LINUX-Makefile全解析(编译体系)-基于Linux3.25内核

第一部分

第一节:参考文献

参考文献1.GNU make中文手册V3.8-徐海兵;
参考文献2.跟我一起写 Makefile--01(zz 陈皓)http://csc80.bokee.com/blog/1661375.html
参考文献3. GNU Make V3.79 Richard M. Stallman and Roland McGrath
参考文献4. Linux内核构建系统之1-10 巨立安科技Yihe.Chen的博客http://www.juliantec.info/julblog/yihect/linux-kernel-build-system-1
参考文献5.LINUX 编译系统hj_shen的博客  http://blog.csdn.net/hj_shen/article/details/2968630
参考文献6.linux make menuconfig 执行流程小结boyskung的博客 http://blog.csdn.net/BoySKung/article/details/3596762
参考文献7.Linux 3.0内核Makefile分析  mbtrend的博客http://blog.csdn.net/mbtrend/article/details/3016889
参考文献8.内核Kbuild 学习 emmoblin 的博客http://blog.chinaunix.net/space.php?uid=20778443&do=blog&id=103963
参考文献9.内核编译系统探秘之一 if_changed_rule  yuanliixjtu的博客http://blog.sina.com.cn/s/blog_61c81f910100phiq.html
参考文献10.linux 顶层Makefile执行的流程 搏仕的空间 http://hi.baidu.com/%B2%AB%CA%CB/blog/item/d0ca98d89f3068c38c1029e5.html原作者也可能是:耶和华的大卫http://www.360doc.com/content/11/1107/22/1317564_162638750.shtml,抱歉啊,作者看到了说声啊。

***********************************************************************************************************************************************************************************************************************************************************************

第二节:本文的主要内容

1.编译出第一个镜像-讲述操作过程
2.Linux的编译体系概述
3.顶层Makefile的架构
4.Make %config的执行过程--讲述原理和使用方法
5.子目录的编译
6.Vmlinux的编译过程
7.内部和外部模块的编译过程
8.Uimage Zimage的编译过程
10.一个完整的例子
9.怎么添加一个自己的驱动
10顶层Makefile注释

11关键变量、表达式和语法注释


第二部分 主要内容

第一节 编译出第一个镜像

作者使用的试验环境是VMware Workstation虚拟机下安装的ubuntu-10.04.3-desktop-i386。
1.获得Linux内核源代码,比如从www.kernel.org处。

2.建一工作目录,比如在当前用户的目录下:~,mkdir linux_3.2.5,然后将获得的源代码复制到该目录下解压,
tar -jxvf linux-3.2.5.tar.bz2 解压后即在~/linux_3.2.5/linux_3.2.5/下获得了源代码树

3.这是假如直接在代码树顶层~/linux_3.2.5/linux_3.2.5/下运行make 则会报错(用户名瞎取的啊):
guanyu@guanyu:~/linux_3.2.5/linux-3.2.5$ make
scripts/kconfig/conf --silentoldconfig Kconfig
***
*** Configuration file ".config" not found!
***
*** Please run some configurator (e.g. "make oldconfig" 


or
*** "make menuconfig" or "make xconfig").
***
make[2]: *** [silentoldconfig] Error 1
make[1]: *** [silentoldconfig] Error 2
make: *** No rule to make target 
`include/config/auto.conf', needed by 
`include/config/kernel.release'.  Stop.
guanyu@guanyu:~/linux_3.2.5/linux-3.2.5$ ^C
guanyu@guanyu:~/linux_3.2.5/linux-3.2.5$ 
意思就是说没有.config,至于为什么需要.config后文会详细解释。

4.运行make menuconfig 生产.config,不用改任何选项,第一次运行make menuconfig时,提示:

*** Unable to find the ncurses libraries or the
 *** required header files.
 *** 'make menuconfig' requires the ncurses libraries.
 *** 
 *** Install ncurses (ncurses-devel) and try again.
 *** 
make[1]: *** [scripts/kconfig/dochecklxdialog] Error 1
make: *** [menuconfig] Error 2
解决办法是用root账户登录,联网,然后运行
apt-get install libncurses5-dev  

5.退出make menuconfig 后执行make命令,
6执行make bzImage,就可以编译出一个镜像了。默认是x86的。会提示Kernel: arch/x86/boot/bzImage is ready ,其它架构的后面再说啦,先有个感性的认识还是好的。

第二节.Linux的编译体系概述

第三节 顶层Makefile的架构

   顶层的Makefile主要可分为四个部分,第一部分1-78行主要是定义一些变量、根据输入命令判断命令显示、代码的检测等,具体可见后文顶层Makefile的注释。剩下的三部分分别称为甲乙丙。 如下图所示:
    甲:

   乙

丙部分1560-1566行:只有3句话,定义伪目标:
PHONY += FORCE
FORCE:
.PHONY: $(PHONY)

第四节 Make %config的执行过程与使用方法

第五节子目录的编译

第六节Vmlinux的编译过程

第七节内部和外部模块的编译过程

第八节Uimage Zimage的编译过程

VERSION = 3
PATCHLEVEL = 2
SUBLEVEL = 5
EXTRAVERSION =
NAME = Saber-toothed Squirrel

# *DOCUMENTATION*
# To see a list of typical targets execute "make help"
# More info can be located in ./README
# Comments in this file are targeted only to the developer, do not
# expect to learn how to build the kernel reading this file.

# Do not:
# o  use make's built-in rules and variables
#    (this increases performance and avoids hard-to-debug behaviour);
# o  print "Entering directory ...";
MAKEFLAGS += -rR --no-print-directory

# Avoid funny character set dependencies
unexport LC_ALL
LC_COLLATE=C
LC_NUMERIC=C
export LC_COLLATE LC_NUMERIC

# We are using a recursive build, so we need to do a little thinking
# to get the ordering right.
#
# Most importantly: sub-Makefiles should only ever modify files in
# their own directory. If in some directory we have a dependency on
# a file in another dir (which doesn't happen often, but it's often
# unavoidable when linking the built-in.o targets which finally
# turn into vmlinux), we will call a sub make in that other dir, and
# after that we are sure that everything which is in that other dir
# is now up to date.
#
# The only cases where we need to modify files which have global
# effects are thus separated out and done before the recursive
# descending is started. They are now explicitly listed as the
# prepare rule.

# To put more focus on warnings, be less verbose as default
# Use 'make V=1' to see the full commands

ifeq ("$(origin V)", "command line")
  KBUILD_VERBOSE = $(V)
endif
ifndef KBUILD_VERBOSE
  KBUILD_VERBOSE = 0
endif

# Call a source code checker (by default, "sparse") as part of the
# C compilation.
#
# Use 'make C=1' to enable checking of only re-compiled files.
# Use 'make C=2' to enable checking of *all* source files, regardless
# of whether they are re-compiled or not.
#
# See the file "Documentation/sparse.txt" for more details, including
# where to get the "sparse" utility.

ifeq ("$(origin C)", "command line")
  KBUILD_CHECKSRC = $(C)
endif
ifndef KBUILD_CHECKSRC
  KBUILD_CHECKSRC = 0
endif

# Use make M=dir to specify directory of external module to build
# Old syntax make ... SUBDIRS=$PWD is still supported
# Setting the environment variable KBUILD_EXTMOD take precedence
ifdef SUBDIRS
  KBUILD_EXTMOD ?= $(SUBDIRS)
endif

ifeq ("$(origin M)", "command line")
  KBUILD_EXTMOD := $(M)
endif

# kbuild supports saving output files in a separate directory.
# To locate output files in a separate directory two syntaxes are supported.
# In both cases the working directory must be the root of the kernel src.
# 1) O=
# Use "make O=dir/to/store/output/files/"
#
# 2) Set KBUILD_OUTPUT
# Set the environment variable KBUILD_OUTPUT to point to the directory
# where the output files shall be placed.
# export KBUILD_OUTPUT=dir/to/store/output/files/
# make
#
# The O= assignment takes precedence over the KBUILD_OUTPUT environment
# variable.


