How to debug the sound driver?

Peter Much pmc at
Thu Mar 31 01:33:22 PST 2005

Hi all,

from Release 5.2.1 to 5.3 there were changes done at the soundcard
support. (The release-notes say so.)

Now my soundcard does not work anymore with 5.3.
I have carefully studied the manpages (sound and snd_sbc), and did
not find out what I could have done wrong.

Now I am in the need some information or suggestions about how to 
debug this problem. I did not find useful debug switches in the driver 
sourcecode, or other useful approach.

The soundcard is ESS ES1869 based ISA bus card.
It should work after loading "sound" and "snd_sbc" (and did so until
I do not get any errors when loading "sound" and "snd_sbc".
When loading "snd_sbc", the kernel issues a one-line message that it 
found the ESS ES1869 (and all the io-ports and irq and dma). This
message is literally the same that I was seeing since Release 4.4,
so this part seems ok. I also get the interrupt 5 assinged to sbc1.

But the "sound" driver does not recognize the card anymore. In 
/dev/sndstat it shows no devices installed, and there are no "dsp" 
devicenodes. But since /dev/sndstat is present (and also some
sysctl variables), it seems that "sound" also got operative.

There is no problem with the hardware - I can reboot to Release 4.4,
and it is still working there.

>From my impression, the problem could be somewhere with the "sound"
driver. I would like to find out what is going wrong, but my main
difficulty is I have no idea about the logical-flow-of-functionality
there - especially how "sound" and "snd_sbc" are supposed to inter-

I reported to freebsd-multimedia, but did not get an answer.

Now, before I go the hard way analyzing changes via commitlog
(actually I never had reason to understand how the sound system
is implemented - it just worked), I would much appreciate any
idea about more straight-forward approaches.


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