From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NSVt0-0005kE-S4 for qemu-devel@nongnu.org; Wed, 06 Jan 2010 08:25:18 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NSVsw-0005gt-7C for qemu-devel@nongnu.org; Wed, 06 Jan 2010 08:25:18 -0500 Received: from [199.232.76.173] (port=45060 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NSVsv-0005gm-T8 for qemu-devel@nongnu.org; Wed, 06 Jan 2010 08:25:13 -0500 Received: from mail-yw0-f176.google.com ([209.85.211.176]:47776) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NSVsv-0001Jc-K8 for qemu-devel@nongnu.org; Wed, 06 Jan 2010 08:25:13 -0500 Received: by ywh6 with SMTP id 6so17399841ywh.4 for ; Wed, 06 Jan 2010 05:25:13 -0800 (PST) Message-ID: <4B448F36.8030605@codemonkey.ws> Date: Wed, 06 Jan 2010 07:25:10 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] cpuid problem in upstream qemu with kvm References: <4B2DF334.6030208@redhat.com> <20091220155101.GB31257@redhat.com> <4B2E49E5.6050709@redhat.com> <20091220165612.GC31257@redhat.com> <20091220171822.GD31257@redhat.com> <20091220172341.GB21163@redhat.com> <2162E312-0110-42E1-A391-D75A6F013554@suse.de> <20091220173702.GC21163@redhat.com> <4B2E660F.1050703@codemonkey.ws> <20091221074355.GU4490@redhat.com> <4B2F31B1.6040403@redhat.com> <4B30EFDF.4060202@codemonkey.ws> <4B31F1BA.10005@redhat.com> <4B43D4E2.9050102@codemonkey.ws> <4B4402B1.1030605@redhat.com> In-Reply-To: <4B4402B1.1030605@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Gleb Natapov , "Michael S. Tsirkin" , John Cooper , dlaor@redhat.com, qemu-devel@nongnu.org, Alexander Graf On 01/05/2010 09:25 PM, Avi Kivity wrote: >> Typically, there is at least a little sanity naming for these cases. >> For instance, any Xeon W35xx should have the same features. A Xeon >> W55xx may be different. >> >> It's not going to be easy to include every possible model. It's a >> hard problem for management tools too. The thing is, I imagine most >> management tools are going to cat /proc/cpuinfo to get what the >> processor is and that's going to be a Xeon YYXXXX type name so I >> really believe that's the thing that makes sense to expose in QEMU. >> >> Maybe we could name models like IntelXeonW35xx. >> > > While a W3501 should be similar to a W3599, we don't know if it > actually will be. You are no longer on a Fully Correct path and > instead you are wandering in Marketing Land. > > Note that the processor type is just part of what determines which > features are exposed to the guest. Qemu version, kvm version, host > kernel version, and even kernel command-line parameters all play a > part, so to really determine migratability the management tool should > talk to qemu, not /proc/cpuinfo. So if I understand correctly, you're advocating to drop the idea of common model names, and provide a mechanism for a management tool to query which cpu features are supported both by the processor, but also filtered by qemu, kvm, etc? I think that's workable but I think there may be some subtle issues especially across qemu versions. Can you give an example of what you would expect the output to be? >> Clever use of the preprocessor will make this effort much, much saner. > > I cringe whenever I read something like this. :-) Regards, Anthony Liguori