Hi, On Mon, 17 May 2021 at 20:12, Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > Am 17.05.21 um 09:40 schrieb Daniel Vetter: > > We have, it's called drivers/gpu. Feel free to rename to drivers/xpu or > > think G as in General, not Graphisc. > > I hope this was a joke. > > Just some thoughts: > > AFAICT AI first came as an application of GPUs, but has now > evolved/specialized into something of its own. I can imagine sharing > some code among the various subsystems, say GEM/TTM internals for memory > management. Besides that there's probably little that can be shared in > the userspace interfaces. A GPU is device that puts an image onto the > screen and an AI accelerator isn't. But it isn't. A GPU is a device that has a kernel-arbitrated MMU hosting kernel-managed buffers, executes user-supplied compiled programs with reference to those buffers and other jobs, and informs the kernel about progress. KMS lies under the same third-level directory, but even when GPU and display are on the same die, they're totally different IP blocks developed on different schedules which are just periodically glued together. > Treating both as the same, even if > they share similar chip architectures, seems like a stretch. They might > evolve in different directions and fit less and less under the same > umbrella. Why not? All we have in common in GPU land right now is MMU + buffer references + job scheduling + synchronisation. None of this has common top-level API, or even a common top-level model. It's not just ISA differences, but we have very old-school devices where the kernel needs to register fill on every job, living next to middle-age devices where the kernel and userspace co-operate to fill a ring buffer, living next to modern devices where userspace does some stuff and then the hardware makes it happen with the bare minimum of kernel awareness. Honestly I think there's more difference between lima and amdgpu then there is between amdgpu and current NN/ML devices. Cheers, Daniel
