Nothing at all, really, but kernel developers are going to be picky. For example, does LLVM target all of the architectures Linux supports today? Also, I think it's hard to sell Rust as a hard dependency of the Linux kernel when it isn't nearly as widespread as almost every other kernel dependency.
I also sorta remember some kernel developers (not necessarily Linux) making a fuss about rustc using a huge amount of address space and not working on 32-bit systems for that reason - although frankly, I can't remember where I read that and I'm starting to question how much I'm misremembering there.
> I also sorta remember some kernel developers (not necessarily Linux) making a fuss about rustc using a huge amount of address space and not working on 32-bit systems for that reason - although frankly, I can't remember where I read that and I'm starting to question how much I'm misremembering there.
Yep, that's exactly what I was remembering. Though I disagree that rewriting coreutils in Rust is a good place to start, there are definitely some valid points in there. I wonder if the i386 situation has been resolved at this point.
Well, if you want to be pedantic, there's already non-C code in the kernel, it just doesn't make it into the runtime. I've seen Linus's opinion on C++ in the kernel, but I've never seen anyone explicitly state that no other languages would be accepted. I'm sure that it's something that's always possible even if very unlikely right now.
Blanketing every architecture LLVM doesn't support that GCC does an "obscure hobby architecture" is not really a great way to look at things imo. I haven't looked into it but I'm pretty sure outside the bubble of desktop computers there are plenty of important uses of Linux on less common architectures, I would assume mostly embedded systems.
I also sorta remember some kernel developers (not necessarily Linux) making a fuss about rustc using a huge amount of address space and not working on 32-bit systems for that reason - although frankly, I can't remember where I read that and I'm starting to question how much I'm misremembering there.