Re: [RFC] modular dependencies for kvm's qemu

[Carlo Marcelo Arenas Belon <carenas-kLeDWSohozoJb6fo7hG9ng@public.gmane.org>]

On Tue, Oct 16, 2007 at 10:36:03AM -0500, Carlo Marcelo Arenas Belon wrote:
> On Tue, Oct 16, 2007 at 04:20:37PM +0200, Avi Kivity wrote:
> > Carlo Marcelo Arenas Belon wrote:
> > >  
> > >>It seems like rather
> > >>a bad idea to suddenly switch the configure script defaults in the way 
> > >>you suggest for alsa. It really wouldn't be much harder to set 
> > >>enable_alsa=1
> > >>in the top of configure, and then have the flag toggle it to off.
> > >
> > >ok, but if that is added to kvm's configure then the logic will be inversed
> > >when looking at qemu's configure, probably confusing users.
> > 
> > If audio output is going to sdl anyway, then this has no effect on most 
> > users, right?
> 
> it probably wouldn't work out of the box, unless they change
> 
> QEMU_AUDIO_DRV=alsa
> 
> to :
> 
> QEMU_AUDIO_DRV=sdl
> SDL_AUDIODRIVER=alsa
> 
> but I never had sound support configured so I am no way expert and can't test
> if that is the case or if that is the way it fallsback (will take a closer
> look at the code later though).

for the cases where qemu doesn't have alsa support but the environment
variables point to using alsa, then it will complain with :

  audio: Unknown audio driver 'alsa'
  audio: Run with -audio-help to list available drivers

but then it will scan for an available audio driver it can use by default and
configure SDL instead, probably with alsa support if that is available, as 
done explicitly by the second set of environment variables.

tested it with a 64bit linux host running a 32bit windows 2000 advanced server
guest using -soundhw sb16.

in a hopefully unrelated note, using alsa directly wouldn't work as well as
using alsa through SDL, so I guess that the impact on the users is actually
positive if using SDL is also more reliable.

anyone with more audio experience care to comment?

Carlo

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