[alsa-devel] How to package the smixer modules?

[Takashi Iwai]

On Mon, 07 Nov 2016 13:43:49 +0100,
Tanu Kaskinen wrote:
> 
> Hi all!
> 
> What do the smixer modules do? I mean these files:
> 
> /usr/lib/alsa-lib/smixer/smixer-ac97.so
> /usr/lib/alsa-lib/smixer/smixer-hda.so
> /usr/lib/alsa-lib/smixer/smixer-sbase.so
> 
> Should they always be shipped along with the main libasound library? I
> maintain the alsa-lib package in OpenEmbedded, and currently
> OpenEmbedded has separate packages for libasound and the smixer
> modules, and I wonder if that's a good idea. It looks like the smixer
> modules don't get installed by default when libasound is installed.
> Debian, in contrast, ships the smixer modules in the libasound package.
> 
> After studying the source code a bit, it seems that the smixer modules
> are dynamically loaded by the "simple mixer" interface of libasound.
> I'm not familiar with the purpose of that interface. I don't know if
> there are many applications that use that interface, and I don't know
> if those applications that do use it suffer badly if the smixer modules
> aren't installed.

The simple mixer is another layer in ALSA mixer API, and actually it's
mandatory.  So, at least, sbase plugin should be provided always when
alsa-lib mixer API is used.  Other plugins are basically never used
practically.

It doesn't matter whether to package them separately or not.  The only
point is that sbase plugin should be available when alsa-lib mixer API
is used.


Takashi