linux编译

本文详细解析了Linux内核的编译流程,包括顶层编译文件的划分、目标文件的变化过程,以及如何生成最终启动的Linux内核。通过理解这些步骤,开发者可以更好地掌握内核编译的细节。

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顶层编译文件:linux/Makefile
x86顶层编译文件:linux/arch/x86/Makefile
x86启动编译文件:linux/arch/x86/boot/Makefile
x86启动压缩编译文件:linux/arch/x86/boot/compressed/Makefile


顶层编译文件将顶层目录linux下的文件夹分为以下几个部分:

Build的目标

涉及目录

备注

core  

user、kernel、mm、fs、ipc、security、crypto、block

核心

driver

drivers、sound、firmware

驱动

init

init

初始化

net

net

网络

lib

lib

编译过程中目标文件变化过程

序号

层次

备注

1

linux/vmlinux.o

Elf格式文件,由所有目标文件组成

2

linux/vmlinux

将1 根据vmlinux.lds链接而成的可执行文件

3

linux/arch/x86/boot/compressd/vmlinux.bin

将2中不必要的区段去除而成

4

linux/arch/x86/boot/compressd/vmlinux.bin.gz

将3压缩而成

5

linux/arch/x86/boot/compressd/vmlinux

将一个解压程序与4结合成一个自解压文件

6

linux/arch/x86/boot/vmlinux.bin

将5中不必要的区段去除,还是一个自解压的内核

7

linux/arch/x86/boot/bzImage

将setup.bin和6连接而成,这是最终启动的linux内核

# 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-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
在http://lxr.linux.no/linux+v3.3.6/arch/x86/Makefile中:
head-y := arch/x86/kernel/head_$(BITS).o
head-y += arch/x86/kernel/head$(BITS).o
head-y += arch/x86/kernel/head.o
head-y += arch/x86/kernel/init_task.o
在arch/x86/kernel目录下存在一些head开头的汇编或c语言源代码的。其中BITS指出是32位还是64位。
head.c,head32.c,head64.c,head_32.S,head_64.S,init_task.c
(在顶层makefile)而其它子目标都是指向具体的根目录下的子目录了:
init-y		:= init/
drivers-y	:= drivers/ sound/ firmware/
net-y		:= net/
libs-y		:= lib/
core-y		:= usr/
在http://lxr.linux.no/linux+v3.3.6/arch/x86/boot/Makefile中:
bzImage: $(obj)/setup.bin $(obj)/vmlinux.bin $(obj)/tools/build FORCE
说明bzImage是依赖于setup.bin vmlinux.bin 和tools的
最终如上表7中所说。











顶层makefile中
all: vmlinux
而 vmlinux定义为:
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)#执行cmd_vmlinux-modpost检查模块
$(call if_changed_rule,vmlinux__)#执行rule_vmlinux__,生成 vmlinux 校验 vmlinux
$(Q)rm -f .old_version#去除区段.old_version


 
ifeq ($(KBUILD_SRC),)                                                        【1】
     ifdef O                                                                 【2】      
           ifeq ("$(origin O)", "command line")                              【3】
                  KBUILD_OUTPUT := $(O)
           endif
     endif
     ...略
     ifneq ($(KBUILD_OUTPUT),)                                               【4】
           ...略
           .PHONY: $(MAKECMDGOALS)
           $(filter-out _all,$(MAKECMDGOALS)) _all:                          【5】
                  $(if $(KBUILD_VERBOSE:1=),@)$(MAKE) -C $(KBUILD_OUTPUT)        \
                  KBUILD_SRC=$(CURDIR)        KBUILD_VERBOSE=$(KBUILD_VERBOSE) \
                  KBUILD_CHECK=$(KBUILD_CHECK) KBUILD_CHECK="$(KBUILD_EXTMOD)"  \
                  -f $(CURDIR)/Makefile $@   
            skip-makefile := 1
    endif # ifneq ($(KBUILD_OUTPUT),)
endif # ifeq ($(KBUILD_SRC),) 
ifeq ($(skip-makefile),)                                                     【6】这个if包含了剩余的所有代码,很大的if
         MakeFile的其它部分
endif  # skip-makefile                                                       【7】

