[pulseaudio-discuss] Needed kernel modules for pulseaudio

[Sean McNamara]

Hi,

Michael Schöller wrote:
> I'm really sorry if this is the wrong place to ask or if this question 
> was already answered 100 times before but I did not find anything about 
> this.
>
> I'm running Fedora9 on an PS3. I configured pulseaudio and with the 
> default kernel sound is running fine. Now I want to compile my own 
> kernel. So I download the newest kernel sources from the ps3 kernel tree 
> and created an config file with make ps3_defconfig. Well with this 
> kernel sound aplay is working so sound support seems to be ok. The 
> problem is that it looks like pulse audio is not finding the sound 
> device. The mixer applet in gnome stop working too.
> So my question is what have to be activated in the kernelconfig, so that 
> pulseaudio (or maybe audio, I'm not really sure if this is an pulseaudio 
> problem) is working again. Maybe it has something to do with HAL support 
> but I know really nothing about that stuff so I hope some "sound 
> experts" could give me an Hand.
>   
If aplay works then you have the ALSA kernel modules loaded. Without 
further info, I can't be sure of what the problem is. However... it's 
possible that your alsa-lib (all files matching the pattern 
/usr/lib/libasound.* and within the directory /usr/lib/alsa-lib) is now 
version-mismatched with your ALSA kernel modules. ALSA is both in 
userspace and kernelspace. If you updated your kernel but not ALSA 
libraries, a version mismatch may exist.

ALSA builds in some degree of version mismatch tolerance, but if the 
difference is too extreme, some things will be broken. When kernel API 
updates are pushed, Linus prefers that the APIs themselves can't break 
backwards compatibility. It's easy to gloss over some semantic changes, 
though, even when the API prototypes are the same.

So something extremely simple like aplay may not have an issue; but 
pulseaudio makes _extensive_ use of just about every API of alsa-lib, 
and cares very much about corner cases and nitty-gritty. I imagine that 
a substantially old alsa-lib will not know how to properly interface 
with substantially new ALSA kernel modules.

My first suggestion would be for you to upgrade your version of alsa-lib 
to the latest stable from alsa-project.org. Build instructions for ALSA 
are on their wiki, and outside the scope of this ML anyway.

If that doesn't work, give us more debugging info. To give us more 
debugging info, there are a variety of things you can do; but if you 
want to flood us with extraneous stuff to sort through all in one go, 
you can post the output of running the following in a shell:

pulseaudio --daemonize=false -vvv

and

aplay -v /path/to/a/soundfile/on/your/ps3.wav

and

pulseaudio --dump-conf

and

cat /etc/pulse/default.pa
#Or any other way you can get the contents of this file to us.

Note: This issue is not a one-off but a troubleshooting issue, requiring 
many round trips of asking you to try things and getting the output. You 
can resolve this much quicker on IRC: chat.freenode.net, #pulseaudio

Thanks,

Sean
> Well since I'm nearly clueless when it comes to kernel debugging some 
> may ask why I was trying. Well the reason is simple. The default kernel 
> works but is really lame on an PS3 the kernel made with "make 
> ps3_defconfig" is much faster but lacks sound support as described (and 
> graphic support if you don't activate PCI support in the kernel 
> config<-bug in xorg)
>
> Michael
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