From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757575AbZHQJSl (ORCPT ); Mon, 17 Aug 2009 05:18:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757554AbZHQJSl (ORCPT ); Mon, 17 Aug 2009 05:18:41 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:34351 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757553AbZHQJSk (ORCPT ); Mon, 17 Aug 2009 05:18:40 -0400 Date: Mon, 17 Aug 2009 11:18:00 +0200 From: Ingo Molnar To: Hidetoshi Seto Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, ak@linux.intel.com, tglx@linutronix.de, Yinghai Lu , Huang Ying , "Rafael J. Wysocki" , linux-tip-commits@vger.kernel.org Subject: Re: [boot crash] Re: [tip:x86/mce3] x86, mce: use 64bit machine check code on 32bit Message-ID: <20090817091800.GA21269@elte.hu> References: <20090812113652.GA19632@elte.hu> <4A88E3E4.40506@jp.fujitsu.com> <20090817083544.GC15390@elte.hu> <4A891E17.1090901@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A891E17.1090901@jp.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Hidetoshi Seto wrote: > Ingo Molnar wrote: > > * Hidetoshi Seto wrote: > >> Could you try boot your laptop with mce=nobootlog? > > > > Hm, why should that make any difference? mce=nobootlog only > > influences whether we pass records into the mcelog buffer but > > does not affect whether we touch the hardware. > > Old mce codes doesn't take bootlog. I understand what you mean, and i know that we have a number of BIOS workarounds in the code - but i think some of those workarounds are wrong and they dont actually solve anything. The thing is, mce=nobootlog does _not_ keep us from touching MCE related hardware registers during bootup. It only inhibits us from doing an mce_log() call: if (!(flags & MCP_DONTLOG) && !mce_dont_log_ce) { mce_log(&m); add_taint(TAINT_MACHINE_CHECK); } but an mce_log() call itself only passes on the data we already read from hardware registers, into the MCE ring-buffer (which is a pure software construct). > One possibility is: if the BIOS doesn't clear status in banks, > new mce codes will try to log such junks. > > If the junk is totally junk but can be decoded as a valid log with > MISCV or ADDRV bit, and if the cpu try to access register which is > not implemented (e.g. IA32_MCi_MISC/ADDR), then such access might > cause a general protection exception. (ref. ASDM 3A 15.3.2.3) > > I'm just guessing... My point is that mce=nobootlog will only affect whether we call mce_log(). It does not keep us from touching all the MSRs that relate to MCEs. mce=off does that, and the box boots up fine with that specified (and as expected). Ingo