make syncconfig V=1分析

make syncconfig

# 顶层 Makefile
94 	ifeq ("$(origin V)", "command line")
95 	  KBUILD_VERBOSE = $(V)
96 	endif
97 	ifndef KBUILD_VERBOSE
98 	  KBUILD_VERBOSE = 0
99 	endif
100
101	ifeq ($(KBUILD_VERBOSE),1)
102	  quiet =
103	  Q =
104	else
105	  quiet=quiet_
106	  Q = @
107	endif
......	
563	%config: scripts_basic outputmakefile FORCE
564		$(Q)$(MAKE) $(build)=scripts/kconfig $@
......
2318 FORCE:

执行命令 make syncconfig V=1 时，94行条件成立，KBUILD_VERBOSE = 1，则101行条件成立，quiet 和 Q 为空，则输出整个命令。
在顶层Makefile的 <386行> 引用scripts/Kbuild.include，其中有如下定义：

# scripts/Kbuild.include 
184	build := -f $(srctree)/scripts/Makefile.build obj

最终展开为：

# make syncconfig V=1
# 顶层 Makefile
563	syncconfig: scripts_basic outputmakefile FORCE
564		make -f ./scripts/Makefile.build obj=scripts/kconfig syncconfig

由上可知，依赖关系如下图所示：

1. 创建目标syncconfig，见《4. make -f ./scripts/Makefile.build obj=scripts/kconfig syncconfig》， 回显 4-10
   1.1 创建 scripts_basic ，见《1. 创建 scripts_basic》， 回显 1-3
   1.2 创建 outputmakefile，见《2. 创建 outputmakefile》，什么都不做
   1.3 创建 FORCE，什么都不做

 
最终：《2. conf 工具》

 
回显 1-10

1 make -f ./scripts/Makefile.build obj=scripts/basic
2   cc -Wp,-MD,scripts/basic/.fixdep.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -std=gnu11     -o scripts/basic/fixdep scripts/basic/fixdep.c   
3 rm -f .tmp_quiet_recordmcount
4 make -f ./scripts/Makefile.build obj=scripts/kconfig syncconfig
5   cc -Wp,-MD,scripts/kconfig/.conf.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -std=gnu11     -c -o scripts/kconfig/conf.o scripts/kconfig/conf.c
6   bison -oscripts/kconfig/zconf.tab.c -t -l scripts/kconfig/zconf.y
7   flex -oscripts/kconfig/zconf.lex.c -L scripts/kconfig/zconf.l
8   cc -Wp,-MD,scripts/kconfig/.zconf.tab.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -std=gnu11    -Iscripts/kconfig -c -o scripts/kconfig/zconf.tab.o scripts/kconfig/zconf.tab.c
9   cc   -o scripts/kconfig/conf scripts/kconfig/conf.o scripts/kconfig/zconf.tab.o   
10 scripts/kconfig/conf --syncconfig Kconfig