[Ygg2]

Even if you put that aside, the problem is you offer Hellwig two solutions and he NACKs them both.

  H: I don't want to support multilanguage codebase
  R: We'll have a maintainer verify R4L is behaving properly.
  H: I solved issues because they were unified.
  R: Rust will be mirror of whatever C is, and you're free to break it, R4L will maintain it.
  H: No.

[DSMan195276]

I'll bite and play devils advocate here - both of those are not a solution to his problem. Ultimately he's the maintainer and he gets the emails if X driver is broken, so because of that he doesn't want to rely on another group to maintain the 'Rust half' of his part of the code. It's also a system that works until it doesn't, the biggest rule of the kernel is no breaking userspace - at some point in the future it won't matter if it's his C changes breaking the Rust drivers, it's still his changes that have to be rolled back if the Rust code isn't updated.

And to clarify I'm not saying he's right or wrong or acting good or bad. I have however expected R4L to ultimately fall apart because of this exact issue, the maintainers have never been on board with maintaining Rust code and that hasn't changed. While that remains the case the project is going to be stuck at a wall - to the point that if they're confident they can maintain the Rust code themselves they should just fork it and do that. If it works well enough they'll eventually be too popular to ignore with people choosing to write their new modules in Rust instead.

[dralley]

That is not a problem. Christoph does not have the right to gatekeep who can use DMA. If he tried to veto an Nvidia graphics driver from using DMA using the excuse that "it might create more work for me", everyone would rightfully tell him to f-off, because that's not his call.