linux_2.6.30.4_Makefile_4--make zImage流程

为解惑生成zImage的过程，查到此文，地址：http://blog.chinaunix.net/uid-26009923-id-3194580.html

    分析一下make zImage的流程，具体的操作是：首先将linux-2.6.30.4/config_EmbedSky_W35_256MB改名为.config，然后make zImage.看一下make zImage之后发生了什么事情。

点击(此处)折叠或打开

 linux-2.6.30.4/Makefile
 284 #config-targets=0, mixed-targets=0, dot-config=1,不会进入L285
 285 ifeq ($(mixed-targets),1) #不成立跳过
 ...
 291 ifeq ($(config-targets),1) #不成立跳过
 304 else
 305
 306 ifeq ($(KBUILD_EXTMOD),)
 ......
 354 include $(srctree)/arch/$(SRCARCH)/Makefile

在 arch/arm/Makefile中包含了zImage

点击(此处)折叠或打开

   linux-2.6.30.4/arch/arm/Makefile
    174    ifeq ($(CONFIG_XIP_KERNEL),y)
    175    KBUILD_IMAGE := xipImage
    176    else
    177    KBUILD_IMAGE := zImage
    178    endif
    179
    180    all:    $(KBUILD_IMAGE)
    181
    182    boot := arch/arm/boot
    183
    193    zImage Image xipImage bootpImage uImage: vmlinux
    194        $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@
 #zImage依赖于vmliux, vmliux在linux-2.6.30.4/Makefile中

1. linux-2.6.30.4/Makefile 中包含了arch/arm/Makefile

2. 在 arch/arm/Makefile中找到目标zImage

3. zImage依赖linux-2.6.30.4中的Makefile中vmlinux

4. 分析 linux-2.6.30.4/Makefile中vmlinux的依赖

5.

就第4步进行具体分析

点击(此处)折叠或打开

    306    ifeq ($(KBUILD_EXTMOD),)
    307    PHONY += scripts
    308    scripts: scripts_basic include/config/auto.conf
    309        $(Q)$(MAKE) $(build)=$(@)
    310
    311    init-y        := init/
    312    drivers-y    := drivers/ sound/ firmware/
    313    net-y        := net/
    314    libs-y        := lib/
    315    core-y        := usr/
    316    endif # KBUILD_EXTMOD
    317
    318    ifeq ($(dot-config),1)
    319    -include include/config/auto.conf
    320
    321    ifeq ($(KBUILD_EXTMOD),)
    322    -include include/config/auto.conf.cmd
    323
    324    $(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;
    325
    326    include/config/auto.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
    327        $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
    328    else
    329    PHONY += include/config/auto.conf
    330
    331    include/config/auto.conf:
    332        $(Q)test -e include/linux/autoconf.h -a -e $@ || (        \
    333        echo;                                \
    334        echo " ERROR: Kernel configuration is invalid.";        \
    335        echo " include/linux/autoconf.h or $@ are missing.";    \
    336        echo " Run 'make oldconfig && make prepare' on kernel src to fix it.";    \
    337        echo;                                \
    338        /bin/false)
    339
    340    endif # KBUILD_EXTMOD

 #vmliux的依赖vmlinux-lds=arch/arm/kernel/vmlinux.lds vmlinux-init=arch/arm/kernel/head-nommu.o arch/arm/      kernel/init_task.o  init/built-in.o vmlinux-main= usr/built-in.o  arch/arm/kernel/built-in.o  arch/arm/mm/built-in.o  arch/arm/common/built-in.o  kernel/built-in.o  mm/built-in.o  fs/built-in.o  ipc/built-in.o  security/    built-in.o  crypto/built-in.o  block/built-in.o  arch/arm/lib/lib.a  lib/lib.a  arch/arm/lib/built-in.o  lib/   built-in.o  drivers/built-in.o  sound/built-in.o  firmware/built-in.o  net/built-in.o kallsyms=
    576    vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o $(kallsyms.o) FORCE
 #vmlinux-lds等 依赖于vmlinux-dirs
    598    $(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;

