README.md

min-gba

A minimal setup to build Rust into a GBA ROM.

This crate is not for general use!

If you'd like to program a GBA game try the gba crate. The point of this repo is just to ensure that crater runs which break the thumbv4t-none-eabi target get caught.

What's Needed

• rustup default nightly (or run all commands with cargo +nightly)
• rustup component add rust-src
• arm-none-eabi binutils (either via The ARM Website, or your linux package manager).
• The following files:
  • .cargo/config.toml
  • src/rsrt0.S
  • linker_script.ld
  • build.rs

Rust Analyzer

It'll go nuts, here's how you fix it:

.vscode/settings.json:

{
  "rust-analyzer.checkOnSave.allTargets": false,
  "rust-analyzer.checkOnSave.extraArgs": [
    "--lib"
  ]
}

Final ROM

What you get with the project setup is an executable ELF file, but mgba can run it directly, so that's fine.

For a finalized ROM there's some post-processing steps:

• objcopy must be used to extact just the binary guts from the ELF file.

  • The command you want is probably something like this (change main to your binary's own name):
  • arm-none-eabi-objcopy -O binary target/thumbv4t-none-eabi/release/main target/main.gba

• gbafix should be used to apply the correct header.

  • You can get a Rust version of gbafix via cargo: cargo install gbafix
  • You can also get the C version of gbafix from the DevKitPro folks.
  • Either way, gbafix main.gba will ensure that the gba file has the correct header info.