Merge pull request #132 from dmitris/crosscompile

add cross-compilation instructions for MacOS

docs/book/aya/crosscompile.md

@@ -0,0 +1,57 @@
+# Cross-compiling aya-based programs
+
+The instructions below show how to cross compile aya eBPF programs on Macs.
+Cross compiling on other systems is possible too and we're going
+to add instructions to do that soon (PRs welcome!).
+
+# Cross-compiling aya-based programs on Mac
+
+Cross compilation should work on both Intel and Apple Silicon Macs.
+
+1. Install `rustup` following the instructions on <https://rustup.rs/>
+1. Install the stable and nightly rust toolchains:
+```bash
+rustup install stable
+rustup toolchain install nightly --component rust-src
+```
+1. Install the [rustup target](https://doc.rust-lang.org/nightly/rustc/platform-support.html#tier-1-with-host-tools) for your Linux target platform:
+```bash
+ARCH=x86_64
+rustup target add ${ARCH}-unknown-linux-musl
+```
+1. Install LLVM with brew:
+```bash
+brew install llvm
+```
+
+1. Install the musl cross compiler:  
+to cross-compile for only `x86_64` targets (the default in musl-cross):
+```bash
+brew install FiloSottile/musl-cross/musl-cross
+```
+to cross-compile for only `aarch64` targets:
+```bash
+brew install FiloSottile/musl-cross/musl-cross --without-x86_64 --with-aarch64
+```
+to cross-compile for both `x86_64` and `aarch64` targets:
+```bash
+brew install FiloSottile/musl-cross/musl-cross --with-aarch64
+```
+See [homebrew-musl-cross](https://github.com/FiloSottile/homebrew-musl-cross)
+for additional platform-specific options.
+
+1. Install bpf-linker:
+```bash
+LLVM_SYS_160_PREFIX=$(brew --prefix llvm) cargo install bpf-linker --no-default-features
+```
+1. Build BPF object files:
+```bash
+cargo xtask build-ebpf --release
+```
+1. Build the userspace code:
+```bash
+RUSTFLAGS="-Clinker=${ARCH}-linux-musl-ld" cargo build --release --target=${ARCH}-unknown-linux-musl
+```
+The cross-compiled program  
+`target/${ARCH}-unknown-linux-musl/release/<program_name>`  
+can be copied to a Linux server or VM and run there.

mkdocs.yml

@@ -73,6 +73,7 @@ nav:
       - Reading Values From A Context: book/aya/context.md
       - Using aya-tool: book/aya/aya-tool.md
       - Using aya-log: book/aya/aya-log.md
+      - Cross-compilation: book/aya/crosscompile.md
     - Program Types:
       - book/programs/index.md
       - Probes: book/programs/probes.md