[ydl-gen] Sound on G4 PowerMac (digital audio)

[Stephen Harker]

Hi Derick,

> Within XFCE there is an app accessible by going to the XFCE menu or by
> right-clicking on a three-button mouse: Other --> Soundcard Detection.
> [...]

It sounds pretty much like the standard system-config-soundcard.  As I
indicated sound works perfectly in my iBook G4.  This is available
from the command line or any GUI.  Personally I use a minimal fvwm2
and run most things from the command line.  The question I was asking
was related to whether the original poster was using the correct
module.

With my 7600/200 the snd-powermac module is the correct module.  With
my iBook G4 and Powermac G5 it is snd-aoa (I have sound working
perfectly on all three of these machines).  If you look into the
information on the kernel (for example using `make xconfig') you will
find that snd-aoa is the appropriate module for later Powermacs and
snd-powermac for earlier ones.  At the time of my email I was unsure
which of snd-powermac or snd-aoa was appropriate for a `digital audio'
model, mostly because I did not know what that model name represented.
Looking at Apple Spec did not list the sound chip.  The notes in the
kernel indicate what sound chip goes with which module.

As I later indicated I finally found reporta that made it clear that
the `digital audio' G4 model uses the 'tumbler' device.  This is
listed in the kernel notes as a device for which the snd-powermac
module is appropriate.  It would appear to be the last sound device
for which that is the appropriate module.  Later sound devices require
snd-aoa.

If you look you will find many bug reports in which people report that
a kernel in which both snd-aoa and snd-powermac modules exist tends
not to provide sound in later macs.  What seems to happen is that the
kernel insists on using snd-powermac rather than snd-aoa and no sound
is generated.  This was certainly my experience with the default
kernels for ydl6.2 and with self-compiled kernels.  For these later
machines it is far more reliable if you compile the kernel without
snd-powermac, then sound works reliably all the time.

At the time of my first email I was not sure whether the original
poster had a machine that should be using snd-aoa.  In this case, as
is well known, snd-powermac would prevent sound working.  This would
have explained why he was seeing the module being loaded, but not
getting any sound.  It turns out not to be the case as snd-powermac is
appropriate for the `digital audio' machine.

The problem with snd-aoa and snd-powermac not coexisting reliably
appears to continue in kernels as late as 2.6.33 (I am using a version
of this in my G5).

> This report collects all elements for you regarding the sound device
> you have installed.  What is useful about it is that different sections
> list the commands used to generate the data below it.  This can be a
> time saver when one is looking to resolve a problem.

Personally I find it easier and quicker to use dmesg and related
commands (such as those listed in the report) directly from the shell.  

-- 
Stephen Harker                           s.harker at adfa.edu.au
PEMS                
UNSW at ADFA