Nouveau - Aug 2019 - [PATCH 15/15] amdgpu: remove CONFIG_DRM_AMDGPU_USERPTR

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 at lst.de>
> ---
>  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.

Reviewed-by: Jason Gunthorpe <jgg at mellanox.com>

Jason

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 at lst.de>
>> ---
>>   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.

Regards,
   Felix
>
> Reviewed-by: Jason Gunthorpe <jgg at mellanox.com>
>
> Jason

On Tue, Aug 6, 2019 at 1:51 PM Kuehling, Felix <Felix.Kuehling at amd.com>
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 at lst.de>
> >> ---
> >>   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 at mellanox.com>
> >
> > Jason
> _______________________________________________
> amd-gfx mailing list
> amd-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx