On Tue, Aug 6, 2019 at 1:51 PM Kuehling, Felix <Felix.Kuehling@xxxxxxx> wrote: > > On 2019-08-06 13:44, Jason Gunthorpe wrote: > > On Tue, Aug 06, 2019 at 07:05:53PM +0300, Christoph Hellwig wrote: > >> The option is just used to select HMM mirror support and has a very > >> confusing help text. Just pull in the HMM mirror code by default > >> instead. > >> > >> Signed-off-by: Christoph Hellwig <hch@xxxxxx> > >> --- > >> drivers/gpu/drm/Kconfig | 2 ++ > >> drivers/gpu/drm/amd/amdgpu/Kconfig | 10 ---------- > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 6 ------ > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 12 ------------ > >> 4 files changed, 2 insertions(+), 28 deletions(-) > > Felix, was this an effort to avoid the arch restriction on hmm or > > something? Also can't see why this was like this. > > This option predates KFD's support of userptrs, which in turn predates > HMM. Radeon has the same kind of option, though it doesn't affect HMM in > that case. > > Alex, Christian, can you think of a good reason to maintain userptr > support as an option in amdgpu? I suspect it was originally meant as a > way to allow kernels with amdgpu without MMU notifiers. Now it would > allow a kernel with amdgpu without HMM or MMU notifiers. I don't know if > this is a useful thing to have. Right. There were people that didn't have MMU notifiers that wanted support for the GPU. For a lot of older APIs, a lack of userptr support was not a big deal (it just disabled some optimizations and API extensions), but as it becomes more relevant it may make sense to just make it a requirement. Alex > > Regards, > Felix > > > > > Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> > > > > Jason > _______________________________________________ > amd-gfx mailing list > amd-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/amd-gfx
