crosscompiler

A crosscompiler is a compiler that runs on a host machine but generates executable code for a different target architecture. It is part of a cross toolchain that may also include an assembler, linker, target libraries, and header files. Crosscompilers are used when the host cannot run binaries for the target or when software is developed for devices with different processors, limited resources, or different operating systems.

How it works: The crosscompiler accepts source code and uses a target-specific backend to produce object files for the target architecture. The accompanying linker combines these objects with target libraries to create executables or libraries suitable for the target system. A sysroot or target filesystem layout provides the necessary headers and libraries, ensuring proper ABI and linkage. The host and target are distinguished by tool prefixes and triplets, such as arm-none-eabi- or aarch64-linux-gnu-.

Common use cases: Crosscompilers are fundamental in embedded systems development, mobile and IoT software, and operating system porting. They enable building software on a powerful host machine while targeting resource-constrained devices. Popular examples include GCC-based cross compilers like arm-none-eabi-gcc and aarch64-linux-gnu-gcc, as well as Clang/LLVM cross toolchains. Build systems and runtimes such as Buildroot, OpenEmbedded, and Crosstool-NG automate the creation of complete cross toolchains.

Challenges and considerations: Working with crosscompilers involves addressing ABI differences, endianness, and varying C library implementations. Debugging can be more complex, often requiring remote debugging tools (for example, gdbserver) or simulators. Maintaining compatibility between host tools and target libraries, and keeping the toolchain up to date with target platforms, are ongoing concerns in cross-development.