Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754469Ab2FMPh7 (ORCPT ); Wed, 13 Jun 2012 11:37:59 -0400 Received: from casper.infradead.org ([85.118.1.10]:35049 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751802Ab2FMPh6 convert rfc822-to-8bit (ORCPT ); Wed, 13 Jun 2012 11:37:58 -0400 Message-ID: <1339601872.8980.52.camel@twins> Subject: Re: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge From: Peter Zijlstra To: "H. Peter Anvin" Cc: Borislav Petkov , Stephane Eranian , linux-kernel@vger.kernel.org, andi@firstfloor.org, mingo@elte.hu, ming.m.lin@intel.com, "Yu, Fenghua" Date: Wed, 13 Jun 2012 17:37:52 +0200 In-Reply-To: <4FD89D09.6010800@zytor.com> References: <20120607071531.GA4849@quad> <4FD78BE6.4060207@zytor.com> <20120612190720.GA11137@aftab.osrc.amd.com> <1339529614.31548.104.camel@twins> <20120612194900.GC11137@aftab.osrc.amd.com> <4FD7A687.3040500@zytor.com> <20120612203730.GE11137@aftab.osrc.amd.com> <4FD7A99F.8030007@zytor.com> <20120612205609.GF11137@aftab.osrc.amd.com> <4FD7AD6F.6010008@zytor.com> <1339576681.31548.116.camel@twins> <4FD89D09.6010800@zytor.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1093 Lines: 24 On Wed, 2012-06-13 at 07:00 -0700, H. Peter Anvin wrote: > On 06/13/2012 01:38 AM, Peter Zijlstra wrote: > > On Tue, 2012-06-12 at 13:58 -0700, H. Peter Anvin wrote: > >> even things like Nehalem + Westmere in the same system > > > > Uhm,.. how well do you expect Linux to run on a franken-system like > > that? I'm pretty sure perf will malfunction in such a setup. > > > > perf might, but I have seen such frankensystems in the field and they > work (although I haven't seen that particular combo, I have to admit.) Thing is, if we boot on the wsm, perf could fault the system with nonexistent MSR accesses, if we boot on the nhm worst is wrong numbers I think. I'm not really inclined to 'fix' this.. the best I'm willing to accept is a patch that would detect this situation and simply disable all hardware perf support for the platform. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/