# KBUILD_SRC is set on invocation of make in OBJ directory
# KBUILD_SRC is not intended to be used by the regular user (for now)
ifeq ($(KBUILD_SRC),)

# OK, Make called in directory where kernel src resides
# Do we want to locate output files in a separate directory?
ifeq ("$(origin O)", "command line")
  KBUILD_OUTPUT := $(O)
endif

ifeq ("$(origin W)", "command line")
  export KBUILD_ENABLE_EXTRA_GCC_CHECKS := $(W)
endif

# That's our default target when none is given on the command line
PHONY := _all
_all:

# Cancel implicit rules on top Makefile
$(CURDIR)/Makefile Makefile: ;

ifneq ($(KBUILD_OUTPUT),)
# Invoke a second make in the output directory, passing relevant variables
# check that the output directory actually exists
saved-output := $(KBUILD_OUTPUT)
KBUILD_OUTPUT := $(shell cd $(KBUILD_OUTPUT) && /bin/pwd)
$(if $(KBUILD_OUTPUT),, \
     $(error output directory "$(saved-output)" does not exist))

PHONY += $(MAKECMDGOALS) sub-make

$(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
	$(Q)@:

sub-make: FORCE
	$(if $(KBUILD_VERBOSE:1=),@)$(MAKE) -C $(KBUILD_OUTPUT) \
	KBUILD_SRC=$(CURDIR) \
	KBUILD_EXTMOD="$(KBUILD_EXTMOD)" -f $(CURDIR)/Makefile \
	$(filter-out _all sub-make,$(MAKECMDGOALS))

# Leave processing to above invocation of make
skip-makefile := 1
endif # ifneq ($(KBUILD_OUTPUT),)
endif # ifeq ($(KBUILD_SRC),)

# We process the rest of the Makefile if this is the final invocation of make
ifeq ($(skip-makefile),)

# If building an external module we do not care about the all: rule
# but instead _all depend on modules
PHONY += all
ifeq ($(KBUILD_EXTMOD),)
_all: all
else
_all: modules
endif

srctree		:= $(if $(KBUILD_SRC),$(KBUILD_SRC),$(CURDIR))
objtree		:= $(CURDIR)
src		:= $(srctree)
obj		:= $(objtree)

VPATH		:= $(srctree)$(if $(KBUILD_EXTMOD),:$(KBUILD_EXTMOD))

export srctree objtree VPATH


# SUBARCH tells the usermode build what the underlying arch is.  That is set
# first, and if a usermode build is happening, the "ARCH=um" on the command
# line overrides the setting of ARCH below.  If a native build is happening,
# then ARCH is assigned, getting whatever value it gets normally, and 
# SUBARCH is subsequently ignored.

SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
				  -e s/arm.*/arm/ -e s/sa110/arm/ \
				  -e s/s390x/s390/ -e s/parisc64/parisc/ \
				  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
				  -e s/sh[234].*/sh/ )

# Cross compiling and selecting different set of gcc/bin-utils
# ---------------------------------------------------------------------------
#
# When performing cross compilation for other architectures ARCH shall be set
# to the target architecture. (See arch/* for the possibilities).
# ARCH can be set during invocation of make:
# make ARCH=ia64
# Another way is to have ARCH set in the environment.
# The default ARCH is the host where make is executed.

# CROSS_COMPILE specify the prefix used for all executables used
# during compilation. Only gcc and related bin-utils executables
# are prefixed with $(CROSS_COMPILE).
# CROSS_COMPILE can be set on the command line
# make CROSS_COMPILE=ia64-linux-
# Alternatively CROSS_COMPILE can be set in the environment.
# A third alternative is to store a setting in .config so that plain
# "make" in the configured kernel build directory always uses that.
# Default value for CROSS_COMPILE is not to prefix executables
# Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
export KBUILD_BUILDHOST := $(SUBARCH)
ARCH		?= $(SUBARCH)
CROSS_COMPILE	?= $(CONFIG_CROSS_COMPILE:"%"=%)

# Architecture as present in compile.h
UTS_MACHINE 	:= $(ARCH)
SRCARCH 	:= $(ARCH)

# Additional ARCH settings for x86
ifeq ($(ARCH),i386)
        SRCARCH := x86
endif
ifeq ($(ARCH),x86_64)
        SRCARCH := x86
endif

# Additional ARCH settings for sparc
ifeq ($(ARCH),sparc32)
       SRCARCH := sparc
endif
ifeq ($(ARCH),sparc64)
       SRCARCH := sparc
endif

# Additional ARCH settings for sh
ifeq ($(ARCH),sh64)
       SRCARCH := sh
endif

# Additional ARCH settings for tile
ifeq ($(ARCH),tilepro)
       SRCARCH := tile
endif
ifeq ($(ARCH),tilegx)
       SRCARCH := tile
endif

# Where to locate arch specific headers
hdr-arch  := $(SRCARCH)

ifeq ($(ARCH),m68knommu)
       hdr-arch  := m68k
endif

KCONFIG_CONFIG	?= .config
export KCONFIG_CONFIG

# SHELL used by kbuild
CONFIG_SHELL := $(shell if [ -x "$BASH" ]; then echo $BASH; \
	  else if [ -x /bin/bash ]; then echo /bin/bash; \
	  else echo sh; fi ; fi)

HOSTCC       = gcc
HOSTCXX      = g++
HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
HOSTCXXFLAGS = -O2

# Decide whether to build built-in, modular, or both.
# Normally, just do built-in.

KBUILD_MODULES :=
KBUILD_BUILTIN := 1

#	If we have only "make modules", don't compile built-in objects.
#	When we're building modules with modversions, we need to consider
#	the built-in objects during the descend as well, in order to
#	make sure the checksums are up to date before we record them.

ifeq ($(MAKECMDGOALS),modules)
  KBUILD_BUILTIN := $(if $(CONFIG_MODVERSIONS),1)
endif

#	If we have "make  modules", compile modules
#	in addition to whatever we do anyway.
#	Just "make" or "make all" shall build modules as well

ifneq ($(filter all _all modules,$(MAKECMDGOALS)),)
  KBUILD_MODULES := 1
endif

ifeq ($(MAKECMDGOALS),)
  KBUILD_MODULES := 1
endif

export KBUILD_MODULES KBUILD_BUILTIN
export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD

