[PATCH] sound(4) related manpages 5.3 TODO item

Ruslan Ermilov ru at freebsd.org
Sun Aug 29 12:06:00 PDT 2004

On Sun, Aug 29, 2004 at 06:08:16PM +0200, Marc Fonvieille wrote:
> On Sat, Aug 28, 2004 at 05:25:03PM +0300, Ruslan Ermilov wrote:
> > One and most important thing I'm not sure I understand, and
> > that's causing a lot of confusion, is why "device pcm" was
> > renamed to "device sound" in the first place?  I believe the
> > reason is that "device sound" is a generic sound driver,
> > which has support for PCM playback, mixer, /dev/sndstat,
> > eventually MIDI, sequencer, and so on.  Individual sound
> > drivers are free to implement either of these interfaces.
> > Most of them implement "pcm" nowadays, so saying that
> > "pcm was renamed to sound" is not quite correct.  In other
> > words, the sound.ko module provides the infrastructure for
> > more than just PCM, and the sound(4) manpage should eventually
> > document more than just PCM.  Does that sound correct?
> >
> I'm not a sound(4) expert, but I think you're right.
> However, I see something that may be confusing for the new comer: in the
> kernel we add:
> device sound
> device snd_ich 		# as example
> and in /dev/sndstat we see:
> FreeBSD Audio Driver (newpcm)
> Installed devices:
> pcm0: <Intel ICH3 (82801CA)> at io 0xd800, 0xdc80 irq 5 bufsz 16384 kld
> snd_ich (1p/2r/0v channels duplex default)
> or in dmesg:
> pcm0: <Intel ICH3 (82801CA)> port 0xdc80-0xdcbf,0xd800-0xd8ff irq 5 at
> device 31.5 on pci0
> pcm0: [GIANT-LOCKED]
> pcm0: <Cirrus Logic CS4205 AC97 Codec>
> Are the "pcm0" and "newpcm" words totally correct here, why no sound/snd ?
It's my current understanding that pcm(4) is only one part
of the sound(4) subsystem.  midi(4) will be another part of
it, and mixer(4) is another such device.  The sound(4) man
page should eventually document the entire sound subsystem.
The snd_foo(4) module can register with the sound(4) system
one "pcm" device, one "midi" device, and one "mixer" device.

> > Does that look sane?  I'd be grateful is someone more fluent with
> > our sound subsystem could review this.
> > 
> I'm not more fluent than you, but your changes seem correct.
Thanks, Marc.  I will wait for one more day, then if nothing
changes, will order repo-copies and proceed with the patch
and merging this to RELENG_5.

Ruslan Ermilov
ru at FreeBSD.org
FreeBSD committer
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