Combine no_std, panic_handler, _start, and a VGA write.
Multistep capstone (inspired by phil-opp's "A Freestanding Rust Binary" + "Minimal Rust Kernel"):
1. Mark the file with #![no_std] AND #![no_main].
2. Add a #[panic_handler] fn panic(_info: &core::panic::PanicInfo) -> ! { loop {} }.
3. Define #[no_mangle] pub extern "C" fn _start() -> ! { ... loop {} }.
4. Inside _start, write the byte b'O' to 0xb8000 using core::ptr::write_volatile inside an unsafe block.
This is the minimum Rust needed to boot on bare metal x86.Sign in to save your code and track progress across devices.
