[libvirt] [PATCH] qemu: snapshot: Keep non-persistent changes alive in snapshot

[Jiri Denemark]

On Fri, Oct 27, 2017 at 18:47:51 +0530, Madhu Pavan wrote:
> On 10/27/2017 02:51 PM, Jiri Denemark wrote:
> > I think this is actually a bit more complicated. When reverting to a
> > snapshot, when reverting a snapshot we should revert both active and
> > inactive configuration for backward compatibility and also because it
> > makes sense. Imagine you made a snapshot of a running domain, played
> > with the domain configuration and then reverted the state of the domain
> > to the snapshot. Once you shutdown the domain and start it again you'd
> > get a completely different machine. Of course, you actually may want
> > such behavior. Thus we can't really guess whether a user wants to revert
> > both active and inactive configuration or just one of them. The user
> > should be able to tell us what to do (and we should revert both configs
> > if no preference is given).
> >
> > However, for this to be really useful we need to store both active and
> > inactive configurations when creating a snapshot of a running domain.
> With the current behavior that I see from snapshot-list, I understood we 
> categorize the snapshots
> as "Active (running, paused)" or "config(shutoff)" depending if the 
> snapshot was taken on an
> active or inactive domain. With my use case what I observed was that the 
> revert of active
> snapshot actually overwriting inactive domain configuration. I thought 
> only the "config" snapshot
> alone can overwrite the inactive domain configuration. Hence this patch. 
> Are you suggesting we
> should have both active and inactive domain configurations to be saved 
> for an active guest and
> restore (both by default) OR (provide options to select)?

Yes, exactly.

Jirka