内核启动流程分析之Makefile

分析Makefile：第一个文件、链接脚本

1、子目录下面的makefile：

obj-y += mem.o random.o tty_io.o n_tty.o tty_ioctl.o

obj-m += s3c24xx_leds.o

2、make uImage，发现uImage位于：linux-2.6.22.6_jz2440\linux-2.6.22.6\arch\arm\makefile

可以肯定上面的这个makefile会被包含在顶层的makefile里面,我们搜索顶层makefile发现里面有：include $(srctree)/arch/$(ARCH)/Makefile

在上一节的分析中，我们看到.config文件生成了autoconf.h和auto.conf

我们搜索一下顶层的makefile：-include include/config/auto.conf

在linux-2.6.22.6_jz2440\linux-2.6.22.6\arch\arm\makefile下可以看到uImage有关的一行：zImage Image xipImage bootpImage uImage: vmlinux，所以uImage依赖于vmlinux

在顶层makefile里面linux-2.6.22.6_jz2440\linux-2.6.22.6\makefile搜索vmlinux可以看到：all: vmlinux

zImage Image xipImage bootpImage uImage: vmlinux

vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) $(kallsyms.o) FORCE

vmlinux-init := $(head-y) $(init-y)

head-y := arch/arm/kernel/head$(MMUEXT).o arch/arm/kernel/init_task.o

init-y := init/

init-y := $(patsubst %/, %/built-in.o, $(init-y))即=init/built-in.o

vmlinux-main := $(core-y) $(libs-y) $(drivers-y) $(net-y)

core-y := usr/

core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/

core-y := $(patsubst %/, %/built-in.o, $(core-y))

=usr/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

libs-y := lib/

llibs-y1 := $(patsubst %/, %/lib.a, $(libs-y))

libs-y2 := $(patsubst %/, %/built-in.o, $(libs-y))

libs-y := $(libs-y1) $(libs-y2)

=lib/lib.a lib/built-in.o

drivers-y := drivers/ sound/

drivers-y := $(patsubst %/, %/built-in.o, $(drivers-y))

=drivers/built-in.o sound/built-in.o

net-y := net/

net-y := $(patsubst %/, %/built-in.o, $(net-y))

=net/built-in.o

vmlinux-all := $(vmlinux-init) $(vmlinux-main)

vmlinux-lds := arch/$(ARCH)/kernel/vmlinux.lds

走捷径分析linux：

book@book-desktop:/work/system/linux-2.6.22.6$ rm vmlinux

book@book-desktop:/work/system/linux-2.6.22.6$ make uImage V=1

arm-linux-ld -EL -p --no-undefined -X -o vmlinux

-T arch/arm/kernel/vmlinux.lds //链接脚本

arch/arm/kernel/head.o arch/arm/kernel/init_task.o //第一个文件，下面的都是原材料

init/built-in.o

--start-group usr/built-in.o arch/arm/kernel/built-in.o arch/arm/mm/built-in.o arch/arm/common/built-in.o

arch/arm/mach-s3c2410/built-in.o arch/arm/mach-s3c2400/built-in.o arch/arm/mach-s3c2412/built-in.o arch/arm/mach-s3c2440/built-in.o

arch/arm/mach-s3c2442/built-in.o arch/arm/mach-s3c2443/built-in.o arch/arm/nwfpe/built-in.o arch/arm/plat-s3c24xx/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 net/built-in.o --end-group .tmp_kallsyms2.o