Buildroot

Buildroot is an open-source build system and collection of Makefiles designed to simplify the creation of complete embedded Linux systems. It automates the process of cross-compiling a toolchain, a target root filesystem, a Linux kernel, and a bootloader for a chosen hardware target. With a single configuration, developers select the desired architecture, C library, kernel version, bootloader, and user-space packages. Buildroot then fetches sources, applies patches, compiles components, and assembles a bootable image.

Configuration is performed through a menu-driven interface (such as make menuconfig) or by supplying predefined configuration files. The configuration uses a structured set of options (BR2_ variables) and includes automatic dependency resolution to ensure required packages and components are built consistently.

Buildroot includes a large collection of packages and a packaging infrastructure. Each package provides build instructions, and Buildroot handles downloading sources, applying patches, configuring, building, and installing packages into the target root filesystem. Users can enable or disable packages, select versions, and tune build options to fit specific device requirements.

Output from a Buildroot build is a ready-to-flash embedded Linux system, including a cross-compiler toolchain, a target root filesystem, a kernel image, and a bootloader binary. It supports multiple bootloaders, such as U-Boot, and can produce various image formats suitable for different hardware boards and storage media.

Supported architectures include a broad range such as ARM, ARM64, x86, MIPS, and PowerPC. Buildroot is widely used in the embedded Linux community to generate custom firmware and device images in a repeatable, maintainable manner.