From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54512) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bFT81-00076v-8g for qemu-devel@nongnu.org; Tue, 21 Jun 2016 17:22:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bFT7x-0004VL-1G for qemu-devel@nongnu.org; Tue, 21 Jun 2016 17:22:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58105) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bFT7w-0004VH-S2 for qemu-devel@nongnu.org; Tue, 21 Jun 2016 17:22:32 -0400 Date: Tue, 21 Jun 2016 18:22:30 -0300 From: Eduardo Habkost Message-ID: <20160621212230.GL2048@thinpad.lan.raisama.net> References: <1466514153-85777-1-git-send-email-dahi@linux.vnet.ibm.com> <20160621164431.GI2048@thinpad.lan.raisama.net> <20160621190144.174c93cd@thinkpad-w530> <20160621203309.GK2048@thinpad.lan.raisama.net> <20160621210949.GH4783@orkuz.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160621210949.GH4783@orkuz.home> Subject: Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand , qemu-devel@nongnu.org, imammedo@redhat.com, cornelia.huck@de.ibm.com, borntraeger@de.ibm.com, fiuczy@linux.vnet.ibm.com, mimu@linux.vnet.ibm.com, libvir-list@redhat.com On Tue, Jun 21, 2016 at 11:09:49PM +0200, Jiri Denemark wrote: [...] > > 1) "query-cpu-model-expansion model=host" vs "query-host-cpu": > > > > I still don't think we want to set in stone that "the result the > > guest sees when using -cpu host" is always the same as "what the > > host supports running". > > > > For example: let's assume a given architecture have two features > > (A and B) that are both supported by the host but can never be > > enabled together. For actual "-cpu host" usage, QEMU would have > > to choose between enabling A and B. For querying host > > capabilities, we still want to let management software know that > > either A or B are supported. > > What libvirt is really interested in is the guest CPU which would be > used with -cpu host. This is actually what I thought query-host-cpu was > all about. Perhaps because there's no difference for x86. In that case, I think it makes sense to just extend query-cpu-definitions or use "query-cpu-model-expansion model=host" instead of a query-host-cpu command. Probably query-cpu-model-expansion is better than just extending query-cpu-definitions, because it would allow the expansion of extra CPU options, like "host,migratable=off". -- Eduardo