On 9/22/25 9:08 AM, Danilo Krummrich wrote:
> On 9/22/25 1:30 PM, Alistair Popple wrote:
>> + // SAFETY: No DMA allocations have been made yet
>
> It's not really about DMA allocations that have been made previously, there is
> no unsafe behavior in that.
>
> It's about the method must not be called concurrently with any DMA allocation
> or
> mapping primitives.
>
> Can you please adjust the comment correspondingly?
>
>> + unsafe { pdev.dma_set_mask_and_coherent(DmaMask::new::<47>())? };
>
> As Boqun mentioned, we shouldn't have a magic number for this. I don't know if
> it will change for future chips, but maybe we should move this to gpu::Spec to
It changes to 52 bits for GH100+ (Hopper/Blackwell+). When I post those
patches, I'll use a HAL to select the value.
> be safe.
>
> At least, create a constant for it (also in gpu::Spec?); in Nouveau I named
> this
> NOUVEAU_VA_SPACE_BITS back then. Not a great name, if you have a better idea,
> please go for it. :)
GPU_DMA_BIT_WIDTH, for now?
thanks,
--
John Hubbard
