On Wed, Apr 28, 2021 at 11:07:09AM +0200, Michel Dänzer wrote: > On 2021-04-28 8:59 a.m., Christian König wrote: > > Hi Dave, > > > > Am 27.04.21 um 21:23 schrieb Marek Olšák: > >> Supporting interop with any device is always possible. It depends on which > >> drivers we need to interoperate with and update them. We've already found > >> the path forward for amdgpu. We just need to find out how many other > >> drivers need to be updated and evaluate the cost/benefit aspect. > >> > >> Marek > >> > >> On Tue, Apr 27, 2021 at 2:38 PM Dave Airlie <airl...@gmail.com > >> <mailto:airl...@gmail.com>> wrote: > >> > >> On Tue, 27 Apr 2021 at 22:06, Christian König > >> <ckoenig.leichtzumer...@gmail.com > >> <mailto:ckoenig.leichtzumer...@gmail.com>> wrote: > >> > > >> > Correct, we wouldn't have synchronization between device with and > >> without user queues any more. > >> > > >> > That could only be a problem for A+I Laptops. > >> > >> Since I think you mentioned you'd only be enabling this on newer > >> chipsets, won't it be a problem for A+A where one A is a generation > >> behind the other? > >> > > > > Crap, that is a good point as well. > > > >> > >> I'm not really liking where this is going btw, seems like a ill > >> thought out concept, if AMD is really going down the road of designing > >> hw that is currently Linux incompatible, you are going to have to > >> accept a big part of the burden in bringing this support in to more > >> than just amd drivers for upcoming generations of gpu. > >> > > > > Well we don't really like that either, but we have no other option as far > > as I can see. > > I don't really understand what "future hw may remove support for kernel > queues" means exactly. While the per-context queues can be mapped to > userspace directly, they don't *have* to be, do they? I.e. the kernel > driver should be able to either intercept userspace access to the > queues, or in the worst case do it all itself, and provide the existing > synchronization semantics as needed? > > Surely there are resource limits for the per-context queues, so the > kernel driver needs to do some kind of virtualization / multi-plexing > anyway, or we'll get sad user faces when there's no queue available for > <current hot game>. > > I'm probably missing something though, awaiting enlightenment. :)
Yeah in all this discussion what's unclear to me is, is this a hard amdgpu requirement going forward, in which case you need a time machine and lots of people to retroactively fix this because this aint fast to get fixed. Or is this just musings for an ecosystem that better fits current&future hw, for which I think we all agree where the rough direction is? The former is quite a glorious situation, and I'm with Dave here that if your hw engineers really removed the bit to not map the ringbuffers to userspace, then amd gets to eat a big chunk of the cost here. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
