[BLFS Trac] #1960: Sound goes to the random card

BLFS Trac trac at linuxfromscratch.org
Sun May 7 02:16:58 PDT 2006


#1960: Sound goes to the random card
--------------------------------------------+-------------------------------
 Reporter:  alexander at linuxfromscratch.org  |       Owner:  blfs-book at linuxfromscratch.org
     Type:  task                            |      Status:  new                           
 Priority:  normal                          |   Milestone:  6.2                           
Component:  BOOK                            |     Version:  SVN                           
 Severity:  normal                          |    Keywords:                                
--------------------------------------------+-------------------------------
 After the udev_update merge, the module loading order became random. If
 someone has two sound cards and both drivers are modular, the "default"
 sound card becomes random. I.e., after some boots, the FM801 card is
 treated as the "default" one, and after rebooting it may well be that the
 onboard SBPCI sound card becomes the default. So one cannot predict where
 the sound goes.

 One cannot address this in LFS or BLFS by creating persistent symlinks,
 because ALSA library doesn't allow specification of the output device via
 device node name (i.e., one can create a persistent /dev/snd/pcmIntelD0
 symlink that always points to the right card, but cannot tell ALSA to
 output sound using this symlink).

 I have already complained to LKML about that, and was told to use a
 completely non-standard method for binding the default device to a certain
 card:

 http://lkml.org/lkml/2006/1/5/214

 So there are the following alternatives:

 1) fix the card order in modprobe.conf:

 {{{
 options snd-fm801 index=0
 options snd-ens1371 index=1
 }}}

 2) bind the default device to the correct card in /etc/asound.conf:

 {{{
 pcm.dsp0 {
     type plug
     slave.pcm "dmix:FM801AU"
 }
 }}}

 3) Don't rely upon udev to load ALSA drivers, do that by hand in
 /etc/sysconfig/modules so that the order becomes known and fixed.

-- 
Ticket URL: <http://wiki.linuxfromscratch.org/blfs/ticket/1960>
BLFS Trac <http://wiki.linuxfromscratch.org/blfs>
Beyond Linux From Scratch



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