BuildRoot using the 2 source file directory structure

The official download down the BuildRoot source package after decompression, is a folder named BuildRoot, the following directory/file structure is as follows:

Makefile-Top Makefile, compiling the total entrance

Config.in-A top-level config.in file that contains the main configuration information, as well as references to other config.in files (such as config.in files in directories such as the Arch Linux toolchain)

The arch/-config.in.* file defines different schemas (processor type, ABI, floating point, etc.)

toolchain/-Tool Chain
? Packages for generating or using toolchains
? Toolchain/virtual package, 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/-Root File system framework
? Skeleton/the Rootfs Skeleton
? config.in, options for System-wide features like init system,/dev handling, etc.
linux/-Linux Kernel code
? LINUX.MK, the Linux kernel package

package/-Package
? 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/-File system
? Logic to generate filesystem images in various formats
? Common.mk, Common logic
? cpio/, ext2/, squashfs/, tar/, ubifs/, etc.
boot/-Boot System
? Bootloader Packages
? at91bootstrap3/, barebox/, grub/, syslinux/, uboot/, etc.

configs/-Unique configuration file collection for different hardware platforms
? Default configuration files for various platforms
? Similar to Kernel Defconfigs
? Atmel_xplained_defconfig, Beaglebone_defconfig,raspberrypi_defconfig, etc.

board/-Unique profile/script for different hardware platforms/patch
? board-specific files (kernel configuration files, kernel patches, image flashing scripts, etc.)
? Typically go together with a defconfig in configs/
support/-Other
? Misc Utilities (Kconfig code, Libtool patches, download helpers, and more.)

docs/-Documentation
? BuildRoot documentation
? Written in AsciiDoc, can generate HTML, PDF, TXT versions:make Manual
? Pages PDF Document
? Also available pre-generated online.
? Http://buildroot.org/downloads/manual/manual.html

BuildRoot using the 2 source file directory structure