Quoting Serge E. Hallyn (se...@hallyn.com): > Quoting Paolo Bonzini (pbonz...@redhat.com): > > 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 > > Ah, thank you, that assumption should be safe and sounds like a > great idea.
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. -serge
