uImage生成过程

 

当编译linux的时候，运行make uImage，如果一切正常，最后会生成uImage。

如下具体讲解uImage生成过程：

1. 生成uImag的工具mkimage由arch/arm/boot/Makefile中的MKIMAGE定义

MKIMAGE         := $(srctree)/scripts/mkuboot.sh

MKIMAGE := $(srctree)/scripts/mkuboot.sh

mkuboot.sh的作用是去找到是否存在"mkimage"，此工具是用来生成最后的uImage。

  mkuboot.sh 首先检查toolchain是否拥有mkimage (使用-z来判空)，如果没有，再检查系统中是否拥有mkimage；如果没有则报错。

注：其中使用type命令来查找。

        type: Display information about command type  (type [-afptP] name [name ...])

       ==> # type mkimage

      ==> mkimage is /usr/bin/mkimage

2. 从makefile.boot中传入生成uImage的相关参数（e.g: arm/arm/mach-at91/Makefile.boot）

ifneq ($(MACHINE),)
include $(srctree)/$(MACHINE)/Makefile.boot
endif

ifneq ($(MACHINE),) include $(srctree)/$(MACHINE)/Makefile.boot endif

3.  通过mkimage来生成uImage，其过程是加上0x40 bytes 的kernel头

quiet_cmd_uimage = UIMAGE  $@
      cmd_uimage = $(CONFIG_SHELL) $(MKIMAGE) -A arm -O linux -T kernel /
           -C none -a $(LOADADDR) -e $(STARTADDR) /
           -n 'Linux-$(KERNELRELEASE)' -d $< $@

quiet_cmd_uimage = UIMAGE $@ cmd_uimage = $(CONFIG_SHELL) $(MKIMAGE) -A arm -O linux -T kernel / -C none -a $(LOADADDR) -e $(STARTADDR) / -n 'Linux-$(KERNELRELEASE)' -d $< $@

mkimage的参数如下：

Usage: mkimage -l image
          -l ==> list image header information
       mkimage [-x] -A arch -O os -T type -C comp -a addr -e ep -n name -d data_file[:data_file...] image
          -A ==> set architecture to 'arch'
          -O ==> set operating system to 'os'
          -T ==> set image type to  'type'
          -C ==> set compression type 'comp'
          -a ==> set load address to 'addr' (hex)
          -e ==> set entry point to 'ep' (hex)
          -n ==> set image name to  'name'
          -d ==> use image data from 'datafile'
          -x ==> set XIP (execute  in place)

Usage: mkimage -l image -l ==> list image header information mkimage [-x] -A arch -O os -T type -C comp -a addr -e ep -n name -d data_file[:data_file...] image -A ==> set architecture to 'arch' -O ==> set operating system to 'os' -T ==> set image type to 'type' -C ==> set compression type 'comp' -a ==> set load address to 'addr' (hex) -e ==> set entry point to 'ep' (hex) -n ==> set image name to 'name' -d ==> use image data from 'datafile' -x ==> set XIP (execute in place)

Load address 由下面代码获得

ifeq ($(CONFIG_ZBOOT_ROM),y)
$(obj)/uImage: LOADADDR=$(CONFIG_ZBOOT_ROM_TEXT)
else
$(obj)/uImage: LOADADDR=$(ZRELADDR)
endif

ifeq ($(CONFIG_ZBOOT_ROM),y) $(obj)/uImage: LOADADDR=$(CONFIG_ZBOOT_ROM_TEXT) else $(obj)/uImage: LOADADDR=$(ZRELADDR) endif

start address 由下面代码获得

$(obj)/uImage: STARTADDR=$(LOADADDR)

$(obj)/uImage: STARTADDR=$(LOADADDR)

由zImage生成uImage:

$(obj)/uImage:  $(obj)/zImage FORCE
    $(call if_changed,uimage)
    @echo '  Image $@ is ready'

$(obj)/uImage: $(obj)/zImage FORCE $(call if_changed,uimage) @echo ' Image $@ is ready'

也可以自行用mkimage来生成uImage，

  mkimage -A arm -O linux -T kernel -C none -a -e -n -d zImage uImage

e.g : mkimage -A arm -O linux -T kernel -C none -a 0x70008000 -e 0x70008000 -n linux-2.6.30 -d zImage uImage

其中：0x8000这32K 空间是：Note that the kernel uses 16K of RAM below the image to store page tables.  The recommended placement is 32KiB into RAM. （来自Documentation/arm/booting文件）

 

文章转自：http://blog.csdn.net/voice_shen/article/details/6559752