[alsa-devel] [RFC][PATCH 0/2] ALSA: control: limit life time of user-defined element set

[Takashi Iwai]

On Sun, 04 Sep 2016 17:38:20 +0200,
Clemens Ladisch wrote:
> 
> Takashi Sakamoto wrote:
> > ALSA control core allows applications to add arbitrary element sets to an
> > instance of control device, while removal of the element sets is voluntarily
> > done by some applications. This is not convenient to certain situations.
> 
> This was originally designed for softvol, where the user-defined element
> should behave as much as possible as a hardware control.
> 
> > My large concern is whether there's any applications to open a file descriptor
> > just to add any element sets.
> 
> alsactl restore

Yes, and this is actually 99% of use cases for now: restoring the
persistent softvol element at the boot time.

A similar idea to implement a process-bound user-space kctl has popped
up a few times in the past, but it's never realized, since no one
could find it really useful / demanded.  You may say that it can be
used for some application-specific volume or such, but what would be
it exactly?

Once when we have a real use case, I'm not against adding such a
change.  But of course as long as it doesn't break the current way of
softvol usage with the persistent user kctl.


thanks,

Takashi