Re: [PATCH v2 11/13] audio: deprecate -soundhw pcspk

[Gerd Hoffmann <kraxel@redhat.com>]

On Mon, May 18, 2020 at 11:26:50AM +0100, Daniel P. Berrangé wrote:
> On Mon, May 18, 2020 at 12:16:28PM +0200, Gerd Hoffmann wrote:
> > On Fri, May 15, 2020 at 05:08:23PM +0200, Ján Tomko wrote:
> > > On a Friday in 2020, Gerd Hoffmann wrote:
> > > > Add deprecation message to the audio init function.
> > > > 
> > > > Factor out audio initialization and call that from
> > > > both audio init and realize, so setting audiodev via
> > > > -global is enough to properly initialize pcspk.
> > > > 
> > > > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> > > > ---
> > > > hw/audio/pcspk.c | 24 +++++++++++++++++++++---
> > > > 1 file changed, 21 insertions(+), 3 deletions(-)
> > > > 
> > > > @@ -236,9 +245,18 @@ static const TypeInfo pcspk_info = {
> > > >     .class_init     = pcspk_class_initfn,
> > > > };
> > > > 
> > > > +static int pcspk_audio_init_soundhw(ISABus *bus)
> > > > +{
> > > > +    PCSpkState *s = pcspk_state;
> > > > +
> > > > +    warn_report("'-soundhw pcspk' is deprecated, "
> > > > +                "please set a backend using '-global isa-pcspk.audiodev=<name>' instead");
> > > > +    return pcspk_audio_init(s);
> > > 
> > > -soundhw pcspk is the only soundhw device present in libvirt git.
> > > 
> > > Is there a way to probe for this change via QMP?
> > 
> > Oops.  I'm surprised libvirt actually supports pcspk.
> > 
> > There is no way to see that in qmp, and I can't think of an easy way
> > to add that.  Does libvirt check for command line switches still?
> > So it could see -soundhw going away if that happens?
> 
> IIUC, instead of probing for whether -soundhw is deprecated, it should
> be suffiicent for us to probe if "isa-pcspk.audiodev" exists. Assuming
> we always use isa-pcspk.audiodev if it exists, then we'll trivially
> avoid using the -soundhw arg.

It's not that easy unfortunately.  We have .audiodev for a few releases
already.  But just setting that isn't enough to initialize pcspk in
current qemu, "-soundhw pcspk" is still needed ...

I'm looking at how to initialize onboard audio devices currently, maybe
the best way to handle that is to do it flash-style with machine
properties (i.e have a pc.pcslk alias for pcspk.audiodev, simliar to
pc.flash0 being an alias for pflash.drive).  That'll be better that
-global and it'll also be visible in QOM.

Initialization order looks tricky though.  I'd have to create pcspk
early, simliar to flash, in pc_machine_initfn().  Problem is I don't
have a isa bus yet at that point (flash is sysbus and doesn't have this
problem).  I'm open to suggestions hiow do deal with that best.

take care,
  Gerd