snd_hda

[Sascha Wildner]

On Fri, 12 Oct 2012 23:13:25 +0200, Goetz Isenmann  
<info at goetz-isenmann.de> wrote:

> On Fri, Oct 12, 2012 at 09:47:51PM +0200, Sascha Wildner wrote:
>> .... Put:
>>
>> hw.snd.hdac.msi.enable=0
>>
>> in loader.conf.
>
> When I put only "hw.snd.hdac.msi.enable=0" into loader.conf, I can't
> query this value:
>
> $ sysctl hw.snd
> sysctl: unknown oid 'hw.snd'

Without snd_hda loaded, the tunable does nothing.

> After "kldload snd_hda" I get:
>
> $ sysctl hw.snd
> [...]
>
> and ugly sound.

In this case, it's probably still enabled (if the hardware supports it),  
as the tunable will not affect it without being loaded by the loader or  
being in the kernel.

> When I then add 'snd_hda_load="YES"' to loader.conf, I also see
> nothing about msi but as before:
>
> $ sysctl hw.snd
> [...]
>
> and I get no sound but an error message from mplayer:
>
> [AO OSS] audio_setup: Can't open audio device /dev/dsp: Operation not
> supported by device

If snd_hda_load is in loader.conf, but the MSI tunable is not, it works?  
If so, that's weird. Disabling MSI should not affect that.

In any case, you can check if MSI is used or not either from the dmesg or  
by looking at pciconf -lvc output:

cap 05[a0] = MSI supports 1 message, 64 bit

means no MSI enabled.

cap 05[a0] = MSI supports 1 message, 64 bit enabled with 1 message

means it is enabled.

Sascha