Re: [PATCH v2 2/3] rust: dma: rename dma_handle to dma_address

[Danilo Krummrich]

On Wed Aug 5, 2026 at 1:32 PM CEST, Robin Murphy wrote:
> To be fair, that is sort of the intent in the C API as well, to be clear 
> that DMA addresses must not simply be treated as physical addresses, and 
> aren't necessarily address-like in general e.g. comparing two 
> dma_handles is pretty meaningless, since they could have different 
> values but still refer to the same underlying memory, or vice-versa. 
> Adding or subtracting offsets within the bounds of the original 
> allocation/mapping size is pretty much the only arithmetic that _is_ valid.

Yes, I did suggest a dma::Range type [1] for this purpose, such that only this
kind arithmetic is possible to do.

The dma::Range type should have a method returning its embedded raw value which
then can be used to program registers etc.

This patch is only an intermediate step, that clarifies that intent of the
current usage of dma_handle() (or now dma_address()), which is not to serve as a
handle.

[1] https://github.com/Rust-for-Linux/linux/issues/1248

> However at the Rust level, the abstraction itself can convey (and even 
> enforce!) most of that, so for the sake of clarity here, particularly if 
> Rust programmers are likely to have their own expectations of what 
> "address" and "handle" mean, then I'm inclined to agree.

Yeah, as mentioned in the link below, the handle that represents the allocation
are the DMA container types (such as dma::Coherent) themselves.

>> Link: https://lore.kernel.org/all/DK75LUA4NLGI.3P29AIZQE20V2@xxxxxxxxxx/