Re: [Qemu-devel] [RFC PATCH] qapi for audio backends

[Kővágó Zoltán]

2015-06-04 09:43 keltezéssel, Gerd Hoffmann írta:
> > +#
> > +# @mmap: #optional try using memory mapped access
>
> IIRC this doesn't work everywhere, especially when the oss api is
> implemented as library.
>
> Linux had that, but on linux everybody uses alsa these days ...
> Dunno about other platforms.

idk, the code tries to mmap first, and if it fails, falls back to non 
mmapped access. But something is broken there, as with QEMU_OSS_MMAP=1 
it fails (on linux with alsa oss emulation with pulseaudio alsa 
emulation...). But it ought to work on linux, according to the comments. 
Maybe it needs the native oss, and not the alsa emulation.

> > +# @exclusive: #optional open device in exclusive mode (vmix wont work)
> >
> > +# @dsp_policy: #optional set the timing policy of the device, -1 to use 
> > fragment
> > +#              mode (option ignored on some platforms)
>
> Would be interesting to know on which platforms this actually has an
> effect (both options) ...

From a quick google it looks like whatever platform that have oss4 (the 
dsp_policy). exclusive just adds O_EXCL to open flags.

> IIRC 'vmix' was a feature of the commercial, ossaudio driver package.