基于Linux2.6.38.8内核zImage文件的自解压详解
基于Linux2.6.38.8内核zImage文件的自解压详解
Linux内核编译完成后会生成zImage内核镜像文件。zImage是如何解压的呢?本文将结合关键代码,讲解zImage的解压过程。还是先来看看zImage的组成吧。在内核编译完成后会在arch/arm/boot/下生成zImage。在arch/arm/boot/Makefile中,如下代码:
[plain]- #
- # arch/arm/boot/Makefile
- #
- # This file is included by the global makefile so that you can add your own
- # architecture-specific flags and dependencies.
- #
- # This file is subject to the terms and conditions of the GNU General Public
- # License. See the file "COPYING" in the main directory of this archive
- # for more details.
- #
- # Copyright (C) 1995-2002 Russell King
- #
- MKIMAGE := $(srctree)/scripts/mkuboot.sh
- ifneq ($(MACHINE),)
- include $(srctree)/$(MACHINE)/Makefile.boot
- endif
- # Note: the following conditions must always be true:
- # ZRELADDR == virt_to_phys(PAGE_OFFSET + TEXT_OFFSET)
- # PARAMS_PHYS must be within 4MB of ZRELADDR
- # INITRD_PHYS must be in RAM
- ZRELADDR := $(zreladdr-y)
- PARAMS_PHYS := $(params_phys-y)
- INITRD_PHYS := $(initrd_phys-y)
- export ZRELADDR INITRD_PHYS PARAMS_PHYS
- targets := Image zImage xipImage bootpImage uImage
- ifeq ($(CONFIG_XIP_KERNEL),y)
- $(obj)/xipImage: vmlinux FORCE
- $(call if_changed,objcopy)
- @echo ' Kernel: $@ is ready (physical address: $(CONFIG_XIP_PHYS_ADDR))'
- $(obj)/Image $(obj)/zImage: FORCE
- @echo 'Kernel configured for XIP (CONFIG_XIP_KERNEL=y)'
- @echo 'Only the xipImage target is available in this case'
- @false
- else
- $(obj)/xipImage: FORCE
- @echo 'Kernel not configured for XIP (CONFIG_XIP_KERNEL!=y)'
- @false
- $(obj)/Image: vmlinux FORCE
- $(call if_changed,objcopy)
- @echo ' Kernel: $@ is ready'
- $(obj)/compressed/vmlinux: $(obj)/Image FORCE
- $(Q)$(MAKE) $(build)=$(obj)/compressed $@
- $(obj)/zImage: $(obj)/compressed/vmlinux FORCE
- $(call if_changed,objcopy)
- @echo ' Kernel: $@ is ready'
- endif
- 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 {1}lt; $@
- ifeq ($(CONFIG_ZBOOT_ROM),y)
- $(obj)/uImage: LOADADDR=$(CONFIG_ZBOOT_ROM_TEXT)
- else
- $(obj)/uImage: LOADADDR=$(ZRELADDR)
- endif
- $(obj)/uImage: STARTADDR=$(LOADADDR)
- $(obj)/uImage: $(obj)/zImage FORCE
- $(call if_changed,uimage)
- @echo ' Image $@ is ready'
- $(obj)/bootp/bootp: $(obj)/zImage initrd FORCE
- $(Q)$(MAKE) $(build)=$(obj)/bootp $@
- @:
- $(obj)/bootpImage: $(obj)/bootp/bootp FORCE
- $(call if_changed,objcopy)
- @echo ' Kernel: $@ is ready'
- PHONY += initrd FORCE
- initrd:
- @test "$(INITRD_PHYS)" != "" || \
- (echo This machine does not support INITRD; exit -1)
- @test "$(INITRD)" != "" || \
- (echo You must specify INITRD; exit -1)
- install: $(obj)/Image
- $(CONFIG_SHELL) $(srctree)/$(src)/install.sh $(KERNELRELEASE) \
- $(obj)/Image System.map "$(INSTALL_PATH)"
- zinstall: $(obj)/zImage
- $(CONFIG_SHELL) $(srctree)/$(src)/install.sh $(KERNELRELEASE) \
- $(obj)/zImage System.map "$(INSTALL_PATH)"
- zi:
- $(CONFIG_SHELL) $(srctree)/$(src)/install.sh $(KERNELRELEASE) \
- $(obj)/zImage System.map "$(INSTALL_PATH)"
- i:
- $(CONFIG_SHELL) $(srctree)/$(src)/install.sh $(KERNELRELEASE) \
- $(obj)/Image System.map "$(INSTALL_PATH)"
- subdir- := bootp compressed
|
评论暂时关闭