Rust Cross-Compilation Purpose Guide agents through Rust cross-compilation: adding rustup targets, using cross for hermetic Docker-based cross-builds, cargo-zigbuild for zero-setup cross-compilation, .cargo/config.toml configuration, and embedded bare-metal targets. Triggers "How do I cross-compile Rust for ARM/aarch64?" "How do I build a Rust binary for a different OS?" "How do I use the cross tool for Rust cross-compilation?" "How do I build Rust for embedded (no_std) targets?" "How do I use cargo-zigbuild?" "My cross-compiled Rust binary won't run on the target" Workflow 1. Add a rustup target

List installed targets

rustup target list --installed

List all available targets

rustup target list

Add a target

rustup target add aarch64-unknown-linux-gnu rustup target add x86_64-unknown-linux-musl

static Linux

rustup target add wasm32-unknown-unknown

WASM

rustup target add thumbv7m-none-eabi

Cortex-M

Build for target

cargo build --target aarch64-unknown-linux-gnu --release 2. Common target triples Target Use case x86_64-unknown-linux-gnu Linux x86-64 (glibc) x86_64-unknown-linux-musl Linux x86-64 (musl, static) aarch64-unknown-linux-gnu ARM64 Linux (Raspberry Pi 4, AWS Graviton) aarch64-unknown-linux-musl ARM64 Linux static x86_64-pc-windows-gnu Windows x86-64 (MinGW) x86_64-pc-windows-msvc Windows x86-64 (MSVC) x86_64-apple-darwin macOS x86-64 aarch64-apple-darwin macOS Apple Silicon wasm32-unknown-unknown WASM (browser) wasm32-wasi WASM with WASI thumbv7m-none-eabi Cortex-M3 bare metal thumbv7em-none-eabihf Cortex-M4/M7 with FPU riscv32imac-unknown-none-elf RISC-V 32-bit bare metal 3. cross tool (Docker-based, easiest) cross uses pre-built Docker images with the correct cross-toolchain:

Install

cargo install cross

Build (drop-in replacement for cargo)

cross build --target aarch64-unknown-linux-gnu --release cross test --target aarch64-unknown-linux-gnu

Cross.toml — project configuration

Cross.toml

[ target.aarch64-unknown-linux-gnu ] image = "ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main" pre-build = [ "apt-get update && apt-get install -y libssl-dev:arm64" ] [ build.env ] passthrough = [ "PKG_CONFIG_PATH" , "OPENSSL_DIR" ] 4. cargo-zigbuild (zero-setup, uses zig cc) zig cc ships a complete C cross-toolchain — no system cross-compiler needed:

Install

cargo install cargo-zigbuild

Also needs zig installed: https://ziglang.org/download/

Build (no Docker, no system cross-compiler)

cargo zigbuild --target aarch64-unknown-linux-gnu --release cargo zigbuild --target x86_64-unknown-linux-musl --release

Target with glibc version (important for compatibility)

cargo zigbuild --target aarch64-unknown-linux-gnu.2.17 --release

This builds against glibc 2.17 (very compatible)

Windows from Linux/macOS

cargo zigbuild --target x86_64-pc-windows-gnu --release cargo-zigbuild advantages over cross : No Docker required Faster (no container startup) Works for most targets out of the box Supports precise glibc version targeting 5. .cargo/config.toml for cross targets

.cargo/config.toml

[ target.aarch64-unknown-linux-gnu ] linker = "aarch64-linux-gnu-gcc"

System cross-linker

or with zig:

linker = "zig"

rustflags = ["-C", "link-arg=cc", "-C", "link-arg=-target", "-C", "link-arg=aarch64-linux-gnu"]

[ target.x86_64-unknown-linux-musl ] linker = "x86_64-linux-musl-gcc" rustflags = [ "-C" , "target-feature=+crt-static" ] [ target.wasm32-unknown-unknown ] runner = "wasmtime"

Run WASM tests with wasmtime

[ target.thumbv7m-none-eabi ] runner = "qemu-arm -cpu cortex-m3" 6. Static binaries with musl

Add musl target

rustup target add x86_64-unknown-linux-musl

Build statically linked binary

cargo build --target x86_64-unknown-linux-musl --release

Verify it's static

file target/x86_64-unknown-linux-musl/release/myapp

→ ELF 64-bit, statically linked, not stripped

Or with cargo-zigbuild (easier musl)

cargo zigbuild --target x86_64-unknown-linux-musl --release 7. Embedded bare-metal (#[no_std])

.cargo/config.toml

[ build ] target = "thumbv7em-none-eabihf"

Set default target

[ target.'cfg(target_arch = "arm")' ] runner = "probe-run --chip STM32F411CE" // src/main.rs

![no_std]

![no_main]

use core :: panic :: PanicInfo ;

[cortex_m_rt::entry]

fn main ( ) -> ! { loop { } }

[panic_handler]

fn panic ( _info : & PanicInfo ) -> ! { loop { } }

Cargo.toml

[ dependencies ] cortex-m = "0.7" cortex-m-rt = "0.7" [ profile.release ] opt-level = "z" lto = true codegen-units = 1 panic = "abort" cargo build --release

Uses default target from .cargo/config.toml

For target triple reference and embedded setup details, see references/ .