Re: [PATCH v2] drm/ttm: Support 52-bit PAs in ttm_place

[Tvrtko Ursulin <tursulin@ursulin.net>]

On 13/05/2026 15:12, Felix Kuehling wrote:
> fpfn and lpfn in struct ttm_place are 32-bit page numbers. With 4KB page
> size this can support up to 44-bit physical addressing. Grow these to
> unsigned long to support larger physical addresses.
> 
> Signed-off-by: Felix Kuehling <felix.kuehling@amd.com>
> ---
>   include/drm/ttm/ttm_placement.h | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/drm/ttm/ttm_placement.h b/include/drm/ttm/ttm_placement.h
> index b510a4812609..ab2639e42c54 100644
> --- a/include/drm/ttm/ttm_placement.h
> +++ b/include/drm/ttm/ttm_placement.h
> @@ -81,8 +81,8 @@
>    * Structure indicating a possible place to put an object.
>    */
>   struct ttm_place {
> -	unsigned	fpfn;
> -	unsigned	lpfn;
> +	uint64_t	fpfn;
> +	uint64_t	lpfn;
>   	uint32_t	mem_type;
>   	uint32_t	flags;
>   };

Maybe audit of usage sites is required to make sure no compiler warnings 
on 32-bit builds if nothing else. Things like:

amdgpu_vram_mgr_intersects()
...
		if (place->fpfn < lpfn &&
		    (!place->lpfn || place->lpfn > fpfn))
			return true;

Etc. Probably are all best adjusted to match the new type.

There is also:

struct ttm_resource {
	unsigned long start;

Which also may need aligning. I know no one cares about 32-bit builds 
but some automated systems will probably test it and send reports.

Regards,

Tvrtko