The Kernel Source Tree

The kernel source tree is divided into a number of directories, most of which contain many more subdirectories. The directories in the root of the source tree, along with their descriptions, are listed in Table 2.1.

Table 2.1. Directories in the Root of the Kernel Source Tree

Directory	Description
arch	Architecture-specific source
crypto	Crypto API
Documentation	Kernel source documentation
drivers	Device drivers
fs	The VFS and the individual file systems
include	Kernel headers
init	Kernel boot and initialization
ipc	Interprocess communication code
kernel	Core subsystems, such as the scheduler
lib	Helper routines
mm	Memory management subsystem and the VM
net	Networking subsystem
scripts	Scripts used to build the kernel
security	Linux Security Module
sound	Sound subsystem
usr	Early user-space code (called initramfs)

A number of files in the root of the source tree deserve mention.The file COPYING is the kernel license (the GNU GPL v2). CREDITS is a listing of developers with a more than trivial amount of code in the kernel. MAINTAINERS lists the names of the individuals who maintain subsystems and drivers in the kernel. Finally, Makefile is the base kernel Makefile.