RustyKext

A currently very minimal OS X kernel extension written partly in the Rust programming language.

• Writes "hello from rust" to the kernel log when the kext is loaded. That's it.
• Xcode project assumes that rustc is installed at /usr/local/bin/rustc.
• Uses a variety of features marked as "unstable", so you need a nightly build. Relying on unstable features means this may no longer compile with the latest nightly. I promise it did work with the x86-64 OSX build from 1st August 2015.
• This currently depends on the "core" library, but it doesn't actually link against it, it only uses some inline functions. I don't know if that's a good idea in the long term.
• I use the following command line arguments for rustc:
  • --emit obj - generate .o files, to be linked by Apple's own clang linker.
  • --crate-type staticlib - Not sure if this is actually needed.
  • -C soft-float - emulate floating-point code and don't use float registers for arguments. Kexts written in C or C++ likewise use -msoft-float with clang to avoid accidentally using floats in the kernel. (It's not disallowed, but doing so has implications.)
  • -C no-redzone=y - This is super important: don't use the x86-64 red zone, as interrupt handlers will trample over it.
  • -C no-stack-check - Otherwise ___morestack is an undefined symbol, which we can't really do anything about in the kernel.
• The panic etc. language features aren't properly wired up yet.
• Still uses the wrapper RustyKext.c, although I could get rid of that if I knew how to call variadic C functions from Rust.

I wrote a thing on this back in the Rust 0.9 days. Things have changed quite a bit in Rust-land since then, so it's probably not much use.