    601    PHONY += $(vmlinux-dirs)
    602    $(vmlinux-dirs): prepare scripts
    603        $(Q)$(MAKE) $(build)=$@

    636    prepare3: include/config/kernel.release
    649
    650    prepare2: prepare3 outputmakefile
    651
    652    prepare1: prepare2 include/linux/version.h include/linux/utsrelease.h \
    653     include/asm include/config/auto.conf
    654        $(cmd_crmodverdir)
    655
    656    archprepare: prepare1 scripts_basic
    657
    658    prepare0: archprepare FORCE
    659        $(Q)$(MAKE) $(build)=.
    660        $(Q)$(MAKE) $(build)=. missing-syscalls
    661
    662    prepare: prepare0

 整理一下上述的各个依赖关系，如下图所示

 下面按照执行的顺序详细分析一下，各个步骤：
 4.1 首先执行的是scripts的过程：
     这个过程类似于make menuconfig的过程，只不过最后调用的是:conf -s ,不产生图形界面。  
     
      
       点击(此处)折叠或打开 
      
      
       scrpts的过程:
  326    include/config/auto.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
  327        $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
  即: make -f /root/kernel/linux-2.6.30.4/Makefile silentoldconfig
      make -f scripts/Makefile.build obj=scripts/basic
      mkdir -p include/linux include/config
      make -f scripts/Makefile.build obj=scripts/kconfig silentoldconfig
      scripts/kconfig/conf -s arch/arm/Kconfig
 4.2 其次执行的是prepare的过程：

 
     
      
       点击(此处)折叠或打开 
      
      
       linux-2.6.30.4/Makefile 中archprepare: prepare1 scripts_basic
 而在
 arch/arm/Makefile中archprepare: maketools
 这地方有点没有看明白，在Makefile和arch/arm/Makefile中都有archprepare的规则，
 什么这两个都执行了，而不是一个覆盖另一个？

    linux-2.6.30.4/Makefile
    714    include/linux/version.h: $(srctree)/Makefile FORCE
    715        $(call filechk,version.h)
    这将会调用linux-2.6.30.4/scripts/Kbuild.include中的filechk函数,主要作用是：用Makefile中的版本信息更新include/linux/version.h中的版本信息。

   arch/arm/Makefile
   $(Q)$(MAKE) $(build)=arch/arm/tools include/asm-arm/mach-types.h
  即: make -f scripts/Makefile.build obj=arch/arm/tools include/asm-arm/mach-types.h
  这会调用arch/arm/tools/Makefile中的规则产生include/asm-arm/mach-types.h 文件

    linux-2.6.30.4/Makefile
    628    include/config/kernel.release: include/config/auto.conf FORCE
    629        $(Q)rm -f $@
    630        $(Q)echo $(kernelrelease) > $@
    这会产生kernel.release文件: echo 2.6.30.4-EmbedSky > include/config/kernel.release

    linux-2.6.30.4/Makefile
    717    include/linux/utsrelease.h: include/config/kernel.release FORCE
    718        $(call filechk,utsrelease.h)
 这将会调用linux-2.6.30.4/scripts/Kbuild.include中的filechk函数，主要是检查include/config/kernel.release中的kernel版本信息是否超过64字节，超过则报错。

    linux-2.6.30.4/Makefile
    693    include/asm: FORCE
    694        $(Q)$(check-symlink)
    695        $(Q)$(create-symlink)
   #刚生出来(下载)的内核代码是不存在include/asm目录的，check-symlink是检查include/asm是存在并指向asm-arm,如果不存在asm-arm的符号连接则创建，存在但不正确就打印出错信息。

    linux-2.6.30.4/Makefile
    prepare1的最后执行 $(cmd_crmodverdir)
    1146    cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \
    1147     $(if $(KBUILD_MODULES),; rm -f $(MODVERDIR)/*)
    即:mkdir -p .tmp_versions

    linux-2.6.30.4/Makefile
    archprepare的第二个依赖 scripts_basic
    即:make -f scripts/Makefile.build obj=scripts/basic

    linux-2.6.30.4/Makefile
    prepare0的依赖执行完之后，执行：
    make -f scripts/Makefile.build obj=.
 #执行scripts/Makefile的__build目标，此处只执行always依赖，(KBUILD_BUILTIN=1，但是$(builtin-target) $(lib-target) $(extra-y)都为空，KBUILD_MODULES=0)
 always=./include/linux/bounds.h ./include/asm/asm-offsets.h
 __build: ./include/linux/bounds.h ./include/asm/asm-offsets.h
 :
 这将会编译kernel/bounds.c 和 arch/arm/kernel/asm-offsets.c两个文件 
      
