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分析过程＿/span>
查看arch\arm\Makefile下的第一个目标为all: zImage
找到仿/span>zImage作为目标的规则：
zImage Image xipImage bootpImage uImage: vmlinux
$(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@
这个规则中命令执行的目录丿/span>$(boot)= arch/arm/boot,那么读取arch/arm/boot下的Makefile找到了这丿/span>Makefile中的第一条规刿/span>targets := Image zImage xipImage bootpImage uImage
＿）查眿/span>arch/arm/boot下的Makefile中的规则＿/span>
$(obj)/Image: vmlinux FORCE
$(call if_changed,objcopy)
@echo ' Kernel: $@ is ready'
要生成非压缩的内栿/span>Image，依赖的文件昿/span>vmlinux, 根据顶层Makefile中的规则＿/span>vmlinux的生成需要文仿/span>$(head-y)，在arch\arm\Makefile下定义了
$(head-y) := arch/arm/kernel/head$(MMUEXT).o arch/arm/kernel/init_task.o
由此可以看出皿/span>Image 的入口程序为 Kernel皿/span>head.S
＿）查眿/span>arch/arm/boot下的Makefile中的规则＿/span>
$(obj)/zImage: $(obj)/compressed/vmlinux FORCE
$(call if_changed, objcopy)
@echo ' Kernel: $@ is ready'
可知压缩的内栿/span>zImage的依赖体昿/span>$(obj)/compressed/vmlinux
查看arch\arm\boot\compressed\Makefile中两条规则：
targets := vmlinux vmlinux.lds piggy.gz piggy.o $(FONT) head.o misc.o head.o misc.o $(OBJS)
$(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.o \
$(addprefix $(obj)/, $(OBJS)) FORCE
$(call if_changed,ld)
@:
其中$(HEAD):=head.o
有上述两条规则可知：zImage 的入口程序即arch/arm/boot/compressed/head.S
＿）查眿/span>arch/arm/boot下的Makefile中的另外两条规则＿/span>
$(obj)/bootp/bootp: $(obj)/zImage initrd FORCE
$(Q)$(MAKE) $(build)=$(obj)/bootp $@
@:
$(obj)/bootpImage: $(obj)/bootp/bootp FORCE
$(call if_changed,objcopy)
@echo ' Kernel: $@ is ready'
bootpImage的组成部分为bootp, bootp的组成部分为zImage咿/span>initrd
查看arch/arm/boot/bootp/下的Makefile的规刿/span>
$(obj)/bootp: $(src)/bootp.lds $(addprefix $(obj)/, init.o kernel.o initrd.o) FORCE
$(call if_changed,ld)
@:
$(obj)/kernel.o: arch/arm/boot/zImage FORCE
$(obj)/initrd.o: $(INITRD) FORCE
从上面的规则可知＿/span>bootpImage 的入口程序即arch/arm/boot/bootp/init.S
发表亿@ 2009广3朿9旿18:31:00|评论(loading...)|编辑|举报|
(转自:http://blog.csdn.net/liucong2004/archive/2009/03/19/4005409.aspx)
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