# Beautify output
# ---------------------------------------------------------------------------
#
# Normally, we echo the whole command before executing it. By making
# that echo $($(quiet)$(cmd)), we now have the possibility to set
# $(quiet) to choose other forms of output instead, e.g.
#
#         quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
#         cmd_cc_o_c       = $(CC) $(c_flags) -c -o $@ {1}lt;
#
# If $(quiet) is empty, the whole command will be printed.
# If it is set to "quiet_", only the short version will be printed. 
# If it is set to "silent_", nothing will be printed at all, since
# the variable $(silent_cmd_cc_o_c) doesn't exist.
#
# A simple variant is to prefix commands with $(Q) - that's useful
# for commands that shall be hidden in non-verbose mode.
#
#	$(Q)ln $@ :<
#
# If KBUILD_VERBOSE equals 0 then the above command will be hidden.
# If KBUILD_VERBOSE equals 1 then the above command is displayed.

ifeq ($(KBUILD_VERBOSE),1)
  quiet =
  Q =
else
  quiet=quiet_
  Q = @
endif

# If the user is running make -s (silent mode), suppress echoing of
# commands

ifneq ($(findstring s,$(MAKEFLAGS)),)
  quiet=silent_
endif

export quiet Q KBUILD_VERBOSE


# Look for make include files relative to root of kernel src
MAKEFLAGS += --include-dir=$(srctree)

# We need some generic definitions (do not try to remake the file).
$(srctree)/scripts/Kbuild.include: ;
include $(srctree)/scripts/Kbuild.include

# Make variables (CC, etc...)

AS		= $(CROSS_COMPILE)as
LD		= $(CROSS_COMPILE)ld
CC		= $(CROSS_COMPILE)gcc
CPP		= $(CC) -E
AR		= $(CROSS_COMPILE)ar
NM		= $(CROSS_COMPILE)nm
STRIP		= $(CROSS_COMPILE)strip
OBJCOPY		= $(CROSS_COMPILE)objcopy
OBJDUMP		= $(CROSS_COMPILE)objdump
AWK		= awk
GENKSYMS	= scripts/genksyms/genksyms
INSTALLKERNEL  := installkernel
DEPMOD		= /sbin/depmod
KALLSYMS	= scripts/kallsyms
PERL		= perl
CHECK		= sparse

CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
		  -Wbitwise -Wno-return-void $(CF)
CFLAGS_MODULE   =
AFLAGS_MODULE   =
LDFLAGS_MODULE  =
CFLAGS_KERNEL	=
AFLAGS_KERNEL	=
CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage


# Use LINUXINCLUDE when you must reference the include/ directory.
# Needed to be compatible with the O= option
LINUXINCLUDE    := -I$(srctree)/arch/$(hdr-arch)/include \
                   -Iarch/$(hdr-arch)/include/generated -Iinclude \
                   $(if $(KBUILD_SRC), -I$(srctree)/include) \
                   -include $(srctree)/include/linux/kconfig.h

KBUILD_CPPFLAGS := -D__KERNEL__

KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
		   -fno-strict-aliasing -fno-common \
		   -Werror-implicit-function-declaration \
		   -Wno-format-security \
		   -fno-delete-null-pointer-checks
KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
KBUILD_AFLAGS   := -D__ASSEMBLY__
KBUILD_AFLAGS_MODULE  := -DMODULE
KBUILD_CFLAGS_MODULE  := -DMODULE
KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds

# Read KERNELRELEASE from include/config/kernel.release (if it exists)
KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)

export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
export CPP AR NM STRIP OBJCOPY OBJDUMP
export MAKE AWK GENKSYMS INSTALLKERNEL PERL UTS_MACHINE
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS

export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV
export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
export KBUILD_ARFLAGS

# When compiling out-of-tree modules, put MODVERDIR in the module
# tree rather than in the kernel tree. The kernel tree might
# even be read-only.
export MODVERDIR := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_versions

# Files to ignore in find ... statements

RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o -name CVS -o -name .pc -o -name .hg -o -name .git \) -prune -o
export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn --exclude CVS --exclude .pc --exclude .hg --exclude .git

# ===========================================================================
# Rules shared between *config targets and build targets

# Basic helpers built in scripts/
PHONY += scripts_basic
scripts_basic:
	$(Q)$(MAKE) $(build)=scripts/basic
	$(Q)rm -f .tmp_quiet_recordmcount

# To avoid any implicit rule to kick in, define an empty command.
scripts/basic/%: scripts_basic ;

PHONY += outputmakefile
# outputmakefile generates a Makefile in the output directory, if using a
# separate output directory. This allows convenient use of make in the
# output directory.
outputmakefile:
ifneq ($(KBUILD_SRC),)
	$(Q)ln -fsn $(srctree) source
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile \
	    $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
endif

# Support for using generic headers in asm-generic
PHONY += asm-generic
asm-generic:
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
	            obj=arch/$(SRCARCH)/include/generated/asm

# To make sure we do not include .config for any of the *config targets
# catch them early, and hand them over to scripts/kconfig/Makefile
# It is allowed to specify more targets when calling make, including
# mixing *config targets and build targets.
# For example 'make oldconfig all'.
# Detect when mixed targets is specified, and make a second invocation
# of make so .config is not included in this case either (for *config).

no-dot-config-targets := clean mrproper distclean \
			 cscope gtags TAGS tags help %docs check% coccicheck \
			 include/linux/version.h headers_% \
			 kernelversion %src-pkg

config-targets := 0
mixed-targets  := 0
dot-config     := 1

ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
	ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
		dot-config := 0
	endif
endif

ifeq ($(KBUILD_EXTMOD),)
        ifneq ($(filter config %config,$(MAKECMDGOALS)),)
                config-targets := 1
                ifneq ($(filter-out config %config,$(MAKECMDGOALS)),)
                        mixed-targets := 1
                endif
        endif
endif

ifeq ($(mixed-targets),1)
# ===========================================================================
# We're called with mixed targets (*config and build targets).
# Handle them one by one.

%:: FORCE
	$(Q)$(MAKE) -C $(srctree) KBUILD_SRC= $@

else
ifeq ($(config-targets),1)
# ===========================================================================
# *config targets only - make sure prerequisites are updated, and descend
# in scripts/kconfig to make the *config target

# Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
# KBUILD_DEFCONFIG may point out an alternative default configuration
# used for 'make defconfig'
include $(srctree)/arch/$(SRCARCH)/Makefile
export KBUILD_DEFCONFIG KBUILD_KCONFIG

config: scripts_basic outputmakefile FORCE
	$(Q)mkdir -p include/linux include/config
	$(Q)$(MAKE) $(build)=scripts/kconfig $@

%config: scripts_basic outputmakefile FORCE
	$(Q)mkdir -p include/linux include/config
	$(Q)$(MAKE) $(build)=scripts/kconfig $@

else
# ===========================================================================
# Build targets only - this includes vmlinux, arch specific targets, clean
# targets and others. In general all targets except *config targets.

ifeq ($(KBUILD_EXTMOD),)
# Additional helpers built in scripts/
# Carefully list dependencies so we do not try to build scripts twice
# in parallel
PHONY += scripts
scripts: scripts_basic include/config/auto.conf include/config/tristate.conf
	$(Q)$(MAKE) $(build)=$(@)

# Objects we will link into vmlinux / subdirs we need to visit
init-y		:= init/
drivers-y	:= drivers/ sound/ firmware/
net-y		:= net/
libs-y		:= lib/
core-y		:= usr/
endif # KBUILD_EXTMOD

ifeq ($(dot-config),1)
# Read in config
-include include/config/auto.conf

ifeq ($(KBUILD_EXTMOD),)
# Read in dependencies to all Kconfig* files, make sure to run
# oldconfig if changes are detected.
-include include/config/auto.conf.cmd

