In a message to the Linux kernel mailing list, Hellwig wrote: "No Rust code in kernel/dma, please." For what it's worth, the patch added code to the rust/kernel portion of the Linux source tree, not kernel/dma, as far as we can tell.

All they were doing is adding an abstraction layer, within the already existing Rust code, so that rust drivers could communicate with the C DMA code in a uniform and predictable manner. It would have put far more work on maintainers, both C and Rust alike, to have each and every driver implement its own abstraction to the DMA API. Issues would have been/will be filed against the kernel/dma subtree in error due to issues with these myriad abstraction layers.

[–] Gayhitler@lemmy.ml 5 points 1 day ago

It’s a duplication of functionality in kernel/dma.

That’s why the submitter didn’t say “I didn’t submit to kernel/dma, checkmate libs!”.

The intent is to duplicate functionality in kernel/dma then get it included directly or linked to.

That’s what the r4l project is trying to do explicitly!

Before you say that kernel/dma didn’t have functional easy to use rust bindings, so the commit couldn’t have duplicated functionality: someone on kernel/dma said they didn’t want that and suggested using the c bindings instead which is what every other language has to do. Which means there was already a solution that was functional.

It’s like if there’s a community bicycle and you bring your drill and tap set so you can mount your bottle caddy and the community says “please don’t make a hole we have to tig in. Just use a pipe strap.” The right answer isn’t to start building a whole new down tube you can tap for an m5 for your bottle caddy, it’s to just use a pipe strap for your bottle caddy.

I didn’t read the linked article (or any linked article about this) because I’ve been reading the mailing list. Reporting on the kernel and people’s behavior on the list is tiring and often includes a bunch of baseless speculation.