From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47193) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQKR2-0003GE-4r for qemu-devel@nongnu.org; Wed, 19 Mar 2014 13:37:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WQKQx-0000gw-8O for qemu-devel@nongnu.org; Wed, 19 Mar 2014 13:37:48 -0400 Received: from static.92.5.9.176.clients.your-server.de ([176.9.5.92]:39460 helo=hallynmail2) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQKQx-0000gm-2N for qemu-devel@nongnu.org; Wed, 19 Mar 2014 13:37:43 -0400 Date: Wed, 19 Mar 2014 18:37:41 +0100 From: "Serge E. Hallyn" Message-ID: <20140319173741.GA621@mail.hallyn.com> References: <20140319154247.GA31501@mail.hallyn.com> <5329BCA1.3030303@redhat.com> <20140319155216.GA31857@mail.hallyn.com> <20140319161631.GA32205@mail.hallyn.com> <20140319170855.GA10575@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140319170855.GA10575@work-vm> Subject: Re: [Qemu-devel] migrating instances from qemu-kvm to qemu List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: Paolo Bonzini , qemu-devel@nongnu.org, "Serge E. Hallyn" Quoting Dr. David Alan Gilbert (dgilbert@redhat.com): > * Serge E. Hallyn (serge@hallyn.com) wrote: > > > Although, some people are using newer qemu with '-M pc-1.0'. So we'd be > > stopping thing from migrating to support the people coming from qemu-kvm. > > Hmm. > > What sometimes happens is that you create a VM (lets say with virt-manager) > on an old installation, and it has the XML file for that VM which I think > includes the machine type. You upgrade your host or copy your VMs over > and so you still use the old machine definition, and hence still have the > -M pc-1.0 Right, but so long as it is a shutdown vm image, it shouldn't matter to this case whether qemu 1.7 uses the old qemu-kvm cirrus vga ram size, or the qemu ram size, right? > Some people have snapshots rather than just disk images taken with particular > versions and they expect those to be reloadable into newer versions. Disk snapshots should be fine right? Live snapshots no, but then I didn't they were actually very well supported anyway. In any case, they point would remain that if x% of people have snapshots from qemu-kvm, and the rest have snapshots created using qemu but older machine types, then whether or not we change the values, either way the other x% or 100-x % will not be able to restore... So still it seems the only sure way to handle this would be for qemu to say "old vram size != new vram size; so let me resize the vram". -serge