Re: [Qemu-devel] [libvirt] [BUG] Re: [2/6] loadvm: improve tests before bdrv_snapshot_goto()

[Eric Blake]

On 04/14/2011 03:29 AM, Kevin Wolf wrote:
> Am 14.04.2011 11:10, schrieb Philipp Hahn:

Reviving an old thread...

> > Hello,
> >
> > Am Dienstag 03 August 2010 06:44:26 schrieb Kevin Wolf:
> > > From: Miguel Di Ciurcio Filho<address@hidden>
> > >
> > > This patch improves the resilience of the load_vmstate() function, doing
> > > further and better ordered tests.
> >
> > This patch broke restoring not-running VMs using libvirt-0.8.7 with qemu-0.14:
> > When the domain is not running while taking a snpshot, the sn.vm_state_size
> > == 0:
> >
> > [...]
> >
> > Previously the qcow2 image was still reverted to the old state, so on the next
> > start of the domain the qcow2 image would be in the state of the snapshot
> >
> > [...]
> >
> > Now the qcow2 image is not reverted and when the domain is started, it is NOT
> > in the state of the snapshot.
> >
> > I can't decide if this regression is an Qemu bug or libvirt should be adapted
> > to this new behavior.
>
> Ouch. I wouldn't have expected that libvirt relies on this qemu bug.
> When libvirt doesn't use the VM state but boots a fresh VM, it should
> call qemu-img snapshot -a for the disks rather than using the loadvm
> monitor command.

Libvirt should be using 'qemu-img snapshot -a' before reverting to a 
snapshot made via 'qemu-img snapshot -c'; I'm writing the patch now.

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org