     4.3 vmlinux-dirs的依赖执行完了之后，再去执行vmlinux-dirs的命令了 
     
      
       点击(此处)折叠或打开 
      
      
       linux-2.6.30.4/Makefile
  880 PHONY += $(vmlinux-dirs)
  881 $(vmlinux-dirs): prepare scripts
  882 $(Q)$(MAKE) $(build)=$@
 由于命令中用到$@即vmlinux-dirs先转到vmlinux-dirs的定义处:

 linux-2.6.30.4/Makefile
  653 vmlinux-dirs := $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
  654 $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
  655 $(net-y) $(net-m) $(libs-y) $(libs-m)))
 可以看到vmlinux-dirs是:
 vmlinux-dirs=init usr arch/arm/kernel arch/arm/mm arch/arm/common arch/arm/mach-s3c2410 arch/arm/mach-s3c2400 arch/arm/mach-s3c2412 arch/arm/mach-s3c2440 arch/arm/mach-s3c2442 arch/arm/mach-s3c2443 arch/arm/plat-s3c24xx arch/arm/plat-s3c kernel mm fs ipc security crypto block drivers sound firmware net arch/arm/lib lib
 这就是要去内核的每一个目录下面去编译需要的每一个源文件了

 make -f scripts/Makefile.build obj=init
 #builtin-target=init/built-in.o lib-target= extra-y= subdir-ym= always=

 linux-2.6.30.4/scripts/Makefile.build
  93 __build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
  94 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
  95 $(subdir-ym) $(always)
  96 @:
 #此时只有builtin-target=init/built-in.o有定义，下一步生成目标builtin-target

 linux-2.6.30.4/scripts/Makefile.build
 286 ifdef builtin-target
 287 quiet_cmd_link_o_target = LD $@
 288 # If the list of objects to link is empty, just create an empty built-in.o
 289 cmd_link_o_target = $(if $(strip $(obj-y)),\
 290 $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \
 291 $(cmd_secanalysis),\
 292 rm -f $@; $(AR) rcs $@)
 293
 294 $(builtin-target): $(obj-y) FORCE
 295 $(call if_changed,link_o_target)

 #先去执行builtin-target的依赖obj-y，将所以.c编译为.o, .s编译为.o
 obj-y=init/main.o init/version.o init/mounts.o init/noinitramfs.o init/calibrate.o
 ld
 把obj-y链接成init/built-in.o
 目标vmlinux-dirs执行完成后，built-in.o

  $(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;
 因为这个指令是一个空指令，所以当vmlinux-dirs执行完成之后,vmlinux的依赖$(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds)都准备好了。 
      
     4.4 vmlinux的两个依赖: vmlinux.o与$(kallsyms.o) 
     
      
       点击(此处)折叠或打开 
      
      
       4.4.1 vmlinux的一个依赖是:vmlinux.o
 linux-2.6.30.4/Makefile
  866 vmlinux.o: $(modpost-init) $(vmlinux-main) FORCE
  867 $(call if_changed_rule,vmlinux-modpost)

 linux-2.6.30.4/scripts/Kbuild.include
 208 if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \
 209 @set -e; \
 210 $(rule_$(1)))
 #如果目标有更新则执行rule_vmlinux-modpost
 linux-2.6.30.4/Makefile
  838 define rule_vmlinux-modpost
  839 :
  840 +$(call cmd,vmlinux-modpost)
  841 $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $@
  842 $(Q)echo 'cmd_$@ := $(cmd_vmlinux-modpost)' > $(dot-target).cmd
  843 endef

 linux-2.6.30.4/Makefile
  834 quiet_cmd_vmlinux-modpost = LD $@
  835 cmd_vmlinux-modpost = $(LD) $(LDFLAGS) -r -o $@ \
  836 $(vmlinux-init) --start-group $(vmlinux-main) --end-group \
  837 $(filter-out $(vmlinux-init) $(vmlinux-main) FORCE ,$^)
 #首先链接生成vmlinux.o: L834 arm-linux-ld -EL -r -o vmlinux.o
 然后执行:make -f /root/kernel/linux-2.6.30.4/scripts/Makefile.modpost vmlinux.o，
 最后把链接生成vmlinux.o的过程打印到.cmd文件中

 linux-2.6.30.4/scripts/Makefile.modpost
 103 vmlinux.o: FORCE
 104 @rm -fr $(kernelmarkersfile)
 105 $(call cmd,kernel-mod)
 然后执行:
 101 cmd_kernel-mod = $(modpost) $@
 即:scripts/mod/modpost -o /root/kernel/linux-2.6.30.4/Module.symvers -S -c vmlinux.o
 用scripts/mod/modpost处理vmlinux.o，得到Module.symvers,这个具体有什么作用现在还没有搞清楚。


