官方下载下来的buildroot源码包在解压后，是一个名为buildroot的文件夹，它下面的目录/文件结构如下：
Makefile - *makefile，编译总入口
Config.in - *Config.in文件，包含主要的配置信息，同时还会引用其它Config.in文件（比如arch linux toolchain等目录下的Config.in文件）
arch/ - Config.in.* 文件定义了不同的架构 (processor type, ABI, floating point, etc.)
toolchain/ - 工具链
▶ packages for generating or using toolchains
▶ toolchain/ virtual package that depends on either toolchain-buildroot or toolchain-external
▶ toolchain-buildroot/ virtual package to build the internal toolchain
▶ toolchain-external/ package to handle external toolchains
system/ - 根文件系统框架
▶ skeleton/ the rootfs skeleton
▶ Config.in, options for system-wide features like init system, /dev handling, etc.
linux/ - linux内核代码
▶ linux.mk, the Linux kernel package
package/ - 软件包
▶ all the user space packages (1600+)
▶ busybox/, gcc/, qt5/, etc.
▶ pkg-generic.mk, core package infrastructure
▶ pkg-cmake.mk, pkg-autotools.mk, pkg-perl.mk, etc. Specialized package infrastructures
fs/ - 文件系统
▶ logic to generate filesystem images in various formats
▶ common.mk, common logic
▶ cpio/, ext2/, squashfs/, tar/, ubifs/, etc.
boot/ - 引导系统
▶ bootloader packages
▶ at91bootstrap3/, barebox/, grub/, syslinux/, uboot/, etc.
configs/ - 针对不同硬件平台的特有配置文件合集
▶ default configuration files for various platforms
▶ similar to kernel defconfigs
▶ atmel_xplained_defconfig, beaglebone_defconfig,raspberrypi_defconfig, etc.
board/ - 针对不同硬件平台的特有配置文件/脚本/patch
▶ board-specific files (kernel configuration files, kernel patches, image flashing scripts, etc.)
▶ typically go together with a defconfig in configs/
support/ - 其它
▶ misc utilities (kconfig code, libtool patches, download helpers, and more.)
docs/ - 文档
▶ Buildroot documentation
▶ Written in AsciiDoc, can generate HTML, PDF, TXT versions:make manual
▶ 90 pages PDF document
▶ Also available pre-generated online.
▶ http://buildroot.org/downloads/manual/manual.html