[libvirt] [PATCH v5 4/5] conf: add features to snapshot disk XML

[Martin Kletzander]

On 06/19/2013 05:24 PM, Ján Tomko wrote:
> Add <features> and <compat> elements to snapshot disk XML.
> 
> <compat> is a string which for qcow2 represents the QEMU version
> it should be compatible with. Valid values are 0.10 and 1.1.
> 1.1 is implicit if the <features> element is present, otherwise
> qemu-img default is used. 0.10 can be specified to explicitly
> create older images after the qemu-img default changes.
> 
> <features> contains optional features, so far
> <lazy_refcounts/> is available.
> ---

Some code duplication from the previous patches done here, but that's
fine due to the nature of the snapshot design, I guess.

What could be changed is the fact that (as per discussion with you),
there should be check that these new things are not requested in an XML
for snapshot which doesn't support them or we can't control them
(internal or active).

I can't also decide whether we want this support in the snapshot XML.
It's written nowhere that those features will disappear if not added in
the XML, but we can't control that for active or internal snapshots.
The same applies when such features are requested and the snapshot is
active or internal.

The patch looks good, conditional ACK if the check is added and if Eric
or Peter will say they want this to be supported in snapshots.  If not,
then we don't have to bother with such dual feature support and can
remove this and the next patch from the series.

Eric, Peter?  What's your opinion on this?

Thanks,
Martin