be useful. If nothing else, it can give us useful information about > the system configuration. > > Zeroing out all the other ELF headers in vmcore takes away the > capability to extract log buffers in case of MCE and I think > it probably is not the best idea. > FWIW, my initial thoughts are inline with Vivek's. I think that the bulk of this, if not all of it, can be done in user space. And that user space is the preferable location for such logic.