udev rules and Sound Cards Squeeze
After the upgrade from lenny to squeeze, the sound cards
and CDROM's got all scrambled. The upgrade automatically
generated rules for the CDROM's so those worked after a bit of
tweaking on the symlink path. The two sound cards on the system
need the same attention but no automatic rules were generated so
I am not sure what they will look like.
After unsuccessfully trying to play a sound file which
mplayer said should be playing, I checked the output of the
secondary sound card which is an AWE64 Gold and there it was
playing at a very low speed. arecord -l listed a SB16 as the
primary sound card and no others so things were really messed up
to say the least.
I went to /etc/udev and did
grep -r -i audio *
which is one of my favorite trouble-shooting techniques when
weird stuff happens and found that there is a file in /etc/udev
called
libmtp7.rules
The very first line says to put this file in rules.d and it
wasn't there so I did.
After a reboot, the first sound card which is a CS4236B
mounted on the mother board was now the primary sound card and
seems to be working perfectly so I did get that card back. The
AWe64 is now not listed if one does a arecord -l command.
Both the CS4236B and SB16AWE64Gold do show up by name in syslog
after a reboot and they both used to work under lenny so I
imagine the SB16AWE will rise again if the right rules are used.
The libmtp7.rules file does not mention any sound cards by name
but appears to take care of the permissions that can keep
non-root users from accessing /dev/dsp among other things. After
installing that file in the right place, /dev/dsp became
accessible from a user account that belonged to the audio group.
Things now act right except for no second sound card
yet. What can I do to either generate sound card rules or find
some already-generated sound card rules that can be addapted to
this system?
When things are working again, there should be /dev/dsp0
and /dev/dsp1. This is where udev should truly shine as there
used to be a race condition which could cause the wrong sound
card to be first or the second sound device to not always make
correctly after a reboot.
Both the CS4236B and AWE64 Gold show up in the PNP
report in syslog so they do not list as PCI devices.
Thanks for any help about how one generates rules for
sound cards.
Martin McCormick
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