On Tuesday 19 August 2008 14:28:24 Hannu Savolainen wrote:
> Yair K. wrote:
> > Hi,
> >
> > I noticed pulseaudio has problems starting when OSSv4 is loaded, and
> > traced it down to using select() and GET{I,O}SPACE with an mmap()'d device
To be more accurate, PulseAudio uses poll() not select().
> > (PulseAudio tries using mmap unless explicitly told otherwise). OSS
> > doesn't support that, and returns -EIO, which is an error code PulseAudio
> > doesn't check for and eventually leads to it failing to start. One might
> > consider blaming Pulseaudio, except:
> >
> > A) These limitations aren't documented anywhere I can see. AFAICT
> > FreeBSD's implementation does support using select(),etc. with mmap().
> > B) OSS's return value isn't entirely consistent: It returns OSS_EIO when
> > select() is used (oss_audio_core.c / oss_audio_chpoll() ), but OSS_EPERM
> > when GETOSPACE is used with mmap. OSS_EIO seems wrong to me - the device is
> > okay, it's just select() isn't supported in the current mode.
> >
>
> The attached diff comments out the error checking. However the result is
> probably that select/poll will never report data available. However
> could you try if it makes any difference with pulseaudio.
What happens is exactly as described - poll() never reports data (it does work
in non-mmaped mode).
Yours,
Yair K.
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