From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49415) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQMOp-0007Hy-Jq for qemu-devel@nongnu.org; Wed, 19 Mar 2014 15:43:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WQMOk-0003e5-2E for qemu-devel@nongnu.org; Wed, 19 Mar 2014 15:43:39 -0400 Received: from mail-ee0-x22f.google.com ([2a00:1450:4013:c00::22f]:41093) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQMOj-0003dn-Ps for qemu-devel@nongnu.org; Wed, 19 Mar 2014 15:43:33 -0400 Received: by mail-ee0-f47.google.com with SMTP id b15so6965970eek.20 for ; Wed, 19 Mar 2014 12:43:32 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <5329F35F.1040203@redhat.com> Date: Wed, 19 Mar 2014 20:43:27 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <20140319154247.GA31501@mail.hallyn.com> <5329BCA1.3030303@redhat.com> <20140319155216.GA31857@mail.hallyn.com> <20140319161631.GA32205@mail.hallyn.com> <20140319170855.GA10575@work-vm> <20140319173741.GA621@mail.hallyn.com> <20140319174629.GB10575@work-vm> In-Reply-To: <20140319174629.GB10575@work-vm> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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" , "Serge E. Hallyn" Cc: qemu-devel@nongnu.org Il 19/03/2014 18:46, Dr. David Alan Gilbert ha scritto: > * Serge E. Hallyn (serge@hallyn.com) wrote: >> 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? > > Right - but they might have kept it as -M pc-1.0 on purpose, so that they > can migrate it back to another machine with an older qemu. No, this is not supported upstream. Upstream only supports forward migration. >>> 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... This is correct. Paolo