[PATCH v2] docs: domain: document legacy audio for qemu

[Andrea Bolognani]

On Wed, Jan 12, 2022 at 01:42:00PM +0100, Olaf Hering wrote:
> Adding a blurb like this was forgotten in 2009.

How did you come up with 2009? Not questioning it, just curious :)

> +Note:
> +If no ``<audio/>`` element is defined, and the ``graphics`` element is set to
> +either 'vnc' or 'sdl', the libvirtd or virtqemud process will honor the following
> +environment variables:
> +
> +* ``SDL_AUDIODRIVER``
> +
> +  Valid values are 'pulseaudio', 'esd', 'alsa' or 'arts'.
> +
> +* ``QEMU_AUDIO_DRV``
> +
> +  Valid values are 'pa', 'pulseaudio', 'none', 'alsa', 'coreaudio', 'jack',
> +  'oss', 'sdl', 'spice' or 'file'.

The fact that we accept "pulseaudio" as an alias for "pa" and expect
"file" instead of "wav" are an unfortunate implementation detail and
a bug respectively. I have just posted patches addressing the
latter[1], and I don't think the former should be documented even
though it's technically accepted, especially considering that we're
talking about legacy settings and we want users to use the <audio>
element instead.

For the SDL part, since we don't have to deal with any of the
conversion shenanigans in that case, I would suggest avoiding the
list and using something like

  Valid values are those accepted for the ``driver`` attribute of
  the `SDL audio backend <#sdl-audio-backend>`__.

instead. But your version works fine too if you're keen on keeping
it as is :)


[1] https://listman.redhat.com/archives/libvir-list/2022-January/msg00738.html
-- 
Andrea Bolognani / Red Hat / Virtualization