[virtio-dev] Re: [Stratos-dev] Re: [virtio-dev] Next VirtIO device for Project Stratos?

[Alyssa Ross <hi@alyssa.is>]

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Alex Bennée via Stratos-dev <stratos-dev@op-lists.linaro.org> writes:

> Alyssa Ross <hi@alyssa.is> writes:
>
>> As I understand it, virtio-wayland is effectively deprecated in favour
>> of sending Wayland messages over cross-domain virtio-gpu contexts.  It's
>> possible to do this now with an upstream kernel, whereas virtio-wayland
>> always required a custom driver in the Chromium kernel.
>
> That's good to know. I guess there is nothing that prevents the final
> display of virtual GPUs from multiple guests being mapped onto the
> final presentation? The automotive use case seems to treat each
> individual VM with a UI as presenting a surface which the final console
> manager composites up together depending on safety rules to display to
> the user.

Well, in the Wayland use case, AIUI virtio-gpu is just a transport for
the Wayland protocol + shared memory resources.  The simplest case is
just sending shared CPU memory buffers around (wl_shm), so there's not
really any GPU involved in anything but name.  Alternatively, it's
possible to use dma-bufs, and graphics acceleration through the
virtio-gpu devices, and yes, when doing that it's still possible for the
host Wayland compositor to combine everything into one presentation — I
think they're all just dma-bufs to it.

Does that make sense?  I'm also no expert on this but hopefully I'm not
too far off.

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