How to make cross-compilation work with buildroot

doc/cross-compile/buildroot.md

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+
+## 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` tool: `curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh`
+
+3. add the arm64 target for rust: `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:
+   ```
+   [target.aarch64-unknown-linux-gnu]
+   linker = "aarch64-buildroot-linux-gnu-gcc"
+   ```
+   "aarch64-buildroot-linux-gnu-gcc" is your real cross-compilation tool name
+
+
+6. source your cross-compilation buildroot environment: `source /to/your/environment-setup`, this file should be in your buildroot folder
+
+7. add the buildroot sysroot on host PC environment: `export BINDGEN_EXTRA_CLANG_ARGS="--sysroot=/to/your/sysroot"`
+
+8. cd iceoryx2 
+
+9. cmake -S . -B build -DBUILD_EXAMPLES=ON -DCMAKE_INSTALL_PREFIX=../_OUTPUT -DRUST_TARGET_TRIPLET='aarch64-unknown-linux-gnu'
+
+10. cd build
+
+11. make -j8
+
+12. make install
+
+Finally, you can get the arm64 libs, include files in _OUTPUT folder.