On Sun, Dec 13, 2020 at 04:09:25PM +0100, Thomas Hellström (Intel) wrote: > > On 12/11/20 1:46 PM, Jason Gunthorpe wrote: > > On Fri, Dec 11, 2020 at 08:50:53AM +0100, Thomas Hellström (Intel) wrote: > > > > > My understanding of this particular case is that hardware would continue to > > > DMA to orphaned pages that are pinned until the driver is done with > > > DMA, > > mmu notifier replaces pinning as the locking mechanism. Drivers using > > mmu notifier should not be taking pins. > > > > Keep in mind this was all built for HW with real shadow page tables > > that can do fine grained manipulation. > OK yes, that makes sense and in that context the fence wait is easier to > understand. Looks like for example the radeon driver is using the notifier + > get_user_pages() but there it looks like it's used to avoid having > get_user_pages() clash with invalidation. I think the radeon userptr implementation is bad enough that Christian wants to outright remove it. At least he keeps talking about doing that. So maybe not a good example to look at :-) -Daniel > > The GPU version of this to instead manipulate a command queue is a big > > aberration from what was intended. > > > > Jason > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
