On Wed, Jun 09, 2010 at 11:22:55AM -0500, Anthony Liguori wrote: > On 06/09/2010 10:31 AM, Daniel P. Berrange wrote: > >> However, libvirt was counting on this feature and on the snapshot > >> commands > >>to switch from the text Monitor. We have two options: > >> > >> 1. Ask them to wait one more release (not so good for us) > >> 2. Try to find a way to have those features in for 0.13 > >> > >> Daniel has commented to me that making the snapshot commands synchronous > >>for 0.13 wouldn't be that bad, what do you think? > >> > >The thought is that changing a command from synchronous to asynchronous is > >not an ABI incompatible change. An existing app simply won't know to take > >advantage of the new possibilities that async commands offer. > > > > It's not QMP that's the major issue with savevm. The major issue is > actually the way snapshots are saved in qcow2. You need to know the > size of the snapshot prior to creating the snapshot which is not > possible if you want to make snapshots live. In order to support this > functionality, we'll probably have to introduce a new snapshot format in > qcow2. > > Honestly, I would recommend not supporting snapshots in libvirt until we > did the work to make snapshots live. Snapshots can cause guests to > generate errors as it stands today and fixing that will almost certainly > result in backwards compatibility considerations. Libvirt already supports savevm in the text mode monitor, hence the desire to have it work in QMP too. > If we did put savevm in QMP today, we would need to provide an interface > that let applications detect when we eventually fix this. The problem you describe sounds like an internal qcow2 implementation detail. The savevm related commands & their parameters don't have anything that's inherantly tied to qcow2, so why would it affect QMP if qcow2 format changed internally ? Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
