From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jes Sorensen Subject: Re: [PATCH] Remove MSR_P6_{EVNTSEL0,PERFCTR0} from printk warning list. Date: Thu, 01 Jul 2010 16:41:14 +0200 Message-ID: <4C2CA90A.6070201@redhat.com> References: <1277908040-15087-1-git-send-email-Jes.Sorensen@redhat.com> <4C2CA84A.4090506@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:32072 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756482Ab0GAOlR (ORCPT ); Thu, 1 Jul 2010 10:41:17 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o61EfHHF016048 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 1 Jul 2010 10:41:17 -0400 In-Reply-To: <4C2CA84A.4090506@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/01/10 16:38, Avi Kivity wrote: > On 06/30/2010 05:27 PM, Jes.Sorensen@redhat.com wrote: >> From: Jes Sorensen >> >> MSR_P6_EVNTSEL0 and MSR_P6_PERFCTR0 are used to probe for the P6 PMU >> for older family 6 CPUs, which is also the default in QEMU. Ie. per >> default we get the noise of these warnings in dmesg, confusing users >> for no reason. > > For the reason, see the comment above. The guest may be trying to do > something with the counters and expect them to work. Without the > warning we'd have no idea we are knowningly misemulating something. Saw it, which is why I only suggest we remove EVNTSEL0 and PERFCTR0 but not the others. If the guest is expecting normal operation it is likely to use more than just the first. People are reporting these triggering in dmesg for both Linux and Windows guests btw. We could put them so the two in question only trigger with a debug flag or something like that? Cheers, Jes