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。
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 |
库 |
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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