linux 内核 zImage 生成过程分析

1. 依据arch/arm/kernel/vmlinux.lds 生成linux内核源码根目录下的vmlinux，这个vmlinux属于未压缩，带调试信息、符号表的最初的内核，大小约23MB； 
arm-linux-gnu-ld -EL  -p --no-undefined -X -o vmlinux -T arch/arm/kernel/vmlinux.lds

arch/arm/kernel/head.o  
arch/arