Re: [Qemu-devel] [RFC PATCH 3/4] qmp: Add "snapshot=" option to nbd-server-add

[Fam Zheng]

On Thu, 08/22 11:22, Paolo Bonzini wrote:
> Il 22/08/2013 10:53, Fam Zheng ha scritto:
> >> > This is handy but only works if the QEMU process has permission to
> >> > create temporary files.
> >> > 
> > Yes, this is a shortcut, it has this limitation, but the good side is
> > it's easy to get and no other dependency.
> > 
> > To avoid creating file, we'll need blockdev-add to override backing_hd,
> > and blockdev-backup to use an existing BDS as target, then we simply use
> > current nbd-server-add to export it.
> > 
> > This series is still RFC, with above said, we still need to decide which
> > is the way we (QEMU and libvirt) want for 1.7.  any thoughts?
> 
> I think this was the initial design, but Kevin already said he didn't
> like the idea.
> 
> (Also, if you do this you have to add nbd-server-add to qmp-transaction,
> to atomically start fleecing of multiple devices).
> 
Kevin,

The downside of this is unresolvable (create file in QEMU), so I am
giving up this and back to blockdev-add & blockdev-backup interface.

So I guess I'm depending on your blockdev-add command patches, do you
have a solution for overriding backing_hd there yet? If yes, do you have
a working branch that I can rebase my blockdev-backup onto?

Thanks.
Fam