Okay, so here's the situation.

I have a powerbook (G4, ppc7450), that had osx 10.3 installed on it for a while. I got ticked off at the lack of good X support on OSX (most of my favorite apps like kate and gaim are X), so I tried to dual boot. Since I was unable to resize my one HFS+ partion, I simply wiped it. I then partitioned it as follows:

15 gigs gentoo
15 gigs osx
rest: DMZ FAT

I decided to go with linux first, so I installed it and got it (and ALSA) configured to my satisfaction. However, after installing OSX, my sound (in linux, osx sound is fine) started having problems. I can hear it somewhat with headphones, and barely at all with the builtin speakers (though a little bit). I'm guessing that OSX saves its volumes settings to the hardware which is somehow messing up ALSA, but what can I do to solve it? I've tried shutting OSX down with full volume, and with no volume (and muted) to no avail.

Any ideas?

Sound works by default. When you go into KDE, sound volume by default is set to zero and you can run "kmix" and set it accordingly. Also, when KDE starts up, you get an error that can be ignored. I have no fix for it yet.

Do a CTRL-P and you should see the "Audio I/O Plugins" and enable "AudioCD Reader 0.11d (libcdread.so)" plugin and disable "CD Audio Player 1.2.7 (libcdaudio.so)". Under "Output Plugin", select "OSS Driver 1.2.7 (libOSS.so)" option.


quote from : http://home.pcisys.net/~bpc/laptop/ibook.html

Might be that your volume is just default zero?

Actually, to determine if this is hardware-related, go into osx and turn the volume up.
Then boot back into Linux and tell us what happens.
Of course, the solution above works.