Cargo is the official Rust package manager. It will fetch the dependencies of a Rust project and compile everything. Adding support for Cargo in Buildroot will allow the end user to to easily cross-compile programs for an embedded system.
We assume that a Buildroot-based environment as been set up as described previously.
Grab the source code of the latest version (0.9.0) and extract it.
git clone --recursive https://github.com/rust-lang/cargo \ -b 0.9.0 \ $HOME/build/demo-rust/qemu/arm/build/host-cargo-0.9.0
Cargo needs OpenSSL and CMake (and Python, but it is assumed that a Python interpreter is available on the build machine):
It also depends on the host version of libssh2, which is unfortunately not available in Buildroot. But it is easy to add it:
echo '$(eval $(host-autotools-package))' >> package/libssh2/libssh2.mk make O=$HOME/build/demo-rust/qemu/arm host-libssh2
Configure and build:
export PATH=$HOME/build/demo-rust/qemu/arm/host/usr/bin:$PATH export PKG_CONFIG=$HOME/build/demo-rust/qemu/arm/host/usr/bin/pkgconf export LIBRARY_PATH=$HOME/build/demo-rust/qemu/arm/host/usr/lib pushd $HOME/build/demo-rust/qemu/arm/build/host-cargo-0.9.0 ./configure --prefix=$HOME/build/demo-rust/qemu/arm/host/usr \ --localstatedir=$HOME/build/demo-rust/qemu/arm/host/var/lib \ --sysconfdir=$HOME/build/demo-rust/qemu/arm/host/etc make make install popd
Note that Cargo bootstrap itself, as seen in the build log:
Now is the time to test Cargo. Create a new crate for the "Hello World" program:
To allow cross-compilation of a crate, some parameters must be set in the Cargo configuration file. Create this file as follow:
mkdir .cargo cat <<EOF > .cargo/config [target.arm-buildroot-linux-gnueabihf] linker = "arm-buildroot-linux-gnueabihf-gcc" EOF
Here, Cargo is instructed to use the linker from the toolchain generated by Buildroot when the target is "arm-buildroot-linux-gnueabihf".
Tell the Rust compiler where the target specification can be found:
Now, build the crate:
Once the build is finished, check the result executable is for an ARM machine:
$ file -b target/arm-buildroot-linux-gnueabihf/release/hello-rust ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 4.5.0, not stripped
Finally, copy the result binary file in the target rootfs:
cp -a target/arm-buildroot-linux-gnueabihf/release/hello-rust \ $HOME/build/demo-rust/qemu/arm/target/usr/bin
For futher details on using Cargo and creating crates, please refer to the Cargo documentation.