Re: [Qemu-devel] [PATCH 2/3] block: add block_backup QMP command

[Stefan Hajnoczi]

On Mon, Apr 29, 2013 at 09:51:47AM -0600, Eric Blake wrote:
> On 04/29/2013 03:27 AM, Paolo Bonzini wrote:
> > Il 29/04/2013 09:21, Stefan Hajnoczi ha scritto:
> >>> I'd really love to see us change 'BlockJobInfo' to use an enum for
> >>> 'type', instead of its open-coded 'str'.  Likewise, the block-job
> >>> related events in QMP/qmp-events.txt should be updated to refer to the
> >>> enum instead of also being open-coded 'str'.
> >>
> >> Since the block job QMP API has been in released I'm not sure changing
> >> this is worthwhile.  QEMU and libvirt would have to maintain
> >> compatibility so the code will just be duplicated.
> > 
> > I don't think this would change the actual data on the wire.  However,
> > it would let libvirt know the supported block job types by introspecting
> > the enum.
> 
> Until we have introspection, the point is moot.  When we have
> introspection, libvirt would much rather see an enum than a 'str'.  I
> see absolutely no back-compat problem in changing the code to be
> type-safe prior to the point that introspection is added.

Okay, I haven't looked at how QAPI enums are implemented.  If we can
move from custom strings to enum without breaking existing libvirt, then
great!

Stefan