Re: [Qemu-devel] [PATCH 0/2] Make mixer emulation configurable at runtime

[Gerd Hoffmann]

  Hi,

> >> 2. Why do we bother providing these devices when CONFIG_MIXEMU off?
> >> 
> >>    Why would anyone want hda audio devices without a mixer?  Why
> >>    wouldn't anyone who wants hda audio devices also want CONFIG_MIXEMU
> >>    enabled?
> >
> > It'll actually work just fine with HDA.  The guest figures there is no
> > volume control and will fallback to do volume control in software then.
> > Net effect is that the audio sample processing to change volume is done
> > by the guest instead of mixemu, so you don't actually save cpu time by
> > turning off mixemu ...
> 
> I don't doubt it works, I doubt anybody would want the software mixing
> done in the guest instead of mixemu so badly that he wants to use a
> special device that makes that possible.

Backward compatibility is the only reason.

> > I think AC97 has broken volume control with CONFIG_MIXEMU=n, because the
> > guest tries to use the non-functional volume controls.
> >
> > So, yes, for serious sound support you want CONFIG_MIXEMU=y.
> 
> Which brings me back to question 1: why is non-serious sound support the
> default?

Last attempt to flip the default was vetoed by malc.

cheers,
  Gerd