F11: OSS and pulseaudio conflict

Warren Togami wtogami at redhat.com
Sun Nov 30 05:29:22 UTC 2008

Bastien Nocera wrote:
>> There's no sound mixing (through ALSA or PulseAudio) when OSS emulation
>> is used in ALSA. Kill it (and file a bug against the app).
> Filed:
> https://bugzilla.redhat.com/show_bug.cgi?id=472741

CUSE: Character devices in user space

The first cuse driver is an OSS proxy to pulseaudio, that provides 
/dev/dsp, /dev/adsp and /dev/mixer.  The article describes it as likely 
to be merged in the upstream 2.6.29 kernel.  Let us help this become 
stable so we can count on it for F11.

Assuming cuse OSS proxy is ready for F11, and it works reasonably well 
as a complete replacement for ALSA's OSS compat layer, we would do the 

1) Disable building of the OSS kernel modules.
2) Provide cuse OSS proxy in its own package, that starts the OSS proxy 
upon user login after the user's pulseaudio daemon is running.
3) Do NOT install it by default, as it is yet another process that runs 
that few people actually need.  If people want OSS proxy they can 
install this optional package.

The fallback plan if cuse OSS proxy is not ready for F11...

1) Keep the OSS kernel modules.
2) alsa-plugins-pulseaudio ships /etc/modprobe.d/blacklist-oss-sound, 
thereby preventing loading of these kernel modules and interfering with 
pulseaudio daemon.
3) If the user wants to use an OSS sound application they can use padsp 
4) Native OSS comes back if the user uninstalls alsa-plugins-pulseaudio, 
which also makes it so nothing uses pulseaudio for sound output by default.

In both cases the user has to manually do something to use OSS, which is 
fine by me.

Tracking this for F11 here.

Warren Togami
wtogami at redhat.com

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