//////////////////////////////////////////////////////////////////////////////

一进本makefile文件,KBUILD_SRC是空的,所以进入if【1】,

如果O被定义了,并且来自命令行,KBUILD_OUTPUT【输出目录】就赋值为O

此时【4】KBUILD_OUTPUT不为空,所以进入此if

然后为另一个make设置命令行参数KBUILD_SRC,KBUILD_VERBOSE,KBUILD_CHECK,KBUILD_CHECK等,

激活另一个make过程

假设我们在命令行用O定义了输出目录的话,第一遍流程就是激活另一个make

在【6】处,因为skip-makefile := 1不等于空,(如果上面的激活了另一个make)则后续的会被跳过

那第二遍进来(被【5】激活)make,它有4个命令行变量KBUILD_SRC,KBUILD_VERBOSE,KBUILD_CHECK,KBUILD_CHECK

再次进入makefile,发现KBUILD_SRC不是空的,就跳过上面【1】开始的过程了

直接来到【6】发现此处的if是成立的,所以进入它。

//////////////////////////////////////////////////////////////////////////////

整个makefile的目标:

配置目标(configuration targets) menuconfig, defconfig ->产生两个文件->.config和.config.cmd

构建目标(build targerts)all, vmlinux,modules->makefile在这些目标里会用到上面产生的两个配置文件

维护目标(Maintenance targets) clean



make支持同时执行多个目标, 因为配置目标和构建目标是两个过程,所以可以make  oldconfig all

和.config无关的目标,如clean proper等

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


config-targets := 0   这个值表明此次make是否有配置目标
dot-config     := 1   是否有构建目标
mixed-targets  := 0   是不是两者都有





========================================================================================

 
ifeq ($(mixed-targets),1)                                                       【1】
         #mixed-targets是1的时候,混合目标,根据百分号匹配来处理所有目标
       %:: FORCE
                 $(Q)$(MAKE) -C $(srctree) KBUILD_SRC=$@
 
else                                                                            【1.else】
         #如果mixed-targets不是1的时候,非混合目标
         ifeq($(config-targets),1)                                              【2】
         '        #如果只有config-targets目标,即配置目标,目标里有个百分号,会匹配多个 *config
         '        include$(srctree)/arch/$(SRCARCH)/Makefile                 
         '        export KBUILD_DEFCONFIG KBUILD_KCONFIG      
         '        config: scripts_basic outputmakefileFORCE
         '                  $(Q)mkdir -p include/linuxinclude/config
         '                  $(Q)$(MAKE) $(build)=scripts/kconfig$@
         '        %config: scripts_basic outputmakefileFORCE
         '                  $(Q)mkdir -p include/linuxinclude/config
         '                  $(Q)$(MAKE)$(build)=scripts/kconfig $@
         else                                                                    【2.else】
         '   #Build targets only - this includes vmlinux, arch specific targets, clean
         '        #targets and others. In general all targets except *config targets.
         '        # 只有构建目标build
         '        # 定义init-y,net-y,libs-y,core-y...等列表
         '        ...
         '       ifeq($(dot-config),1)                                            【3】
         '                  -includeinclude/config/auto.conf
         '                  -includeinclude/config/auto.conf.cmd
         '                  $(KCONFIG_CONFIG)include/config/auto.conf.cmd: ;
         '                  include/config/%.conf:$(KCONFIG_CONFIG) include/config/auto.conf.cmd
         '                           $(Q)$(MAKE) -f$(srctree)/Makefile silentoldconfig
         '        else                                                            【3.else】
         '                  include/config/auto.conf: 
         '        endif# $(dot-config)                                            【3.end】
         '        include$(srctree)/arch/$(ARCH)/Makefile
         '        ...其它部分 ...
       endif #ifeq ($(config-targets),1)                                          【2.end】 
endif #ifeq ($(mixed-targets),1)                                                  【1.end】       

 

 

 

 

 

 

 
 VERSION = 3
PATCHLEVEL = 3
SUBLEVEL = 3
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 ...";
# 不会隐含规则(r),不打印"Entering directory ..."字样
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









#预定义(自动变量)                      含义
#	*              不包含扩展名的目标文件名称。
#	+              所有的依赖文件,以空格分开,并以出现的先后为序,可能包含重复的依赖文件。
#	<              第一个依赖文件的名称。
#	?              所有的依赖文件,以空格分开,这些依赖文件的修改日期比目标的创建日期晚。
#	@              目标的完整名称。
#	^              所有的依赖文件,以空格分开,不包含重复的依赖文件。
#	%              如果目标是归档成员,则该变量表示目标的归档成员名称。例如,如果目标名称
#	              为 mytarget.so(image.o),则 $@ 为 mytarget.so,而 $% 为 image.o。



#=,等号,递归解析;而:=是不递归解析;?=是如果没定义则使用默认值

#Makefile是支持函数的,调用方法是$(fuc param1,param2,..)或${fuc param1,param2,..}
#常见函数有$(subst ,,)$(patsubst ,,)$(strip )$(findstring ,)$(filter ,)$(filter-out ,)
#$(sort )$(word ,)等等。。

