Linux内核---6.make menuconfig 流程分析

分析一下在命令行输入了make menuconfig 之后,到底发生了哪些事情：

点击(此处)折叠或打开

1. linux_2.6.30.4/Makefile
2. #scripts/Kbuild.include 文件L144包含build
   
3.         #L144 build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
   
4.    184    $(srctree)/scripts/Kbuild.include: ;
   
5.    185    include $(srctree)/scripts/Kbuild.include
   
6.            
   
7.    245    
   
8.    246    PHONY += scripts_basic
   
9.    247    scripts_basic:
   
10.    248        $(Q)$(MAKE) $(build)=scripts/basic
    
11.            #make -f scripts/Makefile.build obj=scripts/basic
    
12.    249    
    
13.    250    scripts/basic/%: scripts_basic ;
    
14.    251    
    
15.    252    PHONY += outputmakefile
    
16.    253    outputmakefile:
    
17.            #此处KBUILD_SRC为空,ifneq条件不成立,所以outputmakefile不作任何操作
    
18.    254    ifneq ($(KBUILD_SRC),)
    
19.    255        $(Q)ln -fsn $(srctree) source
    
20.    256        $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile \
    
21.    257         $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
    
22.    258    endif
    
23.    259    
    
24.    260    
    
25.    261    no-dot-config-targets := clean mrproper distclean \
    
26.    262                 cscope TAGS tags help %docs check% \
    
27.    263                 include/linux/version.h headers_% \
    
28.    264                 kernelrelease kernelversion
    
29.    265    
    
30.    266    config-targets := 0
    
31.    267    mixed-targets := 0
    
32.    268    dot-config := 1
    
33.    269 #因为MAKECMDGOALS=menuconfig,此处filter结果为空,ifneq条件不成立，所以dot-config:=1
    
34.    270    ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
    
35.    271        ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
    
36.    272            dot-config := 0
    
37.    273        endif
    
38.    274    endif
    
39.    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    
    
40.    276    ifeq ($(KBUILD_EXTMOD),)
    
41.    277     ifneq ($(filter config %config,$(MAKECMDGOALS)),)
    
42.    278     config-targets := 1
    
43.    279     ifneq ($(filter-out config %config,$(MAKECMDGOALS)),)
    
44.    280     mixed-targets := 1
    
45.    281     endif
    
46.    282     endif
    
47.    283    endif
    
48.    284 #config-targets=1 mixed-targets=0 dot-config=1    #所以执行L291
    
49.    285    ifeq ($(mixed-targets),1)
    
50.    286    
    
51.    287    %:: FORCE
    
52.    288        $(Q)$(MAKE) -C $(srctree) KBUILD_SRC= $@
    
53.    289    
    
54.    290    else
    
55.    291    ifeq ($(config-targets),1)
    
56.    292    # 将 ./arch/arm/Makefile 包含进来
    
57.    293    include $(srctree)/arch/$(SRCARCH)/Makefile
    
58.    294    export KBUILD_DEFCONFIG KBUILD_KCONFIG
    
59.    295    
    
60.    296    config: scripts_basic outputmakefile FORCE
    
61.    297        $(Q)mkdir -p include/linux include/config
    
62.    298        $(Q)$(MAKE) $(build)=scripts/kconfig $@
    
63.    299    #%config匹配了menuconfig,不仔细看还真看不出来
    
64.    300    %config: scripts_basic outputmakefile FORCE
    
65.    301        $(Q)mkdir -p include/linux include/config
    
66.    302        $(Q)$(MAKE) $(build)=scripts/kconfig $@
    
67. #由scripts/Kbuild.include的build知，L302:make -f scripts/Makefile.build obj=scripts/kconfig menuconfig
68. 
    