# To avoid any implicit rule to kick in, define an empty command
$(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;

# If .config is newer than include/config/auto.conf, someone tinkered
# with it and forgot to run make oldconfig.
# if auto.conf.cmd is missing then we are probably in a cleaned tree so
# we execute the config step to be sure to catch updated Kconfig files
include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
	$(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
else
# external modules needs include/generated/autoconf.h and include/config/auto.conf
# but do not care if they are up-to-date. Use auto.conf to trigger the test
PHONY += include/config/auto.conf

include/config/auto.conf:
	$(Q)test -e include/generated/autoconf.h -a -e $@ || (		\
	echo;								\
	echo "  ERROR: Kernel configuration is invalid.";		\
	echo "         include/generated/autoconf.h or $@ are missing.";\
	echo "         Run 'make oldconfig && make prepare' on kernel src to fix it.";	\
	echo;								\
	/bin/false)

endif # KBUILD_EXTMOD

else
# Dummy target needed, because used as prerequisite
include/config/auto.conf: ;
endif # $(dot-config)

# The all: target is the default when no target is given on the
# command line.
# This allow a user to issue only 'make' to build a kernel including modules
# Defaults to vmlinux, but the arch makefile usually adds further targets
all: vmlinux

ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS	+= -Os
else
KBUILD_CFLAGS	+= -O2
endif

include $(srctree)/arch/$(SRCARCH)/Makefile

ifneq ($(CONFIG_FRAME_WARN),0)
KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
endif

# Force gcc to behave correct even for buggy distributions
ifndef CONFIG_CC_STACKPROTECTOR
KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
endif

# This warning generated too much noise in a regular build.
# Use make W=1 to enable this warning (see scripts/Makefile.build)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)

ifdef CONFIG_FRAME_POINTER
KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
else
# Some targets (ARM with Thumb2, for example), can't be built with frame
# pointers.  For those, we don't have FUNCTION_TRACER automatically
# select FRAME_POINTER.  However, FUNCTION_TRACER adds -pg, and this is
# incompatible with -fomit-frame-pointer with current GCC, so we don't use
# -fomit-frame-pointer with FUNCTION_TRACER.
ifndef CONFIG_FUNCTION_TRACER
KBUILD_CFLAGS	+= -fomit-frame-pointer
endif
endif

ifdef CONFIG_DEBUG_INFO
KBUILD_CFLAGS	+= -g
KBUILD_AFLAGS	+= -gdwarf-2
endif

ifdef CONFIG_DEBUG_INFO_REDUCED
KBUILD_CFLAGS 	+= $(call cc-option, -femit-struct-debug-baseonly)
endif

ifdef CONFIG_FUNCTION_TRACER
KBUILD_CFLAGS	+= -pg
ifdef CONFIG_DYNAMIC_FTRACE
	ifdef CONFIG_HAVE_C_RECORDMCOUNT
		BUILD_C_RECORDMCOUNT := y
		export BUILD_C_RECORDMCOUNT
	endif
endif
endif

# We trigger additional mismatches with less inlining
ifdef CONFIG_DEBUG_SECTION_MISMATCH
KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
endif

# arch Makefile may override CC so keep this after arch Makefile is included
NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
CHECKFLAGS     += $(NOSTDINC_FLAGS)

# warn about C99 declaration after statement
KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)

# disable pointer signed / unsigned warnings in gcc 4.0
KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign)

# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS	+= $(call cc-option,-fno-strict-overflow)

# conserve stack if available
KBUILD_CFLAGS   += $(call cc-option,-fconserve-stack)

# use the deterministic mode of AR if available
KBUILD_ARFLAGS := $(call ar-option,D)

# check for 'asm goto'
ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC)), y)
	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
endif

# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
# But warn user when we do so
warn-assign = \
$(warning "WARNING: Appending $K$(1) ($(K$(1))) from $(origin K$(1)) to kernel $$(1)")

ifneq ($(KCPPFLAGS),)
        $(call warn-assign,CPPFLAGS)
        KBUILD_CPPFLAGS += $(KCPPFLAGS)
endif
ifneq ($(KAFLAGS),)
        $(call warn-assign,AFLAGS)
        KBUILD_AFLAGS += $(KAFLAGS)
endif
ifneq ($(KCFLAGS),)
        $(call warn-assign,CFLAGS)
        KBUILD_CFLAGS += $(KCFLAGS)
endif

# Use --build-id when available.
LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
			      $(call cc-ldoption, -Wl$(comma)--build-id,))
KBUILD_LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)

ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
LDFLAGS_vmlinux	+= $(call ld-option, -X,)
endif

# Default kernel image to build when no specific target is given.
# KBUILD_IMAGE may be overruled on the command line or
# set in the environment
# Also any assignments in arch/$(ARCH)/Makefile take precedence over
# this default value
export KBUILD_IMAGE ?= vmlinux

#
# INSTALL_PATH specifies where to place the updated kernel and system map
# images. Default is /boot, but you can set it to other values
export	INSTALL_PATH ?= /boot

#
# INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
# relocations required by build roots.  This is not defined in the
# makefile but the argument can be passed to make if needed.
#

MODLIB	= $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
export MODLIB

#
#  INSTALL_MOD_STRIP, if defined, will cause modules to be
#  stripped after they are installed.  If INSTALL_MOD_STRIP is '1', then
#  the default option --strip-debug will be used.  Otherwise,
#  INSTALL_MOD_STRIP value will be used as the options to the strip command.

ifdef INSTALL_MOD_STRIP
ifeq ($(INSTALL_MOD_STRIP),1)
mod_strip_cmd = $(STRIP) --strip-debug
else
mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
endif # INSTALL_MOD_STRIP=1
else
mod_strip_cmd = true
endif # INSTALL_MOD_STRIP
export mod_strip_cmd


ifeq ($(KBUILD_EXTMOD),)
core-y		+= kernel/ mm/ fs/ ipc/ security/ crypto/ block/

vmlinux-dirs	:= $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
		     $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
		     $(net-y) $(net-m) $(libs-y) $(libs-m)))

vmlinux-alldirs	:= $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
		     $(init-n) $(init-) \
		     $(core-n) $(core-) $(drivers-n) $(drivers-) \
		     $(net-n)  $(net-)  $(libs-n)    $(libs-))))

init-y		:= $(patsubst %/, %/built-in.o, $(init-y))
core-y		:= $(patsubst %/, %/built-in.o, $(core-y))
drivers-y	:= $(patsubst %/, %/built-in.o, $(drivers-y))
net-y		:= $(patsubst %/, %/built-in.o, $(net-y))
libs-y1		:= $(patsubst %/, %/lib.a, $(libs-y))
libs-y2		:= $(patsubst %/, %/built-in.o, $(libs-y))
libs-y		:= $(libs-y1) $(libs-y2)

