From: Jamie Lokier Subject: Re: [Qemu-devel] [PATCH] Add definitions for current cpu models.. Date: Tue, 19 Jan 2010 22:15:48 +0000 Message-ID: <20100119221548.GC11920@shareable.org> References: <4B549016.6090501@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: KVM list , qemu-devel@nongnu.org, "Przywara, Andre" To: john cooper Return-path: Received: from mail2.shareable.org ([80.68.89.115]:39689 "EHLO mail2.shareable.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754281Ab0ASWPt (ORCPT ); Tue, 19 Jan 2010 17:15:49 -0500 Content-Disposition: inline In-Reply-To: <4B549016.6090501@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: 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. 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. -- Jamie