On 2018-03-23 03:35 PM, Christian König wrote: > Am 23.03.2018 um 20:30 schrieb Felix Kuehling: >> On large-BAR systems the VM page tables for compute are accessed by >> the CPU. Always allow CPU access to the page directory so that it can >> be used later by the CPU when a VM is converted to a compute VM. > > NAK, that means we initial place the PD in the visible are for GFX > which is not desired (not much of an issue for Vega/Raven, but bad for > older generations). I'm not setting AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED. Doesn't that mean the buffer can be placed in invisible VRAM initially? > > Better to clear the flag later on and set the > AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED and then re-validate. The AMDGPU_GEM_CREATE_NO_CPU_ACCESS seems to mean "this BO must never be CPU mapped". Clearing that flag later kind of defeats the purpose of making such a declaration at allocation time. If I know that the buffer may need CPU access at some point in the future, I figured I shouldn't set the flag in the first place. FWIW, I didn't see any example of the AMDGPU_GEM_CREATE_NO_CPU_ACCESS flag ever being removed from an existing BO. Regards,  Felix > > Regards, > Christian. > >> >> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com> >> --- >>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 3 +-- >>  1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c >> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c >> index 90ff79e..bc3557b 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c >> @@ -2406,8 +2406,7 @@ int amdgpu_vm_init(struct amdgpu_device *adev, >> struct amdgpu_vm *vm, >>      if (vm->use_cpu_for_update) >>          flags |= AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED; >>      else >> -       flags |= (AMDGPU_GEM_CREATE_NO_CPU_ACCESS | >> -               AMDGPU_GEM_CREATE_SHADOW); >> +       flags |= AMDGPU_GEM_CREATE_SHADOW; >>       size = amdgpu_vm_bo_size(adev, adev->vm_manager.root_level); >>      r = amdgpu_bo_create(adev, size, align, true, >> AMDGPU_GEM_DOMAIN_VRAM, >
