From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762059Ab2FHKAc (ORCPT ); Fri, 8 Jun 2012 06:00:32 -0400 Received: from merlin.infradead.org ([205.233.59.134]:47717 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750991Ab2FHKAb convert rfc822-to-8bit (ORCPT ); Fri, 8 Jun 2012 06:00:31 -0400 Message-ID: <1339149613.23343.52.camel@twins> Subject: Re: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge From: Peter Zijlstra To: Ingo Molnar Cc: Stephane Eranian , linux-kernel@vger.kernel.org, andi@firstfloor.org, mingo@elte.hu, ming.m.lin@intel.com Date: Fri, 08 Jun 2012 12:00:13 +0200 In-Reply-To: <20120608093513.GA22520@gmail.com> References: <20120607071531.GA4849@quad> <1339064319.23343.13.camel@twins> <1339065932.23343.18.camel@twins> <1339067757.23343.21.camel@twins> <20120608093513.GA22520@gmail.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 On Fri, 2012-06-08 at 11:35 +0200, Ingo Molnar wrote: > * Peter Zijlstra wrote: > > > On Thu, 2012-06-07 at 12:48 +0200, Stephane Eranian wrote: > > > >> The warning could also be done on boot. But the check has to be done > > > >> when the event is created. > > > > > > > > Is this because of the ucode loader not having done its thing yet etc..? > > > > Ah, its because you can update ucode at runtime of course. > > > > A quick look at the ucode loader doesn't show it having a > > notifier either, so then yeah we need to check on every event > > creation :/ > > > > Or we could put a hook in the ucode loader. > > I'd really suggest the latter - I doubt this will be our only > ucode dependent quirk, going forward ... Yeah, am in the middle of writing that..