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. -- Ben Hutchings The most exhausting thing in life is being insincere. - Anne Morrow Lindberg
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