From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] Remove MSR_P6_{EVNTSEL0,PERFCTR0} from printk warning list. Date: Thu, 01 Jul 2010 17:44:22 +0300 Message-ID: <4C2CA9C6.60605@redhat.com> References: <1277908040-15087-1-git-send-email-Jes.Sorensen@redhat.com> <4C2CA84A.4090506@redhat.com> <4C2CA90A.6070201@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Jes Sorensen Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47372 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751718Ab0GAOoY (ORCPT ); Thu, 1 Jul 2010 10:44:24 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o61EiO1n028531 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 1 Jul 2010 10:44:24 -0400 Received: from cleopatra.tlv.redhat.com (cleopatra.tlv.redhat.com [10.35.255.11]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o61EiMwk016136 for ; Thu, 1 Jul 2010 10:44:23 -0400 In-Reply-To: <4C2CA90A.6070201@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/01/2010 05:41 PM, Jes Sorensen wrote: > 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. > Why is that? > 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? > What values are the guests writing? Are they really expecting this thing to work? What would it take to emulate those counters? They're supposed to be relatively simple, no? -- error compiling committee.c: too many arguments to function