If you looks at the history then you will see that many different solutions have been proposed but Christoph's responses essentially boil down to 'do it somewhere else' and 'no not there', until it is basically 'not at all'. He is not in a position to make this decision, only Linus is. The patch as it stands lives outside of any sub-systems within Christoph's purview, he is simply being obstructionist out of tribalism.
> he is simply being obstructionist out of tribalism.
What about the part quoted in GPs comment?
> > The only reason Linux managed to survive so long is by not having internal boundaries, and adding another language complely breaks this
Wouldn't adding another language add an internal boundary? I don't know enough the kernel or kernel development to say it's an good argument or not, but it doesn't seem to be tribalism. I do know Rust already seems to be in some/few places in the kernel, but adding more would add more internal boundaries, as it'll get more and more divided. But again, maybe I don't understand clearly.
I agree that it may not be tribalistic, it's very possible that the maintainer has a valid technical/social opinion on this.
However, I don't think it is in any way acceptable to insert this in discussions about a random Rust patch. It's disrespectful to the time and expertise of the people who submitted these patches to first nitpick various technical items, only to later make it clear you were never going to accept their patch in the first place, because you dislike and oppose the decision that you know has already been made, to allow Rust in the kernel.
If he instead was (1) upfront about the fact that he would never allow Rust code in the subcomponent he maintains, and (2) stepped out of the discussion of this patch once it was moved out of said component, and then (3) started a completely separate thread on changing the kernel's stance on Rust to block all future patches and consider removing it entirely, that would all have been normal respectable behavior.
Although it was a DMA patch, it was not in the DMA subsystem that Christoph maintains. More specifically, it was not a file in the kernel/dma directory, but rather a file in the rust/kernel directory, which is where the Rust subsystem lives.
The Rust code is essentially a consumer of the DMA public API, much like many other subsystems in the kernel that consume it.
This is why some people are upset and confused about the situation; he added a Nacked-by tag to a patch that is outside his area. He had good reasons for it, but it was hard to see them based on the way he wrote his replies.
