分析一下在命令行输入了make menuconfig 之后,到底发生了哪些事情：
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- linux_2.6.30.4/Makefile
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#scripts/Kbuild.include 文件L144包含build
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#L144 build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
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184 $(srctree)/scripts/Kbuild.include: ;
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185 include $(srctree)/scripts/Kbuild.include
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245
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246 PHONY += scripts_basic
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247 scripts_basic:
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248 $(Q)$(MAKE) $(build)=scripts/basic
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#make -f scripts/Makefile.build obj=scripts/basic
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249
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250 scripts/basic/%: scripts_basic ;
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251
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252 PHONY += outputmakefile
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253 outputmakefile:
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#此处KBUILD_SRC为空,ifneq条件不成立,所以outputmakefile不作任何操作
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254 ifneq ($(KBUILD_SRC),)
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255 $(Q)ln -fsn $(srctree) source
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256 $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile \
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257 $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
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258 endif
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259
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260
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261 no-dot-config-targets := clean mrproper distclean \
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262 cscope TAGS tags help %docs check% \
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263 include/linux/version.h headers_% \
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264 kernelrelease kernelversion
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265
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266 config-targets := 0
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267 mixed-targets := 0
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268 dot-config := 1
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269 #因为MAKECMDGOALS=menuconfig,此处filter结果为空,ifneq条件不成立，所以dot-config:=1
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270 ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
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271 ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
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272 dot-config := 0
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273 endif
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274 endif
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275 #KBUILD_EXTMOD为空,ifeq条件成立进入，filter执行结果为menuconfig不为空，ifneq条件不成立config-targets=1,mixed-targets=0
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276 ifeq ($(KBUILD_EXTMOD),)
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277 ifneq ($(filter config %config,$(MAKECMDGOALS)),)
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278 config-targets := 1
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279 ifneq ($(filter-out config %config,$(MAKECMDGOALS)),)
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280 mixed-targets := 1
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281 endif
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282 endif
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283 endif
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284 #config-targets=1 mixed-targets=0 dot-config=1 #所以执行L291
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285 ifeq ($(mixed-targets),1)
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286
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287 %:: FORCE
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288 $(Q)$(MAKE) -C $(srctree) KBUILD_SRC= $@
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289
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290 else
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291 ifeq ($(config-targets),1)
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292 # 将 ./arch/arm/Makefile 包含进来
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293 include $(srctree)/arch/$(SRCARCH)/Makefile
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294 export KBUILD_DEFCONFIG KBUILD_KCONFIG
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295
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296 config: scripts_basic outputmakefile FORCE
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297 $(Q)mkdir -p include/linux include/config
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298 $(Q)$(MAKE) $(build)=scripts/kconfig $@
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299 #%config匹配了menuconfig,不仔细看还真看不出来
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300 %config: scripts_basic outputmakefile FORCE
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301 $(Q)mkdir -p include/linux include/config
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302 $(Q)$(MAKE) $(build)=scripts/kconfig $@
- #由scripts/Kbuild.include的build知，L302:make -f scripts/Makefile.build obj=scripts/kconfig menuconfig
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所以执行了 make menuconfig 之后，会执行以下五步：
1. 执行 scripts_basic 依赖：( make -f scripts/Makefile.build obj=scripts/basic )
2. 执行 outputmakefile 依赖：(KBUILD_SRC为空，所以不做任何操作 )
3. FORCE
4. mkdir -p include/linux include/config :(创建文件夹)
5. $(MAKE) $(build)=scripts/kconfig $@ (make -f scripts/Makefile.build obj=scripts/kconfig menuconfig)
所以最重要的是第1步和第5步，下面详细分析一下这两步
1.执行 scripts_basic 依赖：( make -f scripts/Makefile.build obj=scripts/basic )
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- scripts/Makefile.build
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1 #传参数obj=scripts/basic
