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Contents
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News
Restoring mixer levels
Storing mixer levels
Error messages
News
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Last updated 12 April 2009
Restoring mixer levels
----------------------
ALSA drivers initialize hardware mixer levels to zero. It is usually
desirable to set things up so that the mixer levels for basic sound
output are automatically raised to reasonable levels after the drivers
have completed their initialization.
Currently, alsa-utils accomplishes this by having its initscript's
"start" method restore mixer levels to what they were the last time
they were saved (see below). The levels are stored in the file
/var/lib/alsa/asound.state. If either the latter file or the alsactl
program is not available then amixer is used to set mixer levels to
"reasonable" default values.
To set mixer levels to "reasonable" default values from the command
line (i.e., without trying first to restore saved values), run
"/etc/init.d/alsa-utils reset".
For modular drivers on a udev system, the /lib/alsa/udev script runs
the initscript "start" method after a driver has initialized and its
associated control device has been created.
For integral drivers and modular ones loaded very early in the boot
process, the initscript is configured to be run as part of runlevel
initialization. Restoration of mixer levels on bootup can be disabled
by configuring the alsa-utils "service" as stopped in runlevel S. On a
system that uses sysv-rc this means that you should RENAME
/etc/rcS.d/S50alsa-utils to /etc/rcS.d/K50alsa-utils. The symlink
should not be deleted---only renamed.
Storing mixer levels
-------------------------
By default mixer levels are stored before shutdown by the initscript's
"stop" method. The initscript is run with "stop" in runleves 0 and 6.
To disable this behavior, if you are using sysv-rc, REMOVE the
"K50alsa-utils" symbolic links from /etc/rc0.d/ and /etc/rc6.d/.
The symlinks should be removed, not just renamed.
Note that this scheme is different from and simpler than the scheme
that was used by the "alsa" initscript when it contained the code
that implemented mixer level storing and restoring. The runlevels_save
environment variable is no longer used---indeed, there is no
/etc/default/ file for alsa-utils at all---and there is no longer a
choice of values for "alsactl_store_on_shutdown". Now "alsactl store"
is run on shutdown unconditionally; however, this can be disabled by
configuring the alsa-utils "service" as floating in runlevels 0 and 6,
as described above.
Error messages
--------------
If the initscript "start" method is run early in the boot process,
before /usr/ is mounted, then it may print an error message. The
message can be ignored because the initscript gets run again later in
the boot process.
/etc/init.d/alsa-utils: Warning: No alsactl program available.
If you use the snd-cs46xx module then you may see messages like this:
Jan 26 14:32:50 foo kernel: ALSA ../../alsa-kernel/pci/cs46xx/cs46xx_lib.c:427: cs46xx: failure waiting for FIFO command to complete
This arises from a bug in the driver, but so far I have yet to
observe any consequent malfunction in the sound card.
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