Why Rust? Doesn't Microsoft have their own similar language, C#? And then isn't there some lore about the reason Windows Vista took so long to release was due to them trying to write the entire OS in C# or something and then having to redo everything?

C# isn't even remotely similar. A managed language running in a heavy VM runtime versus a direct-to-machine-code compiled language...

Have you heard of native AOT compilation?

1. That still needs a GC, and thus heap space. Unless you make everything stackalloc which is impossible in kernel programming

2. It is heavily pinned by unnecessary metadata. Well, actually some maybe necesdary to facilitate GC but it is bloated anyway

3. RyuJIT is not as optimized as LLVM, and RyuJIT produced the AOT code. There in an abandoned project called LILAC attemping to use LLVM as a second AOT generator but it was never heard from again after 2019.

4. Native interoperability in .net requires JIT as well, to generate things like call sites and runtime thunks (function pointers to restore CLR context). Not only that wastes more resources but also that not all P/Invoke calls can be AOT compiled.

1. Well technically speaking, you need a unified heap space. Just like in Linux kernel you have vmalloc and kmalloc which does virtual memory and real, page-aligned physical memory. So this is technically means I will have to pre-allocate everything. But it is not gonna work, how do you save space?

2. "necessary". I should have enabled autocorrect on my phone, it does more good than harm this time if I had it on.

3. It's actually LLILC (https://github.com/dotnet/llilc). I just remembered how to pronounce it. But if the name is wrong, then you have to correct it.