# Build vmlinux
# ---------------------------------------------------------------------------
# vmlinux is built from the objects selected by $(vmlinux-init) and
# $(vmlinux-main). Most are built-in.o files from top-level directories
# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
# Ordering when linking is important, and $(vmlinux-init) must be first.
#
# vmlinux
#   ^
#   |
#   +-< $(vmlinux-init)
#   |   +--< init/version.o + more
#   |
#   +--< $(vmlinux-main)
#   |    +--< driver/built-in.o mm/built-in.o + more
#   |
#   +-< kallsyms.o (see description in CONFIG_KALLSYMS section)
#
# vmlinux version (uname -v) cannot be updated during normal
# descending-into-subdirs phase since we do not yet know if we need to
# update vmlinux.
# Therefore this step is delayed until just before final link of vmlinux -
# except in the kallsyms case where it is done just before adding the
# symbols to the kernel.
#
# System.map is generated to document addresses of all kernel symbols

vmlinux-init := $(head-y) $(init-y)
vmlinux-main := $(core-y) $(libs-y) $(drivers-y) $(net-y)
vmlinux-all  := $(vmlinux-init) $(vmlinux-main)
vmlinux-lds  := arch/$(SRCARCH)/kernel/vmlinux.lds
export KBUILD_VMLINUX_OBJS := $(vmlinux-all)

# Rule to link vmlinux - also used during CONFIG_KALLSYMS
# May be overridden by arch/$(ARCH)/Makefile
quiet_cmd_vmlinux__ ?= LD      $@
      cmd_vmlinux__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \
      -T $(vmlinux-lds) $(vmlinux-init)                          \
      --start-group $(vmlinux-main) --end-group                  \
      $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o FORCE ,$^)

# Generate new vmlinux version
quiet_cmd_vmlinux_version = GEN     .version
      cmd_vmlinux_version = set -e;                     \
	if [ ! -r .version ]; then			\
	  rm -f .version;				\
	  echo 1 >.version;				\
	else						\
	  mv .version .old_version;			\
	  expr 0$(cat .old_version) + 1 >.version;	\
	fi;						\
	$(MAKE) $(build)=init

# Generate System.map
quiet_cmd_sysmap = SYSMAP
      cmd_sysmap = $(CONFIG_SHELL) $(srctree)/scripts/mksysmap

# Link of vmlinux
# If CONFIG_KALLSYMS is set .version is already updated
# Generate System.map and verify that the content is consistent
# Use + in front of the vmlinux_version rule to silent warning with make -j2
# First command is ':' to allow us to use + in front of the rule
define rule_vmlinux__
	:
	$(if $(CONFIG_KALLSYMS),,+$(call cmd,vmlinux_version))

	$(call cmd,vmlinux__)
	$(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd

	$(Q)$(if $($(quiet)cmd_sysmap),                                      \
	  echo '  $($(quiet)cmd_sysmap)  System.map' &&)                     \
	$(cmd_sysmap) $@ System.map;                                         \
	if [ $? -ne 0 ]; then                                               \
		rm -f $@;                                                    \
		/bin/false;                                                  \
	fi;
	$(verify_kallsyms)
endef


ifdef CONFIG_KALLSYMS
# Generate section listing all symbols and add it into vmlinux $(kallsyms.o)
# It's a three stage process:
# o .tmp_vmlinux1 has all symbols and sections, but __kallsyms is
#   empty
#   Running kallsyms on that gives us .tmp_kallsyms1.o with
#   the right size - vmlinux version (uname -v) is updated during this step
# o .tmp_vmlinux2 now has a __kallsyms section of the right size,
#   but due to the added section, some addresses have shifted.
#   From here, we generate a correct .tmp_kallsyms2.o
# o The correct .tmp_kallsyms2.o is linked into the final vmlinux.
# o Verify that the System.map from vmlinux matches the map from
#   .tmp_vmlinux2, just in case we did not generate kallsyms correctly.
# o If 'make KALLSYMS_EXTRA_PASS=1" was used, do an extra pass using
#   .tmp_vmlinux3 and .tmp_kallsyms3.o.  This is only meant as a
#   temporary bypass to allow the kernel to be built while the
#   maintainers work out what went wrong with kallsyms.

last_kallsyms := 2

ifdef KALLSYMS_EXTRA_PASS
ifneq ($(KALLSYMS_EXTRA_PASS),0)
last_kallsyms := 3
endif
endif

kallsyms.o := .tmp_kallsyms$(last_kallsyms).o

define verify_kallsyms
	$(Q)$(if $($(quiet)cmd_sysmap),                                      \
	  echo '  $($(quiet)cmd_sysmap)  .tmp_System.map' &&)                \
	  $(cmd_sysmap) .tmp_vmlinux$(last_kallsyms) .tmp_System.map
	$(Q)cmp -s System.map .tmp_System.map ||                             \
		(echo Inconsistent kallsyms data;                            \
		 echo This is a bug - please report about it;                \
		 echo Try "make KALLSYMS_EXTRA_PASS=1" as a workaround;      \
		 rm .tmp_kallsyms* ; /bin/false )
endef

# Update vmlinux version before link
# Use + in front of this rule to silent warning about make -j1
# First command is ':' to allow us to use + in front of this rule
cmd_ksym_ld = $(cmd_vmlinux__)
define rule_ksym_ld
	: 
	+$(call cmd,vmlinux_version)
	$(call cmd,vmlinux__)
	$(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
endef

# Generate .S file with all kernel symbols
quiet_cmd_kallsyms = KSYM    $@
      cmd_kallsyms = $(NM) -n {1}lt; | $(KALLSYMS) \
                     $(if $(CONFIG_KALLSYMS_ALL),--all-symbols) > $@

.tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms3.o: %.o: %.S scripts FORCE
	$(call if_changed_dep,as_o_S)

.tmp_kallsyms%.S: .tmp_vmlinux% $(KALLSYMS)
	$(call cmd,kallsyms)

# .tmp_vmlinux1 must be complete except kallsyms, so update vmlinux version
.tmp_vmlinux1: $(vmlinux-lds) $(vmlinux-all) FORCE
	$(call if_changed_rule,ksym_ld)

.tmp_vmlinux2: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms1.o FORCE
	$(call if_changed,vmlinux__)

.tmp_vmlinux3: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms2.o FORCE
	$(call if_changed,vmlinux__)

# Needs to visit scripts/ before $(KALLSYMS) can be used.
$(KALLSYMS): scripts ;

# Generate some data for debugging strange kallsyms problems
debug_kallsyms: .tmp_map$(last_kallsyms)

.tmp_map%: .tmp_vmlinux% FORCE
	($(OBJDUMP) -h {1}lt; | $(AWK) '/^ +[0-9]/{print $4 " 0 " $2}'; $(NM) {1}lt;) | sort > $@

.tmp_map3: .tmp_map2

.tmp_map2: .tmp_map1

endif # ifdef CONFIG_KALLSYMS

# Do modpost on a prelinked vmlinux. The finally linked vmlinux has
# relevant sections renamed as per the linker script.
quiet_cmd_vmlinux-modpost = LD      $@
      cmd_vmlinux-modpost = $(LD) $(LDFLAGS) -r -o $@                          \
	 $(vmlinux-init) --start-group $(vmlinux-main) --end-group             \
	 $(filter-out $(vmlinux-init) $(vmlinux-main) FORCE ,$^)
define rule_vmlinux-modpost
	:
	+$(call cmd,vmlinux-modpost)
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $@
	$(Q)echo 'cmd_$@ := $(cmd_vmlinux-modpost)' > $(dot-target).cmd
endef

# vmlinux image - including updated kernel symbols
vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o $(kallsyms.o) FORCE
ifdef CONFIG_HEADERS_CHECK
	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
endif
ifdef CONFIG_SAMPLES
	$(Q)$(MAKE) $(build)=samples
endif
ifdef CONFIG_BUILD_DOCSRC
	$(Q)$(MAKE) $(build)=Documentation
endif
	$(call vmlinux-modpost)
	$(call if_changed_rule,vmlinux__)
	$(Q)rm -f .old_version

