From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: tainted Linux kernel in default SMP QEMU/KVM guests Date: Tue, 23 Mar 2010 12:45:18 +0200 Message-ID: <4BA89BBE.5040100@redhat.com> References: <4BA36B06.5060002@amd.com> <4BA374F9.9040008@redhat.com> <4BA37824.6000504@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Paolo Bonzini , Andre Przywara , QEMU devel , KVM list To: Anthony Liguori Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55007 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751627Ab0CWKpY (ORCPT ); Tue, 23 Mar 2010 06:45:24 -0400 In-Reply-To: <4BA37824.6000504@codemonkey.ws> Sender: kvm-owner@vger.kernel.org List-ID: On 03/19/2010 03:12 PM, Anthony Liguori wrote: > On 03/19/2010 07:58 AM, Paolo Bonzini wrote: >> >>> 1) Change the default CPUID bits from 6/2/3 to 6/6/1, this passes the >>> Linux kernel check. But I am not sure if that would introduce >>> regressions, since some OSes apply quirks if they detect certain models >>> (like we had with the sysenter issue in the past) >>> >>> 2) Only change the CPUID bits to 6/6/1 if we use SMP. Still has the >>> above drawback, but would be limited to SMP guests only. >>> >>> 3) Set kvm64/kvm32 as the default CPU model if KVM is enabled. This >>> would limit the report and taint to TCG, where SMP is rarely used. >>> Additionally less people (if any) use it for production systems. >>> >>> 4) Make the Linux' kernel quirk dependent on the missing hypervisor >>> bit. >>> I don't think this will be accepted easily upstream (and I don't >>> want to >>> support Ingo's recent ideas ;-), also this would not fix older kernels. >>> >>> I can easily provide patches for all solutions, but I'd like to get >>> advice from people on which one to pursue. >> >> Doing (3) seems the most sensible thing to do, and it does not >> prevent doing (1) later on for TCG only. > > Let's switch to -cpu host for kvm. Except for -M old. This has the nice advantage of exposing new features as they are rolled out. -- error compiling committee.c: too many arguments to function