 4.4.2 vmlinux的一个依赖是:$(kallsyms.o)=.tmp_kallsyms2.o
  801 .tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms3.o: %.o: %.S scripts FORCE
  802 $(call if_changed_dep,as_o_S)

 .tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms3.o: %.o: %.S scripts FORCE
 依赖中又含有%.o: %.S ? 没看明白
 看到打印中: /opt/EmbedSky/4.3.3/bin/arm-none-linux-gnueabi-nm -n .tmp_vmlinux2 | scripts/kallsyms > .tmp_kallsyms2.S
 然后通过: arm-linux-gcc $(a_flags) -c -o .tmp_kallsyms2.o .tmp_kallsyms2.S

 linux-2.6.30.4/scripts/Kbuild.include
 198 if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \
 199 @set -e; \
 200 $(echo-cmd) $(cmd_$(1)); \
 201 scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
 202 rm -f $(depfile); \
 203 mv -f $(dot-target).tmp $(dot-target).cmd)

 #执行cmd_as_o_S
 linux-2.6.30.4/scripts/Makefile
 1580 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
 4.5 当vmlinux的所有依赖都ok之后，执行vmlinux的命令 
     
      
       点击(此处)折叠或打开 
      
      
       845 # vmlinux image - including updated kernel symbols
  846 vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o $(kallsyms.o) FORCE
  847 ifdef CONFIG_HEADERS_CHECK
  848 $(Q)$(MAKE) -f $(srctree)/Makefile headers_check
  849 endif
  850 ifdef CONFIG_SAMPLES
  851 $(Q)$(MAKE) $(build)=samples
  852 endif
  853 ifdef CONFIG_BUILD_DOCSRC
  854 $(Q)$(MAKE) $(build)=Documentation
  855 endif
  856 $(call vmlinux-modpost)
  857 $(call if_changed_rule,vmlinux__)
  858 $(Q)rm -f .old_version

 #CONFIG_HEADERS_CHECK CONFIG_SAMPLES CONFIG_BUILD_DOCSRC都为空，所以
 4.5.1 $(call vmlinux-modpost) ;没找到定义
 4.5.2 $(call if_changed_rule,vmlinux__) ;具体分析
 4.5.3 $(Q)rm -f .old_version


 linux-2.6.30.4/scripts/Kbuild.include
 208 if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ),                 \
 209     @set -e;                                                             \
 210     $(rule_$(1)))
 #如果目标有更新则执行rule_vmlinux__

 linux-2.6.30.4/Makefile
  731 define rule_vmlinux__
  732     :
  733     $(if $(CONFIG_KALLSYMS),,+$(call cmd,vmlinux_version))
  734
  735     $(call cmd,vmlinux__)
  736     $(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
  737
  738     $(Q)$(if $($(quiet)cmd_sysmap),                                      \
  739       echo '  $($(quiet)cmd_sysmap)  System.map' &&)                     \
  740     $(cmd_sysmap) $@ System.map;                                         \
  741     if [ $$? -ne 0 ]; then                                               \
  742         rm -f $@;                                                    \
  743         /bin/false;                                                  \
  744     fi;
  745     $(verify_kallsyms)
  746 endef
 L733行 CONFIG_KALLSYMS=y，所以不做任何操作
 L735行 在linux-2.6.30.4/scripts/Kbuild.include L160 cmd = @$(echo-cmd) $(cmd_$(1)),打印并执行cmd_vmlinux__

 linux-2.6.30.4/Makefile
  704 quiet_cmd_vmlinux__ ?= LD      $@
  705       cmd_vmlinux__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \
  706       -T $(vmlinux-lds) $(vmlinux-init)                          \
  707       --start-group $(vmlinux-main) --end-group                  \
  708       $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o FORCE ,$^)
 #链接生成vmlinux的过程:
 L735 arm-linux-ld  -o vmlinux -Tarch/arm/kernel/vmlinux.lds
 L736 将链接生成vmlinux的过程写入到.cmd中
 L738   在linux-2.6.30.4/Makefile中 L724 cmd_sysmap = $(CONFIG_SHELL) $(srctree)/scripts/mksysmap

