From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NXgyK-0005Fg-9k for qemu-devel@nongnu.org; Wed, 20 Jan 2010 15:16:12 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NXgyF-0005A9-KC for qemu-devel@nongnu.org; Wed, 20 Jan 2010 15:16:11 -0500 Received: from [199.232.76.173] (port=45268 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NXgyF-0005A4-AP for qemu-devel@nongnu.org; Wed, 20 Jan 2010 15:16:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:3258) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NXgyE-0002uT-Sm for qemu-devel@nongnu.org; Wed, 20 Jan 2010 15:16:07 -0500 Message-ID: <4B57638A.1060103@redhat.com> Date: Wed, 20 Jan 2010 15:11:54 -0500 From: john cooper MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] Add definitions for current cpu models.. References: <4B549016.6090501@redhat.com> <20100119221548.GC11920@shareable.org> In-Reply-To: <20100119221548.GC11920@shareable.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jamie Lokier Cc: john.cooper@redhat.com, "Przywara, Andre" , qemu-devel@nongnu.org, KVM list Jamie Lokier wrote: > john cooper wrote: >> As before a cpu feature 'check' option is added which warns when >> feature flags (either implicit in a cpu model or explicit on the >> command line) would have otherwise been quietly unavailable to a >> guest: >> >> # qemu-system-x86_64 ... -cpu Nehalem,check >> warning: host cpuid 0000_0001 lacks requested flag 'sse4.2' [0x00100000] >> warning: host cpuid 0000_0001 lacks requested flag 'popcnt' [0x00800000] > > That's a nice feature. Can we have a 'checkfail' option which refuses > to run if a requested capability isn't available? Thanks. Certainly, others have requested the same. Let's resolve the issue at hand first. > I foresee wanting to iterate over the models and pick the latest one > which a host supports - on the grounds that you have done the hard > work of ensuring it is a reasonably good performer, while "probably" > working on another host of similar capability when a new host is made > available. That's a fairly close use case to that of safe migration which was one of the primary motivations to identify the models being discussed. Although presentation and administration of such was considered the domain of management tools. -john -- john.cooper@redhat.com