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@xxxxxxxxxxxxx
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/
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