Re: Let's remove some deprecated stuff

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, Apr 29, 2021 at 11:29:42AM +0100, Peter Maydell wrote:
> On Thu, 29 Apr 2021 at 11:28, Daniel P. Berrangé <berrange@redhat.com> wrote:
> >
> > On Thu, Apr 29, 2021 at 12:18:42PM +0200, Gerd Hoffmann wrote:
> > >   Hi,
> > >
> > > >     ``QEMU_AUDIO_`` environment variables and ``-audio-help`` (since 4.0)
> > > >     Creating sound card devices and vnc without ``audiodev=`` property (since 4.2)
> > > >     Creating sound card devices using ``-soundhw`` (since 5.1)
> > >
> > > I think these three should be dropped together, to minimize disruption.
> > >
> > > Where do we strand in terms of libvirt support?  IIRC audiodev= support
> > > in libvirt is rather recent (merged this year).  I'd tend to wait a bit
> > > longer because of that.
> > >
> > > Daniel?
> >
> > Libvirt added supoort for -audio in 7.2.0, release April 4th, so only
> > one month ago.
> >
> > If we drop the features in QEMU in this dev cycle though, this won't
> > impact most users until QEMU 6.1 releases in mid August. I'm perfectly
> > ok with people who use unreleased QEMU git master needing to update
> > their libvirt. The final release date is far enough away that distros
> > will have had new enough libvirt for a good while.
> 
> It does feel to me that dropping the old options now would be being
> a bit over-eager, though. The deprecation cycle time is a minimum, not
> a target :-)

Note the QEMU since has been ready since 4.0, in April 2019 so 2 years.
We dropped the ball on getting this implemented in libvirt, since we
had almost no config options for sound at all in libvirt. We had just
hardcoded 3 sound backends based on the graphics frontend.

So in terms of historic libvirt compatibility, we've only ever relied
on the QEMU_AUDIODRIVER env, none of the other million audio env vars.

IOW, if QEMU was to be conservative, you can drop all env vars except
the main QEMU_AUDIODRIVER.


Regards,
Daniel
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