Re: [PATCH 0/9] rust: dma: add CoherentArray for compile-time sized allocations

["Danilo Krummrich" <dakr@kernel.org>]

(Cc: Lyude)

I assume something odd is going on with your mail client for people that have
been added to a thread later on?

On Sat Jan 31, 2026 at 2:16 PM CET, Alexandre Courbot wrote:
> On Sat Jan 31, 2026 at 9:27 PM JST, Danilo Krummrich wrote:
>> We've just generalized I/O to support arbitrary I/O backends (busses, backing
>> storage, etc.).
>>
>> With this we can wire up the I/O traits to DMA and generalize the dma_read() and
>> dma_write() macros accordingly. I.e. we can extend the I/O traits with
>> field_write() and field_read().
>
> With the caveat that the I/O traits for now only support accessing
> primitive types; is the plan to add a function to read any type
> implementing `FromBytes`?

That's exactly what I say above: generalize the dma_read!() and dma_write!()
macros by adding field_write() and field_read() to the I/O traits. :)

For reference, this is where I brought this up originally [1].

[1] https://lore.kernel.org/all/DFOP5BY09539.AFY5L5FV1HNV@kernel.org/

>> (Lyude is going to work on this as a more integrated alternative to iosys_map.
>> It would be good to align with her regarding this work.)
>
> Heads up, I am also doing some plumbing in `io.rs` related to the
> register macro. Maybe we should have a thread on Zulip to discuss what
> everyone is working on.

Done!

Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Generic.20I.2FO.20backends/with/571198078

>> This has the advantage that we don't have to duplicate all this infrastructure
>> for I/O memory, DMA, etc.
>>
>> I also think that CoherentSlice is too specific of a type. I'd rather have a
>> generic type, maybe UnsafeSlice or IoSlice, that just uses the I/O backend for
>> accesses.
>
> For me the main appeal of this patchset is that it provides a way to
> work infallibly with a single object or a fixed-size array. I hope
> that's something we can preserve.

Of course, the generic I/O backend infrastructure is based on the distinction
between compile-time and run-time.