vchans seem to affect /dev/dsp* availability

[Dan Naumov]

On Sun, 27 Apr 2003 17:30:53 -0700
"Cliff L. Biffle" <cbiffle at safety.net> wrote:

> When I have vchans enabled, every few attempts at opening /dev/dsp*
> result in 'Operation not supported by device.'  Also, while they're
> enabled, some programs (most reproduceably artsd) peg my CPU after
> outputting sound data in certain situations.
> 
> Disabling vchans fixes the problem.  The problem's a little ephemeral,
> so I'm still collecting hard data, but it seems I have to go all the
> way to properly disable them, e.g.
> kldload snd_pcm
> sysctl hw.snd.maxautovchans=0
> kldload snd_<my card>

Here is a related PR initially submitted on July 17, 2002:
http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/40711

I am experiencing this problem on a 5.0 box (as I've described in the
follow-up to this PR). Disabling and then re-enabling vchans seems to
work as a workaround, although sometimes I have to do it several times.

Sincerely,
-- 
Dan Naumov <dan.naumov [at] ofw.fi>