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Linux Kernel Makefiles
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This document describes the Linux kernel Makefiles.
Overview
========
The Makefiles have five parts::
Makefile the top Makefile.
.config the kernel configuration file.
arch/$(SRCARCH)/Makefile the arch Makefile.
scripts/Makefile.* common rules etc. for all kbuild Makefiles.
kbuild Makefiles exist in every subdirectory
The top Makefile reads the .config file, which comes from the kernel
configuration process.
The top Makefile is responsible for building two major products: vmlinux
(the resident kernel image) and modules (any module files).
It builds these goals by recursively descending into the subdirectories of
the kernel source tree.
The list of subdirectories which are visited depends upon the kernel
configuration. The top Makefile textually includes an arch Makefile
with the name arch/$(SRCARCH)/Makefile. The arch Makefile supplies
architecture-specific information to the top Makefile.
Each subdirectory has a kbuild Makefile which carries out the commands
passed down from above. The kbuild Makefile uses information from the
.config file to construct various file lists used by kbuild to build
any built-in or modular targets.
scripts/Makefile.* contains all the definitions/rules etc. that
are used to build the kernel based on the kbuild makefiles.
Who does what
=============
People have four different relationships with the kernel Makefiles.
*Users* are people who build kernels. These people type commands such as
``make menuconfig`` or ``make``. They usually do not read or edit
any kernel Makefiles (or any other source files).
*Normal developers* are people who work on features such as device
drivers, file systems, and network protocols. These people need to
maintain the kbuild Makefiles for the subsystem they are
working on. In order to do this effectively, they need some overall
knowledge about the kernel Makefiles, plus detailed knowledge about the
public interface for kbuild.
*Arch developers* are people who work on an entire architecture, such
as sparc or x86. Arch developers need to know about the arch Makefile
as well as kbuild Makefiles.
*Kbuild developers* are people who work on t
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