zImage的生成过程

[Author: Bo Shen <voice.shen@gmail.com>]

前面讲了uImage的生成过程(http://blog.youkuaiyun.com/voice_shen/article/details/6559752)。uImage会依赖zImage。那么下面就具体分析zImage生成过程。

其实zImage的生成过程更简单，源代码 <arm/arm/boot/Makefile>,如下：

$(obj)/zImage:  $(obj)/compressed/vmlinux FORCE
        $(call if_changed,objcopy)
        @$(kecho) '  Kernel: $@ is ready'

从源码可知，zImage是由<arm/arm/boot/compressed/vmlinux>通过objcopy生成。

if_changed命令从那里来呢？查看源码，发现其在<scripts/Kbuild.include>里面定义。

--->8---

# if_changed  - execute command if any prerequisite is newer than target, or command line has changed.

---8<---

当执行$(call if_changed, objcopy)命