Free user space for non-graphics drivers

The main use-case is to run the nvidia blob for CUDA and that stuff. And to run that they dig a direct path from the windows kernel gpu driver to linux, but the code that runs in linux isn't a linux driver at all, it's a windows driver. Simply recompiled so it's an ELF .so instead of PE .dll.

Even the mesa gl driver that could run on top of this is the brand new windows gl mesa driver that runs on top of directx. So really this is all about running the windows graphics stack, in linux, on top of windows. It'll never run on bare metal, and it won't look like a linux graphics stack. Hence why the wayland compositor is completely custom, and will use RDP to shovel the buffers over the wire to windows. Essentially microsoft is working on a wayland compositor for windows, using the windows directX stack and windows paravirt RDP desktop integration stuff, but then accidentally run that on linux. But still a windows graphics stack (just now also with wayland protocol support) end to end.

Whether drivers/hyperv wants that or not in upstream is entirely different question.