sbc: isa plug-n-play

Andriy Gapon avg at
Fri Feb 22 16:34:56 UTC 2008

I have an older hardware system with a newer OS on it :-)
It's i386 7.0-RC1 on 440BX / Pentium III.
I have the following soundcard in ISA slot on the system:
sbc0: <Creative SB AWE64 Gold> at port
0x220-0x22f,0x330-0x331,0x388-0x38b irq 5 drq 1,5 pnpid CTL00b2 on isa0
sbc0: [ITHREAD]
pcm0: <SB16 DSP 4.16> on sbc0

I believe that the soundcard supports ISA Plug-n-Play.

Everything works great. But recently I had an itch to go trough BIOS
settings. I spotted one named "Plug-n-Play OS" and it was set to
disabled. I thought "what the heck" FreeBSD is a Plug-n-Play OS for a
long time, so flipped it to enabled.
After that no joy, the soundcard stopped to work. It was detected as
before, there is no difference in dmesg whatsoever, but it did not
generate any interrupts (verified with vmstat -i). And any playback
attempt resulted in zero sound and the following message on console:
pcm0:virtual:dsp0.vp0: play interrupt timeout, channel dead

So I disabled the option again and everything is fine.
Practical conclusion: don't do it.
Question of curiosity: what is it that BIOS can do with this card that
our driver can not ?

Andriy Gapon

More information about the freebsd-multimedia mailing list