Re: [virtio-dev] virtio-snd comments/questions

Manos Pitsidianakis
2023-11-10T08:24:01Z

On Thu, 9 Nov 2023 at 18:46, Radu Ocica <rocica@blackberry.com> wrote:
> >> This looks promising. I found it already at https://urldefense.com/v3/__https://github.com/torvalds/linux/blob/master/sound/virtio/__;!!JoeW-IhCUkS0Jg!bBq1USPrJoN1_CBJkW-XBknkCSEOUP40V1ctr_OU0tsYyEr9pXjSEu7n5ibc5BL4fKT3Utk-cpGw6FiWxDY$ and will give it a try. Is there a repository for this driver code where both this fix and the audio control support is available?

The patch will most likely be part of the next kernel release, 6.7. As
for the control support, read on:

> > What do you mean with audio control support? Are you talking about the
> > device? The device implementation is at
> https://urldefense.com/v3/__https://github.com/rust-vmm/vhost-device/tree/main/staging__;!!JoeW-IhCUkS0Jg!bBq1USPrJoN1_CBJkW-XBknkCSEOUP40V1ctr_OU0tsYyEr9pXjSEu7n5ibc5BL4fKT3Utk-cpGw1sNq6IY$ .
>
> I meant the support for feature VIRTIO_SND_F_CTLS in the virtio_snd guest driver. A patch to add this support is available here: https://lists.oasis-open.org/archives/virtio-comment/202104/msg00013.html. However this patch is not present in the virtio_snd guest driver version here: https://urldefense.com/v3/__https://github.com/torvalds/linux/blob/master/sound/virtio/__;!!JoeW-IhCUkS0Jg!bBq1USPrJoN1_CBJkW-XBknkCSEOUP40V1ctr_OU0tsYyEr9pXjSEu7n5ibc5BL4fKT3Utk-cpGw6FiWxDY$ . I was wondering whether there is a repository where the virtio_snd driver has both the VIRTIO_SND_F_CTLS support and the ack callback patch.

The feature is part of the 1.3 version of the VIRTIO spec which is
still in a Committee Specification Draft phase. You can find that the
latest version of the VIRTIO spec is 1.2 here:
https://www.oasis-open.org/committees/tc_home.php

I believe it will take some time for both 1.3 to be approved and
afterwards patches for the kernel must be published and reviewed,
which will take some cycles as well. So I'd suggest you not to count
on control capabilities at the moment, unfortunately.

--
Manos Pitsidianakis
Emulation and Virtualization Engineer at Linaro Ltd