Some Rust cross-compiling resources for Raspberry Pi

As I work on setting up a Pi Zero W as a portable system for some lightweight dev, I'm running into the challenge of compiling certain binaries on-system. To say that the Pi Zero W's resources are limited is an understatement; it can take days to compile something that might take minutes on a more robust system.

What I wanted was to cross-compile Microsoft Edit. I got it working by installing rust on my Raspberry Pi 400 with the 64-bit OS, then adding the appropriate target:

rustup target add arm-unknown-linux-gnueabihf

I also installed the right version of the GCC cross compiler toolchain. At first, I did this with apt, but that wasn't right: if I'm using 64-bit for the host, it's going to link a 64-bit version for the target.

Instead, I installed a GCC toolchain manually (see the link to ttapa's docker-arm-cross-toolchain below), then set up armv6-rpi-linux-gnueabihf-gcc as the linker for the arm-unknown-linux-gnueabihf target in ~/.cargo/config.toml. This set up worked and I was able to compile and run Microsoft edit on the Pi Zero W!

Some resources on Rust packaging and cross compiling

From the Rust Book

• https://rust-cli.github.io/book/tutorial/packaging.html - Packaging in Rust
• https://rust-lang.github.io/rustup/cross-compilation.html - Cross-compiling in Rust
• https://doc.rust-lang.org/nightly/rustc/platform-support.html - Platform support in Rust, i.e., Tier 1/2/3

Other tutorials and docs

• https://kerkour.com/rust-cross-compilation
• https://github.com/japaric/rust-cross - some notes on cross-compiling with Rust
• https://reemus.dev/tldr/rust-cross-compilation-github-actions

Compilers and tools

• https://github.com/tttapa/docker-arm-cross-toolchain
• https://github.com/abhiTronix/raspberry-pi-cross-compilers - a collection of cross-compilers meant to run from x86_64 Linux systems
• https://github.com/cross-rs/cross - cross-compilers + containers to reduce installed components and dependencies

Compiling Microsoft Edit for older (armv6) Raspberry Pi

As mentioned above, the whole reason I started down this road was to compile Microsoft Edit for use on armv6 Raspberry Pi. Here's a step by step on how I made that work.

Get the source

git clone https://github.com/microsoft/edit.git

Install a cross-compiler toolchain

mkdir ~/opt
wget https://github.com/tttapa/docker-arm-cross-toolchain/releases/latest/download/x-tools-aarch64-rpi3-linux -gnu-armv6-rpi-linux-gnueabihf-gcc12.tar.xz
tar xJf x-tools-aarch64-rpi3-linux-gnu-armv6-rpi-linux-gnueabihf-gcc12.tar.xz -C ~/opt

Point cargo to the toolchain

Edit ~/.cargo/config.toml and add this:

[target.arm-unknown-linux-gnueabihf]
linker = "/home/georgew/opt/x-tools/armv6-rpi-linux-gnueabihf/bin/armv6-rpi-linux-gnueabihf-gcc"

Do the build

From inside the edit directory:

rustup component add rust-src --toolchain nightly-aarch64-unknown-linux-gnu
cargo build --config .cargo/release-nightly.toml --release --target=arm-unknown-linux-gnueabihf

Install ICU to support find

sudo apt install libicu-dev