Bug#753816: [systemd] Broken audio

[Antonio Marcos López Alonso]

El 06/07/14 05:34, Ben Hutchings escribió:
> On Sat, 2014-07-05 at 18:58 +0200, Michael Biebl wrote:
>> Am 05.07.2014 18:38, schrieb Antonio Marcos López Alonso:
>>> El 05/07/14 17:06, Michael Biebl escribió:
>>>> Am 05.07.2014 17:56, schrieb Antonio Marcos López Alonso:
>>>>> Just in case, have you noticed I'm using an ALSA-Jack loopback setting
>>>>> for audio?
>>>> Under sysvinit, udev (including udevadm settle) is started before the
>>>> kmod init script, which loads snd_aloop.
>>>> That means, snd_aloop is loaded after snd_hda_intel.
>>>>
>>>> Under systemd, it looks like the snd_aloop module is loaded about the
>>>> same time systemd-udevd is started. There might be a race here and
>>>> snd_aloop is loaded before snd_hda_intel.
>>>>
>>>> This *might* be the reason, but I'm no expert on this matter.
>>>>
>>>> Can you try removing snd_aloop from /etc/modules and test if that makes
>>>> a difference.
>>>>
>>> OK removed snd_aloop and audio is back. Then reloaded the module,
>>> restarted JACK and audio is still fine. So as you said there must be
>>> some race condition in there. Should I keep this ticket opened?
>>>
>> Hm, not sure what to do about this. We could order
>> systemd-load-modules.service after systemd-udevd.service. But that
>> doesn't guarantee the loading order of the modules and it feels like
>> papering over the underlying issue.
>>
>> I'm no sound expert, but I'd say that the loading order should not
>> matter. Maybe we need some input from the kernel team or some alsa
>> experts here.
> I think this is due to ALSA userland (or maybe higher levels) being
> stupid about device selection.  I think the default is to use sound
> device 0, which can be whichever driver won the race.
>
>> I took the liberty to CC the Debian kernel team and the maintainer of
>> the snd_aloop module. I hope they can help us here.
>>
>> For reference the complete bug report is at [1]
>>
>>
>> Michael
>>
>>
>> [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=753816
> I think the usual workaround is to add 'index=1' to the snd-aloop line
> in /etc/modules.  It is probably possible to do something more
> sophisticated in an ALSA configuration file.
>
> Ben.
>

Adding 'index=1' didn't work. I still have to reload snd_aloop and 
restart JACK to get audio back.

Antonio