So you’ve got a CHIP microcomputer, and you want to write some stuff in Rust for it. You can use Rust on the Chip itself because it can be used like a normal Linux computer, but it’s also possible to cross compile then run the binary on the Chip.

Here is a simple guide to doing that cross compilation from macOS. I suggest looking up more information on something if you aren’t sure what it’s doing.

The Chip runs Linux on an ARM processor. We’re going to first need a way to compile things for that platform. To do this we can leverage musl-cross-make as a way to do this.

The easiest way to install musl is using the homebrew-musl-cross formula (install Homebrew if you don’t already have it). There are a few options you can run the install with, so check out that link if you want to see them.

We need to install it using the --with-arm flag, and for our need now we don’t really care about the x86_64 stuff, so we can also use --without-x86_64. Overall the command we need to run is brew install FiloSottile/musl-cross/musl-cross --with-arm --without-x86_64.

This will probably take a while to build (it took me ~40 minutes).

When it’s done, we have a bunch of commands prefixed with arm-linux-muslabi-. For example arm-linux-muslabi-gcc now exists, and is basically gcc for arm-linux-muslabi machines (using the --static flag builds static binaries that can run on just arm-linux machines).

Now that we have a compiler, we can move onto Rust stuff.

Run cargo new hello_world --bin if you don’t already have a Rust project you want to build.

Using rustup we can add a target for ARM Linux architectures. Here’s the command to do so: rustup target add arm-unknown-linux-musleabi.

In your project edit .cargo/config (creating the directory or file if they don’t exist), adding the following

[target.arm-unknown-linux-musleabi]
linker = "arm-linux-musleabi-gcc"

This will make Cargo use our new gcc as a linker when we build for the target we specified (subbing for different targets/linkers allows you to build for things other than the Chip/ARM).

Now you can run cargo build --target=arm-unknown-linux-musleabi --release and hopefully successfully have built for ARM Linux.

By running file target/arm-unknown-linux-musleabi/release/hello_world I get the following output

target/arm-unknown-linux-musleabi/release/hello_world: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, not stripped

Now you can move the binary to the Chip however you like.

If you have your Chip connected to the same network, you can run scp target/arm-unknown-linux-musleabi/debug/hello_world chip@chip.local:/home/chip/hello_world to copy via terminal (default password is chip).

Tip: If you can plug/power your Chip via USB-2, you can run screen /dev/tty.usbmodem***** 115200 to connect to your Chip without having to plug it into a TV. Replace the asterisks with whatever numbers you get by running ls /dev/tty.usbmodem*.