For fun, I decided to take a look at a random syscall: fork.

* https://github.com/yuan-xy/Linux-0.11/blob/master/kernel/for...

* https://github.com/Poseidon-fan/linux-0.11-rs/blob/420152fdf...

The Rust is slightly shorter, though it also isn't organized in exactly the same way. The code isn't that different overall, creating and copying some data structures around, as you'd expect for a fork implementation of this vintage.

Maybe I got lucky, but I would expect that it's more of what other people said: this repository includes far more than the kernel.