Re: Using loadvm with snapshot

[Kevin Wolf]

Am 17.08.2021 um 20:48 hat Peter Maydell geschrieben:
> On Tue, 17 Aug 2021 at 17:27, Dr. David Alan Gilbert
> <dgilbert@redhat.com> wrote:
> >
> > * Gabriel Southern (gsouther@qti.qualcomm.com) wrote:
> > > Hi,
> > >
> > > Are there plans to support using -loadvm with -snapshot?
> > >
> > > I saw some past discussion on mailing list including bug that was closed 
> > > earlier this year but no recent activity:
> > >
> > > https://lore.kernel.org/qemu-devel/162424905685.11837.7303570061857383641.malone@loganberry.canonical.com/
> > >
> > > Testing with latest qemu it looks like -loadvm still does not work when 
> > > combined with -snapshot.
> > >
> > > I'm curious how complex it would be to implement this feature and if it 
> > > may show up on QEMU roadmap in the future. Or if there is alterative 
> > > command that can be used to save the state of a running VM and then use 
> > > the same qcow to run multiple QEMU instances loading this VM state 
> > > running in snapshot mode.
> 
> Do you know why -loadvm and -snapshot don't work together?
> It doesn't on the face of it seem like they would be incompatible...

Probably because -snapshot first adds a temporary qcow2 overlay to the
image, and then -loadvm fails because the newly created temporary
overlay doesn't contain the requested snapshot.

Internal and external snapshots don't really mix well.

Kevin