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2 src := $(obj)
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4 PHONY := __build
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5 __build:
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27 -include include/config/auto.conf
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28
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29 include scripts/Kbuild.include
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32 #src=scripts/basic, filter判断$(src)是不是以/开头，绝对路径，不是绝对路径则加$(srctree)/$(src)
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33 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
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#wildcard判断绝对路径$(srctree)/script/basic目录下是否有Kbuild文件，如果没有则为$(srctree)/script/basic/Makefile
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34 kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
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#将$(srctree)/script/basic/Makefile加入，这个Makefile中有menuconfig的依赖关系
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35 include $(kbuild-file)
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36
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#在$(srctree)/script/basic/Makefile中定义了，hostprogs-y
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51 ifneq ($(hostprogs-y)$(hostprogs-m),)
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52 include scripts/Makefile.host
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53 endif
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# 有两个__build，用下面这个最新的__build
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# KBUILD_BUILTIN=1, KBUILT_MODULES=null, 所以__build=(builtin-target lib-target extra-y modorder-target subdir-ym always)
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# __build=(modorder-target always)
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# always=scripts/basic/fixdep scripts/basic/docproc scripts/basic/hash
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# modorder-target=scripts/basic/modules.order
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77 __build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
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78 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
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79 $(subdir-ym) $(always)
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80 @:
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# $(modorder-target)在Makefile.build中
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# $(modorder-target): $(subdir-ym) FORCE
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# $(Q)(cat /dev/null; $(modorder-cmds)) > $@
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# 没干什么实事
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# 所以 scripts/basic 就是在scripts/basic/Makefile作用下编译生成docproc fixdep hash 这三个elf文件
- 81
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- scripts/kconfig/Makefile
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#没有定义KBUILD_KCONFIG,所以Kconfig=arch/arm/Kconfig
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4 ifdef KBUILD_KCONFIG
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5 Kconfig := $(KBUILD_KCONFIG)
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6 else
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7 Kconfig := arch/$(SRCARCH)/Kconfig
- 8 endif
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# 先去生成mconf这个elf文件(看到的图形界面就是这个东东)，然后调用scripts/kconfig/mconf arch/arm/Kconfig
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# 这样就可以看到配置选项
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16 menuconfig: $(obj)/mconf
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17 $< $(Kconfig)
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86 check-lxdialog := $(srctree)/$(src)/lxdialog/check-lxdialog.sh
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87
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88 HOST_EXTRACFLAGS = $(shell $(CONFIG_SHELL) $(check-lxdialog) -ccflags)
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89 HOST_LOADLIBES = $(shell $(CONFIG_SHELL) $(check-lxdialog) -ldflags $(HOSTCC))
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90
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91 HOST_EXTRACFLAGS += -DLOCALE
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92
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93
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94
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95 lxdialog := lxdialog/checklist.o lxdialog/util.o lxdialog/inputbox.o
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96 lxdialog += lxdialog/textbox.o lxdialog/yesno.o lxdialog/menubox.o
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97 #没有看出mconf和mconf-objs是通过什么关系对应起来的，通过打印mconf的生成过程，可以看出mconf就是mconf-objs
- #gcc -o scripts/kconfig/mconf scripts/kconfig/mconf.o scripts/kconfig/zconf.tab.o scripts/kconfig/lxdialog/checklist.o scripts/kconfig/lxdialog/util.o scripts/kconfig/lxdialog/inputbox.o scripts/kconfig/lxdialog/textbox.o scripts/kconfig/lxdialog/yesno.o scripts/kconfig/lxdialog/menubox.o -lncurses
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99 mconf-objs := mconf.o zconf.tab.o $(lxdialog)
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101
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102 hostprogs-y := conf qconf gconf kxgettext
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103
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104 ifeq ($(MAKECMDGOALS),menuconfig)
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105 hostprogs-y += mconf
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106 endif
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130 PHONY += $(obj)/dochecklxdialog
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131 $(addprefix $(obj)/,$(lxdialog)): $(obj)/dochecklxdialog
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132 $(obj)/dochecklxdialog:
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133 $(Q)$(CONFIG_SHELL) $(check-lxdialog) -check $(HOSTCC) $(HOST_EXTRACFLAGS) $(HOST_LOADLIBES)
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134
- 135 always := dochecklxdialog
写到快吐了！！！！