VirtIO Video Driver Coming Together For The Mainline Linux Kernel

[pal666]

That's nice, but it makes me wonder how hard can it be to write a VirtIO-Vulkan driver and have Vulkan compatible Windows games happily run in a Windows guest, at least for those hosts that have Vulkan compatible hardware and driver.

virtio are hardware drivers. vulkan is not hardware, though there can be hardware which can expose vulkan api. the happiest way to run windows games is proton

[lucrus]

virtio are hardware drivers. vulkan is not hardware, though there can be hardware which can expose vulkan api. the happiest way to run windows games is proton

VirtIO is software by definition. Whether it's emulating hardware (like a GPU) or other software (like a 1:1 mapping to the host Vulkan library) is irrelevant to the guest, as long as the guest only uses the exposed API (Vulkan in this case) and not some undocumented hardware feature directly.

I think the real problem is what oiaohm explained in comment #10.

[pal666]

VirtIO is software by definition.

it's driver for (virtual) hardware. while vulkan is userspace library

Whether it's emulating hardware (like a GPU) or other software (like a 1:1 mapping to the host Vulkan library)

you don't need drivers to emulate libraries. you need drivers to emulate hardware. i.e. what virtio can expose is "videocard", on top of which you can build vulkan driver

I think the real problem is what oiaohm explained in comment #10.

his comment (and linked blog post) discusses improvements to hardware driver virtio-gpu which allow building vulkan drivers for such hardware. right now its features support only opengl driver(just like not every physical gpu can support vulkan)

[lucrus]

it's driver for (virtual) hardware. while vulkan is userspace library
you don't need drivers to emulate libraries. you need drivers to emulate hardware.

I get your point, but you can always emulate a fake hardware that happens to offer, in kernel space, just the same virtualized hardware calls as a userspace Vulkan library. Then you only need a thin Vulkan userspace wrapper library around that driver (virtualized hardware) if the problem is having Vulkan userspace API bindings.

Anyway all that is just my fantasy, because, as oiaohm explained, API bindings are not enough: you also need memory buffers and those pose a greater problem.

i.e. what virtio can expose is "videocard", on top of which you can build vulkan driver

Yes, before oiaohm answer, I used to imagine it exposing a "Vulkan only videocard". I know, it does not necessarily make sense, it was just a trial at solving a problem I don't deeply understand.