#下面的origin也是一个函数,origin 函数的作用是告诉你变量是哪里来的,其出生状况如何,
#他并不改变变量。常见返回值:"undefined";"default"(默认的定义如CC);"environment"
#"file";"command line";"override"; "automatic"等等
#这句话是判断V变量的来源是不是"ommand line"命令行,如果是,则给KBUILD_VERBOSE
#赋值.KBUILD_VERBOSE的作用就是是否打印详细信息,后面还会影响另外一个宏:$(Q)。

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.
# make C=1时,仅仅检查编译器需要重新编译的文件,=2时检查所有文件。
# SPARSE checking,是linux内核源代码检查工具,用于检查代码中可能的编码错误



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

# M=dir指定外部模块目录
# 如果SUBDIRS定义了,则在这里先给KBUILD_EXTMOD变量设定了一个默认值
# 然后,如果命令行定义了M,则用M覆盖默认值
# 那SUBDIRS=$PWD中的$PWD被当成了默认值了
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支持将【输出文件】放到一个单独的目录中,可通过两种方式定位【输出文件】
# 这两种方法都要求【工作目录】必须是【内核代码根目录】
# 1)命令行形式:   make O=输出文件目录
# 2) 设置环境变量: export KBUILD_OUTPUT=输出文件目录
# 方法1优先于2

# 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)
# 在obj目录中调用make时,KBUILD_SRC 会被设置,KBUILD_SRC目前不是为了给一般用户使用

# 下面这句是判断KBUILD_SRC是否为空
ifeq ($(KBUILD_SRC),)

# OK, Make called in directory where kernel src resides
# Do we want to locate output files in a separate directory?
#如果KBUILD_SRC是空的,则KBUILD_OUTPUT=命令行指定的输出文件路径
ifeq ("$(origin O)", "command line")
  KBUILD_OUTPUT := $(O)
endif
#下面这个变量应该是gcc检查
ifeq ("$(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
#默认的总目标
PHONY := _all
_all:

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

ifneq ($(KBUILD_OUTPUT),)
#如果输出目录不为空的话,将输出目录保存起来,检查输出目录是否存在,
#shell函数是执行shell命令,make会把命令结果中回车换行替换成空格返回回来
# 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函数的语法是:$(if <condition>,<then-part>) 或是 $(if <condition>,<then-part>,<else-part>)。
#下面这句的意思是如果KBUILD_OUTPUT不为空(上面那句检查成功)则执行,,中间的(什么也不做),else
#则报错error output...

$(if $(KBUILD_OUTPUT),, \
     $(error output directory "$(saved-output)" does not exist))

PHONY += $(MAKECMDGOALS) sub-make
#反过滤函数,去掉目标串中所有模式匹配的子串,剩下的返回 
$(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
	$(Q)@:

#$(if $(KBUILD_VERBOSE:1=),@)一行相当于调用$(if $(patsubst %1,%,$(KBUILD_VERBOSE)),@)
#即当变量==1时,返回@符号(shell不输出)
#这一行激活了另外一个make
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
# 是否编译外部模块
PHONY += all
ifeq ($(KBUILD_EXTMOD),)
_all: all
else
_all: modules
endif
#如果KBUILD_SRC存在,则将它赋值给srctree,否则将CURDIR赋值给srctree
srctree		:= $(if $(KBUILD_SRC),$(KBUILD_SRC),$(CURDIR))
#CURDIR为make默认环境变量

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.
# sed -e s/xxxx/yyyy/  表示替换,将x替换为y
# SUBARCH最终会得到一个当前系统架构信息如 i386 sparc64..等
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
# 交叉编译,make时需要手动地设置arch



#导出宿主机的架构,给子make用
export KBUILD_BUILDHOST := $(SUBARCH)
#'?='条件赋值,如果前面没有赋值的话,则在这里赋值
# ARCH是目标架构
ARCH		?= $(SUBARCH)
# 交叉编译器路径
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
#导出生成的配置文件名,条件赋值
KCONFIG_CONFIG	?= .config
export KCONFIG_CONFIG

# SHELL used by kbuild
# 测试shell是否可执行
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.
# 非空返回1
ifeq ($(MAKECMDGOALS),modules)
  KBUILD_BUILTIN := $(if $(CONFIG_MODVERSIONS),1)
endif

#	If we have "make <whatever> 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
#导出相关变量
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 $@ $<
#
# 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 ($(filter s% -s%,$(MAKEFLAGS)),)
  quiet=silent_
endif
#导出是否打印的环境变量
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).
# 包含文件进来,原样放到include出现的位置
$(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		#sparse检查

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.
# firstword 返回第一个字符。
# 
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.
# 在指定目录生成一个makefile
# KBUILD_SRC为空,所以不会执行
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).

