https://blog.csdn.net/weixin_55255438/article/details/123562395

下面的源码为4.19内核

Makefile的分类

https://blog.csdn.net/yuhaibin168/article/details/7470301

kernel编译流程

https://blog.csdn.net/jun_8018/article/details/112792967
https://blog.csdn.net/wsyangyue/article/details/82839701
https://www.cnblogs.com/parrynee/archive/2010/05/13/1734689.html
https://blog.csdn.net/yuhaibin168/article/details/7470301
https://zhuanlan.zhihu.com/p/78254770

config目标

%config 目标

https://zhuanlan.zhihu.com/p/362965954
https://blog.csdn.net/weixin_55255438/article/details/123562395

 541 %config: scripts_basic outputmakefile FORCE
 542         $(Q)$(MAKE) $(build)=scripts/kconfig $@

• 依赖目标1：scripts_basic

  470 scripts_basic:
  471         $(Q)$(MAKE) $(build)=scripts/basic
  472         $(Q)rm -f .tmp_quiet_recordmcount

$(Q)$(MAKE) $(build)=scripts/basic即make -f $(srctree)/scripts/Makefile.build obj=scripts/basic，Makefile.build指出默认目标为__build

scripts/Makefile.build的开头会include变量 $(obj)下的Makefile文件，其中就包含 scripts/basic/Makefile：

 6 src := $(obj)

 42 # The filename Kbuild has precedence over Makefile
 43 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
 44 kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
 45 include $(kbuild-file)

scripts/basic/Makefile复写了always变量

 11 hostprogs-y     := fixdep
 12 always          := $(hostprogs-y)
 13 
 14 # fixdep is needed to compile other host programs
 15 $(addprefix $(obj)/,$(filter-out fixdep,$(always))): $(obj)/fixdep

__build目标依赖always变量， $(always) 的值就是 fixdep。

所以，scripts_basic 的目标就干了一件事：生成 fixdep。

• 依赖目标2：outputMakefile

  481 outputmakefile:
  482 ifneq ($(KBUILD_SRC),)
  #在kernel编译输出目录创建一个软链接，指向kernel源码根目录。
  483         $(Q)ln -fsn $(srctree) source
  #将kernel源码根目录的Makefile文件复制到kernel编译输出目录
  484         $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile \
  485             $(srctree) $(objtree) $(VERSION) $(PATCHLEVEL)
  486 endif

• 执行命令生成.config文件：
  https://blog.csdn.net/weixin_39580564/article/details/116820658
  $(Q)$(MAKE) $(build)=scripts/kconfig $@
  假若make的目标为vendor/kona_defconfig，则命令为make -f $(srctree)/scripts/Makefile.build obj=scripts/kconfig vendor/kona_defconfig

则vendor/kona_defconfig目标定义在scripts/kconfig/Makefile中

103 %_defconfig: $(obj)/conf
104         $(Q)$< $(silent) --defconfig=arch/$(SRCARCH)/configs/$@ $(Kconfig)

先忽略$(obj)/conf工具的编译过程
上面完整命令即为：$(Q)scripts/kconfig/conf $(silent) --defconfig=arch/$(SRCARCH)/configs/vendor/kona_defconfig Kconfig，就会读取内核配置文件arch/$(SRCARCH)/configs/vendor/kona_defconfig,然后生成.config文件，注意vendor/kona_defconfig到.config文件并不是简单的拷贝关系。

vmlinux目标（缺省目标，生成最原始的未压缩的内核镜像vmlinux）

https://blog.csdn.net/weixin_36098975/article/details/135140530 （***）
https://zhuanlan.zhihu.com/p/571078063
https://www.cnblogs.com/jianhua1992/p/16852799.html

vmlinux目标依赖图

https://zhuanlan.zhihu.com/p/646773422

内核镜像组成

https://blog.csdn.net/ldl617/article/details/126932099
https://blog.csdn.net/Lsq111112/article/details/129410284
vmlinx--->objcopy--->Image--->gzip--->arch/arm/boot/compressed/vmlinx--->objcopy--->zImage--->mkimage--->uImage