Re: Enable audio virtualization in Xen

[Christopher Clark <christopher.w.clark@xxxxxxxxx>]

On Thu, Jul 28, 2022 at 1:37 PM Christopher Clark
<christopher.w.clark@xxxxxxxxx> wrote:
>
> On Thu, Jul 28, 2022 at 12:05 PM SHARMA, JYOTIRMOY
> <JYOTIRMOY.SHARMA@xxxxxxx> wrote:
> >
> > [AMD Official Use Only - General]
> >
> > Hi all,
> >
> > Can anyone please help here?

Hello again,

I have now been able to enable HVM guest audio using the Xen PV audio
front end device drivers that are included in Ubuntu 22.04.
The steps:
- remove the qemu wrapper script from my previous email, if you have
installed it, and restore the original qemu-system-i386 binary
- keep the pulseaudio system configuration from my previous email, so
that tools that run as the root user are able to talk to the desktop
host pulseaudio system
- add a vsnd device to the guest VM configuration file, in this case
using pulseaudio for output:

vsnd = [[ 'card, backend=Domain-0, buffer-size=65536,
short-name=VCard, long-name=Virtual sound card, sample-rates=48000,
sample-formats=s16_le', 'pcm, name=dev1', 'stream, unique-id=pulse,
type=P' ]]

- download, build and run the backend audio tool in the host dom0.

For the backend you'll need to download and build first libxenbe and
then snd_be from:
https://github.com/xen-troops/libxenbe
https://github.com/xen-troops/snd_be

Once you have the snd_be binary built, you can run it as root thus
before starting your guest VM:
./snd_be -v *:Debug
and then the guest audio output should be working OK.

I have not explored using ALSA rather than pulseaudio yet.

Christopher