From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753866AbYGVNqZ (ORCPT ); Tue, 22 Jul 2008 09:46:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750975AbYGVNqQ (ORCPT ); Tue, 22 Jul 2008 09:46:16 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:49154 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752073AbYGVNqP (ORCPT ); Tue, 22 Jul 2008 09:46:15 -0400 Date: Tue, 22 Jul 2008 15:46:01 +0200 From: Ingo Molnar To: "H. Peter Anvin" Cc: "Luis R. Rodriguez" , linux kernel , "H. Peter Anvin" , Ivan Seskar , jfm3 , Sujith Subject: Re: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot Message-ID: <20080722134601.GA21977@elte.hu> References: <43e72e890807210614y58065d75j5b2fb3c5ebe6180a@mail.gmail.com> <48848DDF.6010903@zytor.com> <43e72e890807210701w6d7f5638w5fdbea76a1cf1c0b@mail.gmail.com> <48851AC2.8030007@zytor.com> <20080722131408.GA12418@elte.hu> <4885DF9D.2090804@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4885DF9D.2090804@zytor.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean 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=3.2.3 -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 * H. Peter Anvin wrote: > Ingo Molnar wrote: >>> >>> Not a bug. >> >> it would still be nice to get a nice printk and panic during bootup >> instead of some obscure crash, hm? >> > > Yes. The fundamental problem is that Centaur has a set of CPUs which > report family == 6 but don't have the long NOP instructions. We would > need an exact CPUID criterion for these CPUs in order to be able to > report it as an error. An alternative would be to attempt trapping in > the real-mode code (#UD is one of the *very* few CPU exceptions which > can be reliably captured in real mode on a BIOS system), but doing so > would probably mean breaking Loadlin at the very least. > > We can't "printk and panic" because we never get that far in the > kernel proper, for obvious reasons: the code is quite littered with > these buggers. hm. How about to default to a safe NOP all the way up to where we can fix up alternatives and install a different NOP. (which we could also test first via intentionally jumping on it and catching any exception via a special exception handler) Ingo