 .scripts/mksysmap  System.map
 ./scripts/mksysmap vmlinux System.map
 if [ $? -ne 0 ];
     then rm -f vmlinux;
 /bin/false;
 fi

 L858 rm -f .old_version 
      
     5. 生成最终的zImage 
     
      
       点击(此处)折叠或打开 
      
      
       终于zImage的依赖vmlinux执行完了,下面回到arch/arm/Makefile中执行zImge的命令过程：
 linux-2.6.30.4/arch/am/Makefile
 230 zImage Image xipImage bootpImage uImage: vmlinux
 231   $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@
  #make -f scripts/Makefile.build obj=arch/arm/boot MACHINE=arch/arm/mach-s3c2410/ arch/arm/boot/zImage

 #执行arch/arm/boot/Makefile中的zImage
 linux-2.6.30.4/arch/arm/boot/Makefile
  56 $(obj)/zImage: $(obj)/compressed/vmlinux FORCE
  57 $(call if_changed,objcopy)
  58 @cp -f arch/arm/boot/zImage zImage.bin
  59 @echo ' Kernel: $@ is ready'
 首先生成arch/arm/boot/compress/vmlinux

 linux-2.6.30.4/arch/arm/boot/Makefile中
  53 $(obj)/compressed/vmlinux: $(obj)/Image FORCE
  54 $(Q)$(MAKE) $(build)=$(obj)/compressed $@
   make -f scripts/Makefile.build obj=arch/arm/boot/compressed arch/arm/boot/compressed/vmlinux

 执行arch/arm/boot/compress/Makefile
 linux-2.6.30.4/arch/arm/boot/compressed/Makefile
  94 $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.o \
  95 $(addprefix $(obj)/, $(OBJS)) FORCE
  96 $(call if_changed,ld)
  97 @:

 #arm-linux-gcc  -c -o arch/arm/boot/compressed/head.o arch/arm/boot/compressed/head.S
 linux-2.6.30.4/arch/arm/boot/compressed/Makefile
 102 $(obj)/piggy.o: $(obj)/piggy.gz FORCE
 gzip -f -9 < arch/arm/boot/compressed/../Image > arch/arm/boot/compressed/piggy.gz
 piggy.o
 #arm-linux-gcc  -c -o arch/arm/boot/compressed/piggy.o arch/arm/boot/compressed/piggy.S

 #arm-linux-gcc  -c -o arch/arm/boot/compressed/misc.o arch/arm/boot/compressed/misc.c

 #arm-linux-ld  -T arch/arm/boot/compressed/vmlinux.lds compressed/head.o piggy.o misc.o -o arch/arm/boot/compressed/vmlinux

 linux-2.6.30.4/arch/arm/boot/Makefile
  56 $(obj)/zImage: $(obj)/compressed/vmlinux FORCE
  57 $(call if_changed,objcopy)
  58 @cp -f arch/arm/boot/zImage zImage.bin
  59 @echo ' Kernel: $@ is ready'
 #好了compressed/vmlinux也生成了，最后一步$(call if_changed, objcopy)

 linux-2.6.30.4/scripts/Kbuild.include
 192 if_changed = $(if $(strip $(any-prereq) $(arg-check)), \
 193 @set -e; \
 194 $(echo-cmd) $(cmd_$(1)); \
 195 echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
 #打印并执行$(cmd_objcopy)，最后把$(cmd_objcopy)写到.cmd文件中

 linux-2.6.30.4/scripts/Makefile.lib
 184 quiet_cmd_objcopy = OBJCOPY $@
 185 cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
 即:arm-linux-objcopy -O binary -R .note -R .note.gnu.build-id -R .comment -S arch/arm/boot/compressed/vmlinux arch/arm/boot/zImage
 将vmlinux这个elf的二进制文件，转换为raw二进制文件。 
      
     终于完成了，zImage的过程，不容易啊！