target/linux/ramips/Makefile: $(eval $(call BuildTarget))
target/linux/Makefile : export TARGET_BUILD=1
include/target.mk:
include $(INCLUDE_DIR)/kernel.mk
ifeq ($(TARGET_BUILD),1)
include $(INCLUDE_DIR)/kernel-build.mk
BuildTarget?=$(BuildKernel)
endif
BuildKernel是include/kernel-build.mk定义的一个多行变量,其中描述了如何编译内核, 主要关注其中install规则的依赖链:
$(KERNEL_BUILD_DIR)/symtab.h: FORCE
rm -f $(KERNEL_BUILD_DIR)/symtab.h
touch $(KERNEL_BUILD_DIR)/symtab.h
+$(MAKE) $(KERNEL_MAKEOPTS) vmlinux
... $(LINUX_DIR)/.image: $(STAMP_CONFIGURED) $(if $(CONFIG_STRIP_KERNEL_EXPORTS),$(KERNEL_BUILD_DIR)/symtab.h) FORCE $(Kernel/CompileImage) $(Kernel/CollectDebug)
touch $$@
install: $(LINUX_DIR)/.image +$(MAKE) -C image compile install TARGET_BUILD=
1. 触发make vmlinux命令生成vmlinux: install --> $(LINUX_DIR)/.image --> $(KERNEL_BUILD_DIR)/symtab.h --> `$(MAKE) $(KERNEL_MAKEOPTS) vmlinux`
2. 对vmlinux做objcopy, strip操作:
$(LINUX_DIR)/.image
--> $(Kernel/CompileImage) --> $(call Kernel/CompileImage/Default) --> $(call Kernel/CompileImage/Default) $(KERNEL_CROSS)objcopy -O binary $(OBJCOPY_STRIP) -S $(LINUX_DIR)/vmlinux
$(LINUX_KERNEL)$(1)
--> build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620a/vmlinux $(KERNEL_CROSS)objcopy $(OBJCOPY_STRIP) -S $(LINUX_DIR)/vmlinux $(KERNEL_BUILD_DIR)/vmlinux$(1).elf
--> build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620a/vmlinux.elf $(CP) $(LINUX_DIR)/vmlinux $(KERNEL_BUILD_DIR)/vmlinux.debug
--> build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620a/vmlinux.debug