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 )

点击(此处)折叠或打开

1. scripts/Makefile.build
2.      1    #传参数obj=scripts/basic
   
3.      2    src := $(obj)
   
4.      4    PHONY := __build
   
5.      5    __build:
   
6.     27    -include include/config/auto.conf
   
7.     28    
   
8.     29    include scripts/Kbuild.include
   
9.     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)    
   
10.     33    kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
    
11.         #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
    
12.     34    kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
    
13.         #将$(srctree)/script/basic/Makefile加入，这个Makefile中有menuconfig的依赖关系
    
14.     35    include $(kbuild-file)
    
15.     36
    
16.         #在$(srctree)/script/basic/Makefile中定义了，hostprogs-y
    
17.     51    ifneq ($(hostprogs-y)$(hostprogs-m),)
    
18.     52    include scripts/Makefile.host
    
19.     53    endif
    
20. 
    
21.         # 有两个__build，用下面这个最新的__build
    
22.         # KBUILD_BUILTIN=1, KBUILT_MODULES=null, 所以__build=(builtin-target lib-target extra-y modorder-target subdir-ym always)
    
23.         # __build=(modorder-target always)
    
24.         # always=scripts/basic/fixdep scripts/basic/docproc scripts/basic/hash
    
25.         # modorder-target=scripts/basic/modules.order
    
26.     77    __build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
    
27.     78         $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
    
28.     79         $(subdir-ym) $(always)
    
29.     80        @:
    
30.         # $(modorder-target)在Makefile.build中
    
31.         # $(modorder-target): $(subdir-ym) FORCE
    
32.         #     $(Q)(cat /dev/null; $(modorder-cmds)) > $@
    
33.         # 没干什么实事
    
34.         # 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
    
35.     81

5.执行$(MAKE) $(build)=scripts/kconfig $@ (make -f scripts/Makefile.build obj=scripts/kconfig menuconfig) ，与scripts_basic传的obj路径不一样，这将导致执行Makefile的路径也不一样。

点击(此处)折叠或打开

1. scripts/kconfig/Makefile
2. #没有定义KBUILD_KCONFIG,所以Kconfig=arch/arm/Kconfig    
   
3.      4    ifdef KBUILD_KCONFIG
   
4.      5    Kconfig := $(KBUILD_KCONFIG)
   
5.      6    else
   
6.      7    Kconfig := arch/$(SRCARCH)/Kconfig
   
7.      8    endif        
8.         # 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
   
9.         # 这样就可以看到配置选项
   
10.     16    menuconfig: $(obj)/mconf
    
11.     17        $< $(Kconfig)
    
12.         
    
13.     86    check-lxdialog := $(srctree)/$(src)/lxdialog/check-lxdialog.sh
    
14.     87    
    
15.     88    HOST_EXTRACFLAGS = $(shell $(CONFIG_SHELL) $(check-lxdialog) -ccflags)
    
16.     89    HOST_LOADLIBES = $(shell $(CONFIG_SHELL) $(check-lxdialog) -ldflags $(HOSTCC))
    
17.     90    
    
18.     91    HOST_EXTRACFLAGS += -DLOCALE
    
19.     92    
    
20.     93    
    
21.     94    
    
22.     95    lxdialog := lxdialog/checklist.o lxdialog/util.o lxdialog/inputbox.o
    
23.     96    lxdialog += lxdialog/textbox.o lxdialog/yesno.o lxdialog/menubox.o
    
24.     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
    
25.         #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 
26.     99    mconf-objs    := mconf.o zconf.tab.o $(lxdialog)
    
27.    101    
    
28.    102    hostprogs-y := conf qconf gconf kxgettext
    
29.    103    
    
30.    104    ifeq ($(MAKECMDGOALS),menuconfig)
    
31.    105        hostprogs-y += mconf
    
32.    106    endif
    
33.    130    PHONY += $(obj)/dochecklxdialog
    
34.    131    $(addprefix $(obj)/,$(lxdialog)): $(obj)/dochecklxdialog
    
35.    132    $(obj)/dochecklxdialog:
    
36.    133        $(Q)$(CONFIG_SHELL) $(check-lxdialog) -check $(HOSTCC) $(HOST_EXTRACFLAGS) $(HOST_LOADLIBES)
    
37.    134    
    
38.    135    always := dochecklxdialog

写到快吐了！！！！