[#453] Document how to make cross-compilation work with buildroot

doc/cross-compile/buildroot.md

@@ -0,0 +1,52 @@
+# How to make cross-compilation work with buildroot
+
+1. Install the build dependencies on your host PC, like: cmake, g++, clang...
+
+2. Install the `rust` toolchain:
+
+   ```console
+   curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+   ```
+
+3. Add the arm64 target for Rust:
+
+   ```console
+   rustup target add aarch64-unknown-linux-gnu
+   ```
+
+4. Modify the arm64 target name to suit your cross-compilation tool, need to
+   create this file `~/.cargo/config.toml`, add the below code,
+   "aarch64-buildroot-linux-GNU-gcc" which is your real cross-compilation tool
+   name:
+   ```console
+   [target.aarch64-unknown-linux-gnu]
+   linker = "aarch64-buildroot-linux-gnu-gcc"
+   ```
+5. Source your cross-compilation buildroot environment:
+
+   ```console
+   source /to/your/environment-setup 
+   ```
+
+   The `environment-setup` file should be in your buildroot directory.
+
+6. Add the buildroot sysroot on host PC environment:
+
+   ```console
+   export BINDGEN_EXTRA_CLANG_ARGS="--sysroot=/to/your/sysroot"
+   ```
+
+7. Change to the iceoryx2 directory
+
+   ```console
+   cd iceoryx2
+   ```
+
+8. Configure, build and install iceoryx2
+   ```console
+   cmake -S . -B build -DBUILD_EXAMPLES=ON -DCMAKE_INSTALL_PREFIX=../\_OUTPUT -DRUST_TARGET_TRIPLET='aarch64-unknown-linux-GNU'
+   cmake --build build
+   cmake --install build
+   ```
+
+Finally, you can get the arm64 libs, include files in the `_OUTPUT` directory.