Crossbuild

Crossbuild, or cross-building, is the process of compiling software on a host system to produce executables that run on a different target architecture. It is common when developing for embedded devices or platforms where native builds are impractical or slow. The core idea is to use a cross-compiler and a target-friendly set of libraries and headers (a sysroot) so the resulting binaries can operate on the target without relying on the host's toolchain.

Key concepts include the host (the build system), the target (the produced binaries’ architecture), and the toolchain (cross-compiler, linker, and associated utilities). A triplet or target triplet (such as x86_64-unknown-linux-gnu or arm-linux-gnueabihf) identifies the cross-compiler and libraries to use. The sysroot provides the target’s libraries and headers, ensuring correct ABI and runtime behavior.

Typical workflow involves installing a cross-toolchain for the target, configuring the build system with appropriate host/target settings, supplying a sysroot, and then compiling and linking. Build systems such as Autotools, CMake, Meson, and Bazel offer modes or toolchain files to support cross-building. Specialized environments like Buildroot, Yocto Project, or OpenWrt automate cross-building for embedded devices, often generating complete images or packages.

Challenges include differences in endianness and ABI, availability of target libraries, C runtime compatibility, dynamic vs static linking, and debugging across architectures. Testing often relies on emulation (e.g., QEMU) or hardware.

Common examples include cross-compiling C/C++ programs for ARM on x86 hosts or building Windows binaries from Linux using MinGW-w64. Crossbuild enables development for multiple platforms from a single environment.