No, you can use Rust without its stdlib. #![no_std] is a crate-level attribute that indicates that the crate will link to the core-crate instead of the std-cra

No, you can use Rust without its stdlib. #![no_std] is a crate-level attribute that indicates that the crate will link to the core-crate instead of the std-crate. The libcore crate in turn is a platform-agnostic subset of the std crate which makes no assumptions about the system the program will run on. As such, it provides APIs for language primitives like floats, strings and slices, as well as APIs that expose processor features like atomic operations and SIMD instructions. However it lacks APIs for anything that involves platform integration. Because of these properties no_std and libcore code can be used for any kind of bootstrapping (stage 0) code like bootloaders, firmware or kernels. https://rust-embedded.github.io/book/intro/no-std.html https://rust-embedded.github.io/book/intro/no-std.html