From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55153) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XEKt2-0001Ib-OO for qemu-devel@nongnu.org; Mon, 04 Aug 2014 12:13:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XEKsu-0003kU-K0 for qemu-devel@nongnu.org; Mon, 04 Aug 2014 12:13:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57534) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XEKsu-0003kK-C0 for qemu-devel@nongnu.org; Mon, 04 Aug 2014 12:13:16 -0400 Date: Mon, 4 Aug 2014 18:13:24 +0200 From: "Michael S. Tsirkin" Message-ID: <20140804161324.GA22228@redhat.com> References: <1406054580-16763-1-git-send-email-alex@alex.org.uk> <7DADE58E-0CA0-4B97-9567-AAF5ECBC47AA@alex.org.uk> <20140729041630.GN464@ubuntumail> <82F2A47F-F096-458C-B511-26116BE78DFA@alex.org.uk> <20140804133428.GB17436@redhat.com> <20140804150831.GI9893@ubuntumail> <20140804152650.GB18760@redhat.com> <20140804153847.GE12438@ubuntumail> <387254CE-58BB-41B5-90F6-2D54112B4695@alex.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <387254CE-58BB-41B5-90F6-2D54112B4695@alex.org.uk> Subject: Re: [Qemu-devel] [PATCH] [RFC] Add machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Bligh Cc: Ryan Harper , Serge Hallyn , "quintela@redhat.com" , Libvirt , Serge Hallyn , "qemu-devel@nongnu.org" , Alexander Graf , Cole Robinson , Amit Shah , Paolo Bonzini , Bruce Rogers , Andreas =?iso-8859-1?Q?F=E4rber?= On Mon, Aug 04, 2014 at 04:47:11PM +0100, Alex Bligh wrote: > > On 4 Aug 2014, at 16:38, Serge Hallyn wrote: > > >> > >> If you really want it to be called pc-1.0, you > >> can make it a machine property instead. > >> E.g. qemu-kvm-compatibility. > >> Teach management to set it if remote is qemu-kvm: > >> -machine pc-1.0,qemu-kvm-compatibility=on > > > > That sounds nice - Alex, what do you think? > > Not having used the machine property stuff before, > or played with libvirt much, I'm not sure how this > helps libvirt. > > I thought the issue here was that migrating from > 1.0-qemu-kvm to 2.x OR 1.0-qemu-git to 2.x, libvirt > is going to to supply the same command line. > As > libvirt doesn't know what the sender is (and > it's not possible to detect this automatically - > at least not without a far more intrusive patch), Yes, this is up to higher level user. At libvirt xml level, you would just specify something like "legacy qemu-kvm compatibility" in the xml. > one has to make a choice at build time as to what > 'pc-1.0' represents. There's no choice really. Downstreams must make sure their machine types are distinct from upstream ones. qemu-kvm as a downstream violated this rule but I don't think this means upstream should violate it. > This is what patch #2 does. > I fully agree it is not pretty. The problem is not prettyness. The problem is, it creates a situation where two instances of qemu have different ideas about what a specific machine type is. > So I am not sure why > -machine pc-1.0,qemu-kvm-compatibility=on > is any easier for libvirt than > -machine pc-1.0-qemu-kvm > > IE what does using a machine property rather than > a machine type buy us? Seems to be easier to understand that it maps to pc-1.0 on the other side. > -- > Alex Bligh > > >