# build vmlinux.o first to catch section mismatch errors early
ifdef CONFIG_KALLSYMS
.tmp_vmlinux1: vmlinux.o
endif

modpost-init := $(filter-out init/built-in.o, $(vmlinux-init))
vmlinux.o: $(modpost-init) $(vmlinux-main) FORCE
	$(call if_changed_rule,vmlinux-modpost)

# The actual objects are generated when descending, 
# make sure no implicit rule kicks in
$(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;

# Handle descending into subdirectories listed in $(vmlinux-dirs)
# Preset locale variables to speed up the build process. Limit locale
# tweaks to this spot to avoid wrong language settings when running
# make menuconfig etc.
# Error messages still appears in the original language

PHONY += $(vmlinux-dirs)
$(vmlinux-dirs): prepare scripts
	$(Q)$(MAKE) $(build)=$@

# Store (new) KERNELRELASE string in include/config/kernel.release
include/config/kernel.release: include/config/auto.conf FORCE
	$(Q)rm -f $@
	$(Q)echo "$(KERNELVERSION)$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))" > $@


# Things we need to do before we recursively start building the kernel
# or the modules are listed in "prepare".
# A multi level approach is used. prepareN is processed before prepareN-1.
# archprepare is used in arch Makefiles and when processed asm symlink,
# version.h and scripts_basic is processed / created.

# Listed in dependency order
PHONY += prepare archprepare prepare0 prepare1 prepare2 prepare3

# prepare3 is used to check if we are building in a separate output directory,
# and if so do:
# 1) Check that make has not been executed in the kernel src $(srctree)
prepare3: include/config/kernel.release
ifneq ($(KBUILD_SRC),)
	@$(kecho) '  Using $(srctree) as source for kernel'
	$(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \
		echo "  $(srctree) is not clean, please run 'make mrproper'";\
		echo "  in the '$(srctree)' directory.";\
		/bin/false; \
	fi;
endif

# prepare2 creates a makefile if using a separate output directory
prepare2: prepare3 outputmakefile asm-generic

prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \
                   include/config/auto.conf
	$(cmd_crmodverdir)

archprepare: prepare1 scripts_basic

prepare0: archprepare FORCE
	$(Q)$(MAKE) $(build)=.

# All the preparing..
prepare: prepare0

# Generate some files
# ---------------------------------------------------------------------------

# KERNELRELEASE can change from a few different places, meaning version.h
# needs to be updated, so this check is forced on all builds

uts_len := 64
define filechk_utsrelease.h
	if [ `echo -n "$(KERNELRELEASE)" | wc -c ` -gt $(uts_len) ]; then \
	  echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2;    \
	  exit 1;                                                         \
	fi;                                                               \
	(echo \#define UTS_RELEASE \"$(KERNELRELEASE)\";)
endef

define filechk_version.h
	(echo \#define LINUX_VERSION_CODE $(shell                             \
	expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 0$(SUBLEVEL));    \
	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
endef

include/linux/version.h: $(srctree)/Makefile FORCE
	$(call filechk,version.h)

include/generated/utsrelease.h: include/config/kernel.release FORCE
	$(call filechk,utsrelease.h)

PHONY += headerdep
headerdep:
	$(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1 \
	$(srctree)/scripts/headerdep.pl -I$(srctree)/include

# ---------------------------------------------------------------------------

PHONY += depend dep
depend dep:
	@echo '*** Warning: make $@ is unnecessary now.'

# ---------------------------------------------------------------------------
# Firmware install
INSTALL_FW_PATH=$(INSTALL_MOD_PATH)/lib/firmware
export INSTALL_FW_PATH

PHONY += firmware_install
firmware_install: FORCE
	@mkdir -p $(objtree)/firmware
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_install

# ---------------------------------------------------------------------------
# Kernel headers

#Default location for installed headers
export INSTALL_HDR_PATH = $(objtree)/usr

hdr-inst := -rR -f $(srctree)/scripts/Makefile.headersinst obj

# If we do an all arch process set dst to asm-$(hdr-arch)
hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)

PHONY += __headers
__headers: include/linux/version.h scripts_basic asm-generic FORCE
	$(Q)$(MAKE) $(build)=scripts build_unifdef

PHONY += headers_install_all
headers_install_all:
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/headers.sh install

PHONY += headers_install
headers_install: __headers
	$(if $(wildcard $(srctree)/arch/$(hdr-arch)/include/asm/Kbuild),, \
	$(error Headers not exportable for the $(SRCARCH) architecture))
	$(Q)$(MAKE) $(hdr-inst)=include
	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/asm $(hdr-dst)

PHONY += headers_check_all
headers_check_all: headers_install_all
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/headers.sh check

PHONY += headers_check
headers_check: headers_install
	$(Q)$(MAKE) $(hdr-inst)=include HDRCHECK=1
	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/asm $(hdr-dst) HDRCHECK=1

# ---------------------------------------------------------------------------
# Modules

ifdef CONFIG_MODULES

# By default, build modules as well

all: modules

#	Build modules
#
#	A module can be listed more than once in obj-m resulting in
#	duplicate lines in modules.order files.  Those are removed
#	using awk while concatenating to the final file.

PHONY += modules
modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin
	$(Q)$(AWK) '!x[$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
	@$(kecho) '  Building modules, stage 2.';
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modbuild

modules.builtin: $(vmlinux-dirs:%=%/modules.builtin)
	$(Q)$(AWK) '!x[$0]++' $^ > $(objtree)/modules.builtin

%/modules.builtin: include/config/auto.conf
	$(Q)$(MAKE) $(modbuiltin)=$*


# Target to prepare building external modules
PHONY += modules_prepare
modules_prepare: prepare scripts

# Target to install modules
PHONY += modules_install
modules_install: _modinst_ _modinst_post

PHONY += _modinst_
_modinst_:
	@rm -rf $(MODLIB)/kernel
	@rm -f $(MODLIB)/source
	@mkdir -p $(MODLIB)/kernel
	@ln -s $(srctree) $(MODLIB)/source
	@if [ ! $(objtree) -ef  $(MODLIB)/build ]; then \
		rm -f $(MODLIB)/build ; \
		ln -s $(objtree) $(MODLIB)/build ; \
	fi
	@cp -f $(objtree)/modules.order $(MODLIB)/
	@cp -f $(objtree)/modules.builtin $(MODLIB)/
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst

# This depmod is only for convenience to give the initial
# boot a modules.dep even before / is mounted read-write.  However the
# boot script depmod is the master version.
PHONY += _modinst_post
_modinst_post: _modinst_
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modinst
	$(call cmd,depmod)

else # CONFIG_MODULES

# Modules not configured
# ---------------------------------------------------------------------------

modules modules_install: FORCE
	@echo
	@echo "The present kernel configuration has modules disabled."
	@echo "Type 'make config' and enable loadable module support."
	@echo "Then build a kernel with module support enabled."
	@echo
	@exit 1

endif # CONFIG_MODULES

###
# Cleaning is done on three levels.
# make clean     Delete most generated files
#                Leave enough to build external modules
# make mrproper  Delete the current configuration, and all generated files
# make distclean Remove editor backup files, patch leftover files and the like

