[PATCH 13/15] drm/amdgpu: adapt vm size for multi vmpt

[Zhang, Jerry (Junwei)]

On 03/27/2017 01:53 PM, Chunming Zhou wrote:
> Change-Id: I17b40aec68404e46961a9fda22dfadd1ae9d6f2c
> Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> index 6625a2f..613c8f6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> @@ -508,6 +508,12 @@ static int gmc_v9_0_vm_init(struct amdgpu_device *adev)
>   	 * amdkfd will use VMIDs 8-15
>   	 */
>   	adev->vm_manager.num_ids = AMDGPU_NUM_OF_VMIDS;
> +	/* Because of four level VMPTs, vm size at least is 256GB.
> +	256TB is OK as well */

If each PT size is 9, and contains 3 levels PT + 1 PD.
9 * 3 + 12(page size) + 1(at least 1 bit for PD) = 40 bits here.

Then it looks 1T is minimum size.
Please confirm it.

Jerry.

> +	if (amdgpu_vm_size < 256) {
> +		DRM_WARN("vm size at least is 256GB!\n");
> +		amdgpu_vm_size = 256;
> +	}
>   	adev->vm_manager.num_level = 1;
>   	amdgpu_vm_manager_init(adev);
>
>