Using Rust with Buildroot (pre-built binaries)
Rust is a modern, compiled, programming language, oriented towards safety, memory control and concurrency. Its performances are comparable to C++.
Rust's features make it a good candidate for writing programs for embedded systems.
In this article, we will build a system for QEMU ARM Vexpress using Buildroot, then add support for Rust by installing the pre-built toolchain in the Buildroot environment. Finally, we will write a test program in Rust, compile it and run it from the generated system.
Build System Image
First, grab the Buildroot source code and initialize the configuration:
# Clone Buildroot repository git clone https://git.buildroot.net/buildroot cd buildroot # Configure for the desired system make O=$HOME/build/demo-rust/qemu/arm qemu_arm_vexpress_defconfig
Then, edit the configuration:
Go to the "Toolchain" menu and select "glibc" instead of "uclibc" as the targeted C library. Also select support for C++. Save your configuration and exit, then start the build:
Install Pre-built Rust Toolchain
Download the binary versions of the Rust compiler for the host machine (x86_64 PC) and the standard library compiled for the target "arm-unknown-linux-gnueabihf" (compatible with the ARM Vexpress machine):
push dl wget https://static.rust-lang.org/dist/rust-1.7.0-x86_64-unknown-linux-gnu.tar.gz wget https://static.rust-lang.org/dist/rust-std-1.7.0-arm-unknown-linux-gnueabihf.tar.gz popd
Prepare for installation:
# Extract compiler binaries mkdir -p $HOME/build/demo-rust/qemu/arm/build/host-rust-1.7.0 tar -xzf dl/rust-1.7.0-x86_64-unknown-linux-gnu.tar.gz \ -C $HOME/build/demo-rust/qemu/arm/build/host-rust-1.7.0 \ --strip-components=1 # Extract ARM version of standard libary binaries mkdir -p $HOME/build/demo-rust/qemu/arm/build/host-rust-std-1.7.0 tar -xzf dl/rust-std-1.7.0-arm-unknown-linux-gnueabihf.tar.gz \ -C $HOME/build/demo-rust/qemu/arm/build/host-rust-std-1.7.0 \ --strip-components=1
Next, install the compiler:
pushd $HOME/build/demo-rust/qemu/arm/build/host-rust-1.7.0 ./install.sh --prefix=$HOME/build/demo-rust/qemu/arm/host/usr \ --disable-ldconfig popd
Finally, install the cross-compiled standard library:
Build Test Program
Now is the time to test the compiler. Create the Rust source file for the "Hello World" program:
mkdir -p $HOME/src/hello-rust cat <<EOF > $HOME/src/hello-rust/main.rs fn main() { println!("Hello World!"); } EOF
To build the hello-rust test program, execute:
export PATH=$HOME/build/demo-rust/qemu/arm/host/usr/bin:$PATH $HOME/build/demo-rust/qemu/arm/host/usr/bin/rustc \ --target=arm-unknown-linux-gnueabihf \ -C linker=arm-buildroot-linux-gnueabihf-gcc \ -o $HOME/build/demo-rust/qemu/arm/target/usr/bin/hello-rust \ $HOME/src/hello-rust/main.rs
Note that the triplet used with the --target option is the same of the one from the downloaded standard library, which is different from the one for the linker to use.
Run Test Program from System
Rebuild the system image:
Now, you can start your system using QEMU:
qemu-system-arm \ -M vexpress-a9 \ -m 256 \ -kernel $HOME/build/demo-rust/qemu/arm/images/zImage \ -dtb $HOME/build/demo-rust/qemu/arm/images/vexpress-v2p-ca9.dtb \ -drive file=$HOME/build/demo-rust/qemu/arm/images/rootfs.ext2,if=sd,format=raw \ -append "console=ttyAMA0,115200 root=/dev/mmcblk0" \ -serial stdio \ -net nic,model=lan9118 \ -net user
Log as "root" (no password) and execute the test program:
Congratulations! You've run your first Rust program on an (emulated) embedded Linux system. Feel free to adapt the example to run the program on a real ARM system, such as Raspberry Pi.