Hello, I'm using libvirt to manage my KVM instances. I created a VM with qemu-kvm-0.12, later upgraded to qemu-kvm-0.14 and took a snapshot using libvirt. As the original VM was created with qemu-kvm-0.12, libvirt stored "pc-0.12" with its XML data. Now I upgraded to qemu-kvm-1.1.2, where reverting to that snapshot fails with a the message

Unknown savevm section or instance 'kvmclock' 0 load of migration failed

I tracked that down to hw/pc_piix.c:590 where

static QEMUMachine pc_machine_v0_12 = { .name = "pc-0.12", .desc = "Standard PC", .init = pc_init_pci_no_kvmclock, is defined. If I change .init to pc_init_pci, I'm able to load the old snapshot.

I think this is because kvm-0.14 always created the kvmclock device, while that was only later changed (0ec329da) to be created "on demand" for pc-0.14s onward. So the snapshot is no longer a pure pc-0.12, but some pc-0.12+something, which qemu-kvm-1.1.2 refuses to load. Now that I know what the problem is I just want to inform others, who might experience the same problem. My workaround is a patched qemu-kvm, where I changed that .init mentioned above, since an additional enabled kvmclock does not seem to do any harm. If someone has a better fix, I'm open to suggestions. Sincerely Philipp -- Philipp Hahn Open Source Software Engineer hahn@univention.de Univention GmbH be open. fon: +49 421 22 232- 0 Mary-Somerville-Str.1 D-28359 Bremen fax: +49 421 22 232-99 http://www.univention.de/