2.整理内核编译流程：uImage/zImage/Image/vmlinx之间关系

uImage镜像文件的分析

1.在内核源码顶层目录下打开Makefile文件，搜索uImage,发现没有目标，猜测在Makefile中包含其他路径的Makefile文件
596 include arch/$(SRCARCH)/Makefile = arch/arm/Makefile2.进入arch/arm目录下，打开Makefile文件，搜索uImage，打印每个变量信息
323 $(BOOT_TARGETS): vmlinux
324 $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@打印信息内容：
@ -f ./scripts/Makefile.build obj arch/arm/boot uImage make -f ./scripts/Makefile.build obj=arch/arm/boot MACHINE=arch/arm/boot/uImage
3.进入内核源码/scripts/Makefile.build文件，搜索uImage
6 src := $(obj)=arch/arm/boot
42 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src)) kbuild-dir :=$(src)
43 kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile) kbuild-file := $(kbuild-dir)/Kbuild和$(kbuild-dir)/Makefile
44 include $(kbuild-file) ：将 arch/arm/boot/Makefile和当前的Makfile.build文件合并
4.进入内核源码arch/arm/boot/,打开Makefile文件，搜索uImage
89 $(obj)/uImage: $(obj)/zImage FORCE
90 @$(check_for_multiple_loadaddr) ------->检测uImage镜像文件的入口地址
91 $(call if_changed,uimage)------->call:调用if_changed命令,makefile中固定的用法
5. 入内核源码arch/arm/boot/,打开Makefile文件，
指定LOADADDR这个变量的信息，将加载的地址赋值
70 LOADADDR = 0xc2000000 -------> 需要添加内容 71 ifneq ($(LOADADDR),)
72 UIMAGE_LOADADDR=$(LOADADDR)
6.进入内核源码
scripts/Kbuild.include目录下，搜索:if_changed
218 if_changed = $(if $(newer-prereqs)$(cmd-check),
219 $(cmd);
183 cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(cmd_$(1)) @set -e:在执行的时候有错误就直接退出 $(cmd_$(1)) = cmd_uimage
7. 进入内核源码scripts/Makefile.lib目录下,搜索cmd_uimage
398 cmd_uimage = $(BASH) $(MKIMAGE) -A $(UIMAGE_ARCH) -O linux \
399 -C $(UIMAGE_COMPRESSION) $(UIMAGE_OPTS-y) \
400 -T $(UIMAGE_TYPE) \
401 -a $(UIMAGE_LOADADDR) -e $(UIMAGE_ENTRYADDR) \
402 -n $(UIMAGE_NAME) -d $< $@
解析： 385 MKIMAGE := ./scripts/mkuboot.sh cmd_uimage = /usr/bin/mkimage -A arm -O linux -C gzip -T kernel -n uImage -d zImage
8.uImage和zImage之间关系？
1）uImage使用在zImage使用mkimage工具得到的，uImage在zImage前添加64字节头部信息
2）每次编译打印信息的内容就是编译到uImage中内容
Image Name: Linux-5.10.61 Created: Wed Mar 8 16:15:39
2023 Image Type: ARM Linux Kernel Image (uncompressed) Data Size: 717
2080 Bytes = 7003.98 KiB = 6.84 MiB Load Address: c2000000 Entry Point: c2000000

2..zImage镜像文件的分析

1.进入内核源码arch/arm/boot/,打开Makefile文件，搜索zImage
66 $(obj)/zImage: $(obj)/compressed/vmlinux FORCE 67 $(call if_changed,objcopy) ---->cmd_objcopy
267 cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
arm-linux-gnueabihf-objcopy $(obj)/compressed/vmlinux zImage
2.zImage和arch/arm/boot/compressed/vmlinux关系？
zImage是通过vmlinux格式化转换为的文件

3.compressed/vmlinux文件

1.进入内核源码arch/arm/boot/,打开Makefile文件，搜索vmlinux
63 $(obj)/compressed/vmlinux: $(obj)/Image FORCE 64 $(Q) $(MAKE) $(build)=$(obj)/compressed $@
执行命令：make -f ./scripts/Makefile.build obj=arch/arm/boot/compressed arch/arm/boot/compressed/vmlinux
2.进入内核源码arch/arm/boot/compressed,打开Makefile文件，搜索vmlinux
178 $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.o \
179 $(addprefix $(obj)/, $(OBJS)) $(lib1funcs) $(ashldi3) \
180 $(bswapsdi2) $(efi-obj-y) FORCE
182 $(call if_changed,ld) ---->cmd_ld
arch/arm/boot/vmlinux.lds head.o piggy.o debug.o lib1funcs.o lib1funcs.S ashldi3.S bswapsdi2.S hyp-stub.S bswapsdi2.o lib.a
arm-linux-gnueabihf-ld vmlinux.lds head.o piggy.o debug.o lib1funcs.o lib1funcs.S ashldi3.S bswapsdi2.S hyp-stub.S bswapsdi2.o lib.a -o vmlinux
185 $(obj)/piggy_data: $(obj)/../Image FORCE
186 $(call if_changed,$(gzip)) ----->调用cmd_gzip
188 $(obj)/piggy.o: $(obj)/piggy_data
3.进入内核源码scripts/Makefile.lib目录下,搜索cmd_gzip
cmd_gzip = $(KGZIP) -n -f -9 > $@ = gzip Image > vmlinx4.rch/arm/boot/compressedvmlinux文件和Image之间关系
将Image镜像文件经过gzip压缩生成rch/arm/boot/compressed/vmlinx镜像文件

4.Image镜像文件

.进入内核源码arch/arm/boot/compressed,打开Makefile文件，搜索Image
60 $(obj)/Image: vmlinux FORCE
61 $(call if_changed,objcopy) ----->调用cmd_objcopy
2.Image和内核顶层目录下vmlinx关系
vmlinux通过objcopy格式化转换为Image

5.总结