Re: [Xen-users] Xen kernel prevents ALSA working

[Tim Post <tim.post@xxxxxxxxxxxxxxx>]

On Tue, 2007-03-20 at 18:09 +0100, xen.mexon@xxxxxxxxxxxxxxx wrote:
> I'm using Xen under Debian Etch.  I've managed to get my virtual 
> machines working and I'm happy with that.  But I find that if I boot 
> Debian using the Xen kernel (version 2.6.18-4-xen-686), ALSA suddenly 
> can't find either of my soundcards (an AC97 on the motherboard and an 
> M-Audio M44 PCI card).  Everything else seems to work fine, networking 
> and bluetooth and so on.  If I revert to the stock 2.6.18 kernel, ALSA 
> has no problems.
> 
> One thing that I thought could be the problem is the fact that I'm using 
> a 686 kernel, when I'm running on an Athlon processor and really should 
> be using k7.  Unfortunately Debian doesn't seem to have any Xen kernels 
> for k7 at the moment.  But I also tried using the normal 686 kernel, and 
> ALSA works fine under that too, so it seems like it shouldn't be a 
> problem with the wrong architecture.
> 
> I've tried shutting down the xend server, but that doesn't help.
> 
> I notice that all the correct kernel modules for my soundcards are 
> loaded.  ALSA just doesn't see them, somehow.  It might be that Xen has 
> reserved the soundcards for its own use, on the grounds that it might 
> need them to provide virtual hardware to its guest OSs.  But googling 
> around, it seems Xen doesn't even attempt to provide that kind of 
> virtualisation as yet.
> 
> Anyone have some hints for me?
> 
> Thanks,
> Mat
> 
> ___

Really dumb question, but does lsmod give an indication that the modules
for the sound card have been loaded? Are they in /etc/modules?

There's several degrees of broken :

1 - lspci won't see them even with modules loaded, just 'not working'.

2 - lspci sees them, but they still don't seem to work with modules
    loaded

3 - the modules themselves fail to load

4 - (and likely) the modules just aren't loaded on boot

Which one are you experiencing? I've never had a problem getting sound
to work (on dom-0 anyway) under Xen since 3.0 was released on
Debian(ish) distros, but I also build from source. 

I moved over to Ubuntu in Lieu of working with Etch, so I'm not really
familiar with how Debian is packaging Xen now but I believe your old
initrd was handling this for you where your new one is not. Seems to be
the common denominator. 

ALSA should also be screaming about something being wrong during boot,
did you happen to catch any messages from / out of dmesg?

Best,
--Tim



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