Cross compile rust-openssl for Raspberry Pi 2

Question

I am on a Debian machine and I want to cross compile a project for my Raspberry Pi 2. I\'ve managed to do it for a simple hello world using rustup, but couldn\'t figure out how

Answer 1

You must pass shared option when configuring openssl compilation (this will make -fPIC parameter be passed to the compiler).

Here is a sequence of commands that I used to test cross compiling a Rust program that prints the openssl version:

cd /tmp

wget https://www.openssl.org/source/openssl-1.0.1t.tar.gz
tar xzf openssl-1.0.1t.tar.gz
export MACHINE=armv7
export ARCH=arm
export CC=arm-linux-gnueabihf-gcc
cd openssl-1.0.1t && ./config shared && make && cd -

export OPENSSL_LIB_DIR=/tmp/openssl-1.0.1t/
export OPENSSL_INCLUDE_DIR=/tmp/openssl-1.0.1t/include
cargo new xx --bin
cd xx
mkdir .cargo
cat > .cargo/config << EOF
[target.armv7-unknown-linux-gnueabihf]
linker = "arm-linux-gnueabihf-gcc"
EOF

cat > src/main.rs << EOF
extern crate openssl;

fn main() {
    println!("{}", openssl::version::version())
}
EOF

cargo add openssl # requires cargo install cargo-add
cargo build --target armv7-unknown-linux-gnueabihf

Testing the compiled program on the host computer

Setting OPENSSL_STATIC makes rust-openssl be statically linked. If you use the static linked version of rust-openssl, install a libc for armhf (crossbuild-essential-armhf on Debian) and qemu-static, you can the run the compiled program with the command:

qemu-arm-static target/armv7-unknown-linux-gnueabihf/debug/xx