# 和.config无关的目标,如,clean,mrproper,distclean,header_install,kernelrelease,kernelversion等
no-dot-config-targets := clean mrproper distclean \
			 cscope gtags TAGS tags help %docs check% coccicheck \
			 include/linux/version.h headers_% archheaders \
			 kernelversion %src-pkg
#和.config相关目标:.config自身,使用.config的目标:all,vmlinux,modules,zimage等
config-targets := 0	#
mixed-targets  := 0
dot-config     := 1



ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)	#目标中有no-dot-config-targets
	ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)	#且只有no-dot-config-targets
		dot-config := 0	
	endif
endif

ifeq ($(KBUILD_EXTMOD),)
        ifneq ($(filter config %config,$(MAKECMDGOALS)),)	#rhf j gik e menucomfig,xcomfig等
                config-targets := 1
                ifneq ($(filter-out config %config,$(MAKECMDGOALS)),)#除%config外,不=空,说明有其它目标时
                        mixed-targets := 1
                endif
        endif
endif

ifeq ($(mixed-targets),1)
# ===========================================================================
# We're called with mixed targets (*config and build targets).
# Handle them one by one.
# 这里有一个双冒号规则,%代码匹配任何,srctree是内核代码目录KBUILD_SRC为空
# '$@'代表所有参数,如命令行是 make aaa bbb,那么就会解释成:
# 	$(Q)$(MAKE) -C $(srctree) KBUILD_SRC= aaa
#	$(Q)$(MAKE) -C $(srctree) KBUILD_SRC= bbb
# 因为aaa bbb 是本层make的两个目标,而匹配上了百分号%(任意)
# 这种操作等于make aaa && make bbb



%:: 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'

# 将平台相关的makefile包含进来,以用其中的KBUILD_DEFCONFIG的值

include $(srctree)/arch/$(SRCARCH)/Makefile
# 将相关变量导出,以备子make用

export KBUILD_DEFCONFIG KBUILD_KCONFIG
#以下是两个目标,一个是config,另外一个是%config
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)
#如果.config已经配置,则会生成auto.conf,包含进来
# 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.
#如果变量是空,则包含文件进来. ‘-’表示让make忽略不能读进来的include文件,继续执行
-include include/config/auto.conf.cmd

# To avoid any implicit rule to kick in, define an empty command
#定义了一个规则,没有依赖和命令,它是空的
$(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

#定义一个目标,依赖文件是vmlinux,这个是默认目标
all: vmlinux
#只检查变量是否被赋值,然后进行相应处理
ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS	+= -Os
else
KBUILD_CFLAGS	+= -O2
endif

#包含一个架构makefile
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

# 给core-y列表追加其它目录
ifeq ($(KBUILD_EXTMOD),)
core-y		+= kernel/ mm/ fs/ ipc/ security/ crypto/ block/

# 分两步,外面是替换函数将'%/'替换成'%',filter函数将串中符合模式'%/'的子串返回
# 然后去除以/结尾的串中的/符号,最后全部是不以/结尾的
# $(patsubst <pattern>, <replacement>, <text>),若pattern中有%,而replacement中也有%
# 那么replacement中的%表示pattern中匹配的%内容
vmlinux-dirs	:= $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
		     $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
		     $(net-y) $(net-m) $(libs-y) $(libs-m)))
#分两步,外面是去重复、返回升序排序后的两个列表,里面是与上面一样
vmlinux-alldirs	:= $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
		     $(init-n) $(init-) \
		     $(core-n) $(core-) $(drivers-n) $(drivers-) \
		     $(net-n)  $(net-)  $(libs-n)    $(libs-))))
#到这里init-y等值没变,上面的操作只是返回改变后的值,原变量值没变。
#下面,给每个列表重新赋值,各列表变成相应的对象目标(顶层目录)
#把这些目标连接到一起,就构成了vmlinux-main
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
# System.map 内容是记录所有内核符号的地址
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

#定义一个规则
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__)				#(call cmd,bbbb)展开后就是cmd_bbbb
	$(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
endef

# Generate .S file with all kernel symbols
quiet_cmd_kallsyms = KSYM    $@
      cmd_kallsyms = $(NM) -n $< | $(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 $< | $(AWK) '/^ +[0-9]/{print $$4 " 0 " $$2}'; $(NM) $<) | 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: archheaders 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 += archheaders
archheaders:

PHONY += __headers
__headers: include/linux/version.h scripts_basic asm-generic archheaders 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 $<),$(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 $@ $<

# 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)






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