Compiling Rust Projects for Milk-V Duo

This guide provides instructions on how to compile Rust projects for the Milk-V Duo, a device using the RISC-V architecture.

This is inspired from reading https://barretts.club/posts/i-got-a-milkv-duo/.

Prerequisites for building with Docker

• Docker installed

Docker Instructions

Using the Prebuilt Docker Image

This is the easiest way to build as you can support all operating systems that have a docker installation and using x86_64 or aarch64 processors.

1. Build Debug Version:

   docker run --rm -e LOCAL_UID=$(id -u) -e LOCAL_GID=$(id -g) -v $PWD:/app ejortega/duo-rust cargo +nightly build --target riscv64gc-unknown-linux-musl -Zbuild-std

   or use the provided python script

   ./build.py

2. Build Release Version:

   docker run --rm -e LOCAL_UID=$(id -u) -e LOCAL_GID=$(id -g) -v $PWD:/app ejortega/duo-rust cargo +nightly build --target riscv64gc-unknown-linux-musl -Zbuild-std --release

   or

   ./build.py --release
   

Build and Run Your Own Image

1. Build the Docker Image: Replace <tag> with your preferred tag name.

   docker build -t <tag> .

2. Compile Your Application: Use the following command to compile your app. Replace <tag> with the tag used above.

   docker run --rm -e LOCAL_UID=$(id -u) -e LOCAL_GID=$(id -g) -v $PWD:/app <tag> cargo +nightly build --target riscv64gc-unknown-linux-musl -Zbuild-std --release

Prerequisites without using Docker

• Linux operating system (x86_64 or aarch64)
• Rust programming environment

Setup Instructions

1. Add RISC-V Target in Rust: Run the following command to add the riscv64gc-unknown-linux-gnu target.

   rustup +nightly target add riscv64gc-unknown-linux-gnu

2. Download and Extract Toolchain:

   • I've provided compiled toolchains for x86_64 and aarch64. Download the appropriate RISC-V toolchain from this link.

   • Extract it in your project directory:

     tar xvf toolchain-riscv64-unknown-linux-musl-amd64.tar.xz 

     or (depending on arch)

     tar xvf toolchain-riscv64-unknown-linux-musl-arm64.tar.xz 

   • Update .config/config.toml in your project if you use a different toolchain version or to update the linker and sysroot paths.

3. Compile:

   First make sure you the update the linker and sysroot paths in the .config/cargo.toml.

   • Compile Debug

   cargo +nightly build --target riscv64gc-unknown-linux-musl -Zbuild-std

   • Compile Release

   cargo +nightly build --target riscv64gc-unknown-linux-musl -Zbuild-std --release

Troubleshooting

This should no longer be an issue after adding "-C", "link-arg=-Wl,--dynamic-linker=/lib/ld-musl-riscv64v0p7_xthead.so.1" to the config.toml but I'll leave for reference.

If you have trouble running the binary on the milk-v duo, the article mentions you can get by using:

ln -sf /lib/ld-musl-riscv64v0p7_xthead.so.1 /lib/ld-musl-riscv64.so.1

However, I would still get an error:

[root@milkv-duo]~# ./hello-world 
Error relocating ./hello-world: pthread_getname_np: symbol not found
Error relocating ./hello-world: pthread_getname_np: symbol not found

I was able to get away with copying libc.so from the toolchain onto the milk-v duo.

scp ./riscv64-lp64d--musl--bleeding-edge-2023.11-1/riscv64-buildroot-linux-musl/sysroot/lib/libc.so [email protected]:/lib/ld-musl-riscv64.so.1

[root@milkv-duo]~# ./hello-world 
Hello, world!
1970-01-01T00:47:05.638969Z  INFO milkv_duo_rust: Rust is the future