Re: [Qemu-devel] [PATCH] audio: don't use alsa by default

[Daniel P . Berrangé]

On Tue, Feb 19, 2019 at 11:39:49AM +0100, David Hildenbrand wrote:
> On 19.02.19 11:15, Gerd Hoffmann wrote:
> > ardware is present the driver initializes
> > successfully and throws errors later on, i.e. effectively the
> > automatic probing doesn't work.  So the driver should not be
> > used by default (until that is fixed).  Drop the can_be_default
> > flag.
> > 
> > Explicitly picking the alsa driver (using QEMU_AUDIO_DRV=alsa
> > environment variable) will continue to work.
> 
> Just pointing out that with this patch, audio initialization still
> hinders me from starting guests on my Fedora 29 when running under root
> (I don't think this patch was also intended to fix that, just pointing
> out for me the problem still exists).
> 
> 
> ALSA lib pulse.c:243:(pulse_connect) PulseAudio: Unable to connect:
> Connection refused
> 
> sdl: SDL_OpenAudio failed
> sdl: Reason: ALSA: Couldn't open audio device: Connection refused
> ALSA lib pulse.c:243:(pulse_connect) PulseAudio: Unable to connect:
> Connection refused
> 
> sdl: SDL_OpenAudio failed
> sdl: Reason: ALSA: Couldn't open audio device: Connection refused
> audio: Failed to create voice `pcspk'
> qemu-system-x86_64: Initialization of device isa-pcspk failed:
> Initializing audio voice failed
> 
> 
> For whatever reason, on my Fedora29 root cannot access alsa devices.
> Maybe it is a Fedora 29 problem, maybe only my setup is messed up (e.g.
> because of an upgrade). The workaround for me is to not run QEMU as
> root. (I don't have time to look into the details)

Does your machine actually have any sound card in it ?  ie does
/dev/snd/ report any pcm*  devices ?

Based on your logs here, I suspect it has no sound card. The reason
it will work as non-root, is that QEMU will activate the pulseaudio
backend that works fine [1] even if no sound card is present.



Regards,
Daniel

[1] by "fine" I mean it'll happily accept the audio stream from the app
    and send it to /dev/null :-)
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