@feld @TTimo @sendpaws Regarding DirectX and Windows/Xbox, there are multiple abstractions at play. There's the DirectX API with a library, there's the userspace driver that handles the DirectX calls made from the Windows runtime and translates them into something the NT GPU driver can understand and then there's kernel driver which finally talks to the GPU. That's how this works on PCs and I doubt that Microsoft reengineered this whole behemoth specifically for Xbox since they use the same kernel since Windows 10.

Incidentally that's how Intel was able to emulate Dx9 on the first gen Arc GPUs. The userspace driver advertised Dx9 support and emulated it completely in software. The kernel driver had no idea what Dx9 was.

For Playstation 4, I remember reading a post or maybe watching a video about how the games have more-or-less direct access to GPU memory, but I'm also likely misremembering that since that was years ago when the first PS4 jailbreaks popped up.

https://www.youtube.com/watch?v=Qp3BGu3vixk