Re: [virtio-dev] virtio-snd spec question

[Stefan Hajnoczi <stefanha@redhat.com>]

On Tue, Feb 01, 2022 at 03:57:10PM -0800, Roman Kiryanov wrote:
> Hello,
> 
> I work in Android Studio Emulator and I am currently implementing a
> virtio-snd device. We found a spec draft here:
> 
> https://github.com/oasis-tcs/virtio-spec/commit/e73c8cdf3e822fd83c26c6de964a947670f93cc3#diff-73045e70aeaf45f93087610437b705e2d320c82a9d29b4027721f5f5f3918dc5
> 
> It mentions four virtqueues: ctl, event, rx and tx. It is not very clear
> where a virtio-snd device should put responses to the ctl requests from the
> linux kernel driver. There is a kernel driver implementation and we have a
> virtio-snd device implemented in another emulator, it uses the same
> virtqueue (ctl) to put ctl responses and the current kernel driver seems
> happy with this.
> 
> Do you know if this is expected behavior? I am far from an expert here, but
> I believe the device and the kernel will race here by reading from the same
> virtqueue: the device could read VirtQueueElement produced by itself before
> the kernel if the kernel is not fast enough.

CCing Anton and Shreyansh.

Stefan

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