# Directories & files removed with 'make clean'
CLEAN_DIRS  += $(MODVERDIR)
CLEAN_FILES +=	vmlinux System.map \
                .tmp_kallsyms* .tmp_version .tmp_vmlinux* .tmp_System.map

# Directories & files removed with 'make mrproper'
MRPROPER_DIRS  += include/config usr/include include/generated          \
                  arch/*/include/generated
MRPROPER_FILES += .config .config.old .version .old_version             \
                  include/linux/version.h                               \
		  Module.symvers tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS

# clean - Delete most, but leave enough to build external modules
#
clean: rm-dirs  := $(CLEAN_DIRS)
clean: rm-files := $(CLEAN_FILES)
clean-dirs      := $(addprefix _clean_, . $(vmlinux-alldirs) Documentation)

PHONY += $(clean-dirs) clean archclean
$(clean-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)

clean: archclean

# mrproper - Delete all generated files, including .config
#
mrproper: rm-dirs  := $(wildcard $(MRPROPER_DIRS))
mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
mrproper-dirs      := $(addprefix _mrproper_,Documentation/DocBook scripts)

PHONY += $(mrproper-dirs) mrproper archmrproper
$(mrproper-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)

mrproper: clean archmrproper $(mrproper-dirs)
	$(call cmd,rmdirs)
	$(call cmd,rmfiles)

# distclean
#
PHONY += distclean

distclean: mrproper
	@find $(srctree) $(RCS_FIND_IGNORE) \
		\( -name '*.orig' -o -name '*.rej' -o -name '*~' \
		-o -name '*.bak' -o -name '#*#' -o -name '.*.orig' \
		-o -name '.*.rej' \
		-o -name '*%' -o -name '.*.cmd' -o -name 'core' \) \
		-type f -print | xargs rm -f


# Packaging of the kernel to various formats
# ---------------------------------------------------------------------------
# rpm target kept for backward compatibility
package-dir	:= $(srctree)/scripts/package

%src-pkg: FORCE
	$(Q)$(MAKE) $(build)=$(package-dir) $@
%pkg: include/config/kernel.release FORCE
	$(Q)$(MAKE) $(build)=$(package-dir) $@
rpm: include/config/kernel.release FORCE
	$(Q)$(MAKE) $(build)=$(package-dir) $@


# Brief documentation of the typical targets used
# ---------------------------------------------------------------------------

boards := $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*_defconfig)
boards := $(notdir $(boards))
board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*/*_defconfig))
board-dirs := $(sort $(notdir $(board-dirs:/=)))

help:
	@echo  'Cleaning targets:'
	@echo  '  clean		  - Remove most generated files but keep the config and'
	@echo  '                    enough build support to build external modules'
	@echo  '  mrproper	  - Remove all generated files + config + various backup files'
	@echo  '  distclean	  - mrproper + remove editor backup and patch files'
	@echo  ''
	@echo  'Configuration targets:'
	@$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
	@echo  ''
	@echo  'Other generic targets:'
	@echo  '  all		  - Build all targets marked with [*]'
	@echo  '* vmlinux	  - Build the bare kernel'
	@echo  '* modules	  - Build all modules'
	@echo  '  modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
	@echo  '  firmware_install- Install all firmware to INSTALL_FW_PATH'
	@echo  '                    (default: $(INSTALL_MOD_PATH)/lib/firmware)'
	@echo  '  dir/            - Build all files in dir and below'
	@echo  '  dir/file.[oisS] - Build specified target only'
	@echo  '  dir/file.lst    - Build specified mixed source/assembly target only'
	@echo  '                    (requires a recent binutils and recent build (System.map))'
	@echo  '  dir/file.ko     - Build module including final link'
	@echo  '  modules_prepare - Set up for building external modules'
	@echo  '  tags/TAGS	  - Generate tags file for editors'
	@echo  '  cscope	  - Generate cscope index'
	@echo  '  gtags           - Generate GNU GLOBAL index'
	@echo  '  kernelrelease	  - Output the release version string'
	@echo  '  kernelversion	  - Output the version stored in Makefile'
	@echo  '  headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH'; \
	 echo  '                    (default: $(INSTALL_HDR_PATH))'; \
	 echo  ''
	@echo  'Static analysers'
	@echo  '  checkstack      - Generate a list of stack hogs'
	@echo  '  namespacecheck  - Name space analysis on compiled kernel'
	@echo  '  versioncheck    - Sanity check on version.h usage'
	@echo  '  includecheck    - Check for duplicate included header files'
	@echo  '  export_report   - List the usages of all exported symbols'
	@echo  '  headers_check   - Sanity check on exported headers'
	@echo  '  headerdep       - Detect inclusion cycles in headers'
	@$(MAKE) -f $(srctree)/scripts/Makefile.help checker-help
	@echo  ''
	@echo  'Kernel packaging:'
	@$(MAKE) $(build)=$(package-dir) help
	@echo  ''
	@echo  'Documentation targets:'
	@$(MAKE) -f $(srctree)/Documentation/DocBook/Makefile dochelp
	@echo  ''
	@echo  'Architecture specific targets ($(SRCARCH)):'
	@$(if $(archhelp),$(archhelp),\
		echo '  No architecture specific help defined for $(SRCARCH)')
	@echo  ''
	@$(if $(boards), \
		$(foreach b, $(boards), \
		printf "  %-24s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
		echo '')
	@$(if $(board-dirs), \
		$(foreach b, $(board-dirs), \
		printf "  %-16s - Show %s-specific targets\\n" help-$(b) $(b);) \
		printf "  %-16s - Show all of the above\\n" help-boards; \
		echo '')

	@echo  '  make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
	@echo  '  make V=2   [targets] 2 => give reason for rebuild of target'
	@echo  '  make O=dir [targets] Locate all output files in "dir", including .config'
	@echo  '  make C=1   [targets] Check all c source with $CHECK (sparse by default)'
	@echo  '  make C=2   [targets] Force check of all c source with $CHECK'
	@echo  '  make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
	@echo  '  make W=n   [targets] Enable extra gcc checks, n=1,2,3 where'
	@echo  '		1: warnings which may be relevant and do not occur too often'
	@echo  '		2: warnings which occur quite often but may still be relevant'
	@echo  '		3: more obscure warnings, can most likely be ignored'
	@echo  '		Multiple levels can be combined with W=12 or W=123'
	@echo  ''
	@echo  'Execute "make" or "make all" to build all targets marked with [*] '
	@echo  'For further info see the ./README file'


help-board-dirs := $(addprefix help-,$(board-dirs))

help-boards: $(help-board-dirs)

boards-per-dir = $(notdir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/$*/*_defconfig))

$(help-board-dirs): help-%:
	@echo  'Architecture specific targets ($(SRCARCH) $*):'
	@$(if $(boards-per-dir), \
		$(foreach b, $(boards-per-dir), \
		printf "  %-24s - Build for %s\\n" $*/$(b) $(subst _defconfig,,$(b));) \
		echo '')


# Documentation targets
# ---------------------------------------------------------------------------
%docs: scripts_basic FORCE
	$(Q)$(MAKE) $(build)=scripts build_docproc
	$(Q)$(MAKE) $(build)=Documentation/DocBook $@

else # KBUILD_EXTMOD

###
# External module support.
# When building external modules the kernel used as basis is considered
# read-only, and no consistency checks are made and the make
# system is not used on the basis kernel. If updates are required
# in the basis kernel ordinary make commands (without M=...) must
# be used.
#
# The following are the only valid targets when building external
# modules.
# make M=dir clean     Delete all automatically generated files
# make M=dir modules   Make all modules in specified dir
# make M=dir	       Same as 'make M=dir modules'
# make M=dir modules_install
#                      Install the modules built in the module directory
#                      Assumes install directory is already created

