From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43626) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQIkm-0001ft-Ua for qemu-devel@nongnu.org; Wed, 19 Mar 2014 11:50:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WQIkf-0001ea-CB for qemu-devel@nongnu.org; Wed, 19 Mar 2014 11:50:04 -0400 Received: from mail-ee0-x22a.google.com ([2a00:1450:4013:c00::22a]:53612) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQIkf-0001e9-5W for qemu-devel@nongnu.org; Wed, 19 Mar 2014 11:49:57 -0400 Received: by mail-ee0-f42.google.com with SMTP id d17so6835784eek.29 for ; Wed, 19 Mar 2014 08:49:56 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <5329BCA1.3030303@redhat.com> Date: Wed, 19 Mar 2014 16:49:53 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <20140319154247.GA31501@mail.hallyn.com> In-Reply-To: <20140319154247.GA31501@mail.hallyn.com> 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: "Serge E. Hallyn" , qemu-devel@nongnu.org Il 19/03/2014 16:42, Serge E. Hallyn ha scritto: > Hi, > > at https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1291321 > it was found that migrating running vms from a machine with > qemu-kvm to one with qemu, migration fails due to some mismatches. > The first one we usually hit is > > Length mismatch: vga.vram: 1000000 in != 800000 > > while the second one is network card (and I have not gone beyond > that). This is just a different default. Make sure you specify the right model on the command line. > The vga one can be handled on the command line by > specifying the -global cirrus-vga.vrammem_mb=8. However that > doesn't help with a libvirt migration. You can patch Ubuntu's QEMU to detect old machine types (pc-1.2 and earlier) and give cirrus-vga 16MB memory by default. Migration only works with versioned machine types (or between same-version QEMU), so it's okay to only do it there. > I guess this happens at ram_load() unfortunately - is there any > good way that this could be detected at incoming migration time > and the virtual hardware modified as needed for migration to > continue? It cannot, but the destination can be patched to operate correctly for the old machine types, on the assumption that migration from the old machine types is always from Ubuntu's qemu-kvm. Paolo