the original ad-audiomp branch notes:
Add MP locking to the audio drivers.
Making the audio drivers MP safe is necessary before efforts
can be made to make the VM system MP safe.
The are two locks per device instance, an ISR lock and
a character device lock. The ISR lock replaces calls to
splaudio()/splx(), and will be held across calls to device
methods which were called at splaudio() before (e.g.
trigger_output). The character device lock is held across
calls to nearly all of the methods, excluding some only
used for initialization, e.g. get_locks.
Welcome to 5.99.57.
audio accelerators.
Mixing is done in hardware by the ASSP, but is limited to 4 simultaneous
channels due to the restricted "minisrc" image that we are currently
working with.
Due to limitations in the audio subsystem, I'm currently attaching multiple
'audio' devices to 'esa', one for each voice. Because of this hack, the
default ESA_NUM_VOICES is 1.
fancy, works for the basic output case, but does not support programs
which use playback while going into suspend.
Sketched after code found in FreeBSD and Linux drivers.
chs