# We are always building modules
KBUILD_MODULES := 1
PHONY += crmodverdir
crmodverdir:
	$(cmd_crmodverdir)

PHONY += $(objtree)/Module.symvers
$(objtree)/Module.symvers:
	@test -e $(objtree)/Module.symvers || ( \
	echo; \
	echo "  WARNING: Symbol version dump $(objtree)/Module.symvers"; \
	echo "           is missing; modules will have no dependencies and modversions."; \
	echo )

module-dirs := $(addprefix _module_,$(KBUILD_EXTMOD))
PHONY += $(module-dirs) modules
$(module-dirs): crmodverdir $(objtree)/Module.symvers
	$(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)

modules: $(module-dirs)
	@$(kecho) '  Building modules, stage 2.';
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

PHONY += modules_install
modules_install: _emodinst_ _emodinst_post

install-dir := $(if $(INSTALL_MOD_DIR),$(INSTALL_MOD_DIR),extra)
PHONY += _emodinst_
_emodinst_:
	$(Q)mkdir -p $(MODLIB)/$(install-dir)
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst

PHONY += _emodinst_post
_emodinst_post: _emodinst_
	$(call cmd,depmod)

clean-dirs := $(addprefix _clean_,$(KBUILD_EXTMOD))

PHONY += $(clean-dirs) clean
$(clean-dirs):
	$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)

clean:	rm-dirs := $(MODVERDIR)
clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers

help:
	@echo  '  Building external modules.'
	@echo  '  Syntax: make -C path/to/kernel/src M=$PWD target'
	@echo  ''
	@echo  '  modules         - default target, build the module(s)'
	@echo  '  modules_install - install the module'
	@echo  '  clean           - remove generated files in module directory only'
	@echo  ''

# Dummies...
PHONY += prepare scripts
prepare: ;
scripts: ;
endif # KBUILD_EXTMOD

clean: $(clean-dirs)
	$(call cmd,rmdirs)
	$(call cmd,rmfiles)
	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
		\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
		-o -name '*.symtypes' -o -name 'modules.order' \
		-o -name modules.builtin -o -name '.tmp_*.o.*' \
		-o -name '*.gcno' \) -type f -print | xargs rm -f

# Generate tags for editors
# ---------------------------------------------------------------------------
quiet_cmd_tags = GEN     $@
      cmd_tags = $(CONFIG_SHELL) $(srctree)/scripts/tags.sh $@

tags TAGS cscope gtags: FORCE
	$(call cmd,tags)

# Scripts to check various things for consistency
# ---------------------------------------------------------------------------

PHONY += includecheck versioncheck coccicheck namespacecheck export_report

includecheck:
	find $(srctree)/* $(RCS_FIND_IGNORE) \
		-name '*.[hcS]' -type f -print | sort \
		| xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl

versioncheck:
	find $(srctree)/* $(RCS_FIND_IGNORE) \
		-name '*.[hcS]' -type f -print | sort \
		| xargs $(PERL) -w $(srctree)/scripts/checkversion.pl

coccicheck:
	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/$@

namespacecheck:
	$(PERL) $(srctree)/scripts/namespace.pl

export_report:
	$(PERL) $(srctree)/scripts/export_report.pl

endif #ifeq ($(config-targets),1)
endif #ifeq ($(mixed-targets),1)

PHONY += checkstack kernelrelease kernelversion

# UML needs a little special treatment here.  It wants to use the host
# toolchain, so needs $(SUBARCH) passed to checkstack.pl.  Everyone
# else wants $(ARCH), including people doing cross-builds, which means
# that $(SUBARCH) doesn't work here.
ifeq ($(ARCH), um)
CHECKSTACK_ARCH := $(SUBARCH)
else
CHECKSTACK_ARCH := $(ARCH)
endif
checkstack:
	$(OBJDUMP) -d vmlinux $(find . -name '*.ko') | \
	$(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)

kernelrelease:
	@echo "$(KERNELVERSION)$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"

kernelversion:
	@echo $(KERNELVERSION)

# Single targets
# ---------------------------------------------------------------------------
# Single targets are compatible with:
# - build with mixed source and output
# - build with separate output dir 'make O=...'
# - external modules
#
#  target-dir => where to store outputfile
#  build-dir  => directory in kernel source tree to use

ifeq ($(KBUILD_EXTMOD),)
        build-dir  = $(patsubst %/,%,$(dir $@))
        target-dir = $(dir $@)
else
        zap-slash=$(filter-out .,$(patsubst %/,%,$(dir $@)))
        build-dir  = $(KBUILD_EXTMOD)$(if $(zap-slash),/$(zap-slash))
        target-dir = $(if $(KBUILD_EXTMOD),$(dir {1}lt;),$(dir $@))
endif

%.s: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.i: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.o: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.lst: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.s: %.S prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.o: %.S prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.symtypes: %.c prepare scripts FORCE
	$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)

# Modules
/: prepare scripts FORCE
	$(cmd_crmodverdir)
	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
	$(build)=$(build-dir)
%/: prepare scripts FORCE
	$(cmd_crmodverdir)
	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
	$(build)=$(build-dir)
%.ko: prepare scripts FORCE
	$(cmd_crmodverdir)
	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
	$(build)=$(build-dir) $(@:.ko=.o)
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

# FIXME Should go into a make.lib or something 
# ===========================================================================

quiet_cmd_rmdirs = $(if $(wildcard $(rm-dirs)),CLEAN   $(wildcard $(rm-dirs)))
      cmd_rmdirs = rm -rf $(rm-dirs)

quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files)))
      cmd_rmfiles = rm -f $(rm-files)

# Run depmod only if we have System.map and depmod is executable
quiet_cmd_depmod = DEPMOD  $(KERNELRELEASE)
      cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
                   $(KERNELRELEASE)

# Create temporary dir for module support files
# clean it up only when building all modules
cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \
                  $(if $(KBUILD_MODULES),; rm -f $(MODVERDIR)/*)

a_flags = -Wp,-MD,$(depfile) $(KBUILD_AFLAGS) $(AFLAGS_KERNEL) \
	  $(KBUILD_AFLAGS_KERNEL)                              \
	  $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(KBUILD_CPPFLAGS) \
	  $(modkern_aflags) $(EXTRA_AFLAGS) $(AFLAGS_$(basetarget).o)

quiet_cmd_as_o_S = AS      $@
cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ {1}lt;

# read all saved command lines

targets := $(wildcard $(sort $(targets)))
cmd_files := $(wildcard .*.cmd $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))

ifneq ($(cmd_files),)
  $(cmd_files): ;	# Do not try to update included dependency files
  include $(cmd_files)
endif

# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=dir
# Usage:
# $(Q)$(MAKE) $(clean)=dir
clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj

endif	# skip-makefile

PHONY += FORCE
FORCE:

# Declare the contents of the .PHONY variable as phony.  We keep that
# information in a variable so we can use it in if_changed and friends.
.PHONY: $(PHONY)

第九节一个完整的例子

第十节怎么添加一个自己的驱动

第十一节顶层Makefile注释

第十二节关键变量、表达式和语法注释


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