CODEWITHSUNDEEP
windowsgccarmrustcross-compiling
Timmmm
Timmmm

Reputation: 97028

Cross-compiling Rust from Windows to ARM Linux

I'm using Windows 10. I would like to cross-compile a Rust program to run on armv7-unknown-linux-gnueabihf. (armv7-unknown-linux-muscl would also be acceptable but it doesn't seem to be available.)

Here are my steps:

  1. Install rustup
  2. rustup toolchain install stable-x86_64-pc-windows-gnu
  3. rustup toolchain default stable-x86_64-pc-windows-gnu
  4. rustup target add armv7-unknown-linux-gnueabihf

  5. Edit my ./cargo/config file to contain:

    [build]
target = "armv7-unknown-linux-gnueabihf"

  6. cargo build

This compiles everything fine, but when it comes to linking it gives this error:

error: could not exec the linker `cc`: The system cannot find the file specified. (os error 2)

As far as I have been able to determine, this is because Rust doesn't have its own linker and uses GCC instead. Apparently I need to provide this myself and add this to the ./cargo/config file:

[target.armv7-unknown-linux-gnueabihf]
linker = "c:/path/to/my/gcc/cross/compiler"

Is that right? If so where on Earth can I download such a cross-compiler for Windows and why doesn't rustup install it? Having to compile a cross-compiling version of GCC yourself is the biggest pain of cross-compiling C/C++ programs. Does Rustup really not make this any easier?

Upvotes: 16

Views: 22254

Answers (2)

Hasan A Yousef
Hasan A Yousef

Reputation: 24988

For MacOS better use: musleabihf, for Windows you can use gnueabihf as bellow:

Mac

$ brew install arm-linux-gnueabihf-binutils
$ rustup target add armv7-unknown-linux-musleabihf

In .cargo/config

[build]
target = "armv7-unknown-linux-musleabihf"
[target.armv7-unknown-linux-c]
linker = "arm-linux-gnueabihf-ld"

With simple src/main.rs

fn main() {
    println!("Hello, Raspberry!");
}

Then things are fine:

Hasans-Air:rpi hasan$ cargo build
   Compiling rpi v0.1.0 (/Users/hasan/PycharmProjects/rpi)
    Finished dev [unoptimized + debuginfo] target(s) in 0.41s
Hasans-Air:rpi hasan$ scp target/armv7-unknown-linux-musleabihf/debug/rpi pi@192.168.1.43:
pi@192.168.1.43's password: 
rpi                                                                                         100% 2702KB   2.6MB/s   00:01    
Hasans-Air:rpi hasan$ ssh pi@192.168.1.43 'chmod +x ~/rpi && ~/rpi'
pi@192.168.1.43's password: 
Hello, Raspberry!

Win 10 Get the linker from here, and run:

rustup target add armv7-unknown-linux-gnueabihf

Creating file .cargo/config with content:

[build]
target = "armv7-unknown-linux-gnueabihf"

[target.armv7-unknown-linux-gnueabihf]
linker = "arm-linux-gnueabihf-gcc"

And with simple src/main.rs:

fn main() {
    println!("Hello, Raspberry! from Win 10");
}

I was able to get things done

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Upvotes: 9

Timmmm
Timmmm

Reputation: 97028

Thanks to @Notlikethat's comment:

a) Yes you need to provide your own GCC cross-compiler.

b) You can get one here (select a mingw32 build).

Just unzip linaro's GCC then point cargo to it:

[target.armv7-unknown-linux-gnueabihf]
linker = "C:/Users/me/gcc-linaro-5.3.1-2016.05-i686-mingw32_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc.exe"

It seems to work even though it is arm- and not armv7-. I guess linking doesn't depend on the ISA. Actually I haven't run it yet, but it builds without errors!

Edit:

You can now use armv7-unknown-linux-musleabihf instead and get an actually portable binary (i.e. it doesn't depend on the GNU C library which often causes compatibility issues).

Upvotes: 12

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