> Although I think I recall that the kernel doesn't use Rust's standard library Rust's standard library has three elements core has stuff you get with the Rus

> Although I think I recall that the kernel doesn't use Rust's standard library Rust's standard library has three elements core has stuff you get with the Rust language, like any use of Rust, Rust for Linux has core. You could technically implement Rust without core, or at least, without most of it, but that's not really the Rust language, you've instead made your own weird fork. [T]::sort_unstable() is a core function which sorts a slice of some Ordered type T but may re-arrange elements despite them comparing equal hence the word "unstable". alloc depends on an allocator. You may not have an allocator, e.g. you're a tiny embedded controller, in which case you likely don't want and can't use this. Rust for Linux re-implements alloc, basically cloning the "official" alloc and fiddling with it. Vec::try_reserve() is a feature found in alloc, it tries to allocate enough space to ensure your Vec has a certain amount of capacity beyond its current size, and if not reports it could not. std further depends on an Operating System, it offers exciting features like knowing what the time is, reading a file, connecting to a remote service over TCP/IP, or making a thread. Rust for Linux does not provide std. File::create() is a std function which creates files. The function you were interested in is part of core (although you were looking at its re-export from std) and so yes, it exists in Rust for Linux.