My (minimally-informed) summary of the mailing list posts is that Hellwig thinks that the addition of Rust to the kernel is fundamentally bad because it [1]<p><i>> turns Linux into a project written in multiple languages with no clear guidelines what language is to be used for where.</i><p>And that<p><i>> Having worked on codebase like that they are my worst nightmare, because there is a constant churn of rewriting parts from language A to language B because of reason X and then back because of reason Z.</i><p>Torvalds' position is that Hellwig doesn't have to like Rust or accept it in his subsystem at this point, but he has does have to accept that it <i>will</i> be part of the kernel [2]:<p><i>> You can't have it both ways. You can't say "I want to have nothing to do with Rust", and then in the very next sentence say "And that means that the Rust code that I will ignore cannot use the C interfaces I maintain".</i><p>Hellwig appears unwilling to accept that.<p>I think this is a reasonable position on both sides. If Linus wants Rust in his kernel, that's his choice. Memory safe languages are pretty much motherhood and apple pie at this point, and Linus very probably realises that Linux has to adapt or stagnate. On the other hand, if Christoph doesn't want to continue in a role that he sees as becoming mostly churn and pain, it's hard to blame him.<p>[1] <a href="https://lore.kernel.org/rust-for-linux/Z7SwcnUzjZYfuJ4-@infradead.org/" rel="nofollow">https://lore.kernel.org/rust-for-linux/Z7SwcnUzjZYfuJ4-@infr...</a><p>[2] <a href="https://lore.kernel.org/rust-for-linux/CAHk-=wgLbz1Bm8QhmJ4dJGSmTuV5w_R0Gwvg5kHrYr4Ko9dUHQ@mail.gmail.com/" rel="nofollow">https://lore.kernel.org/rust-for-linux/CAHk-=wgLbz1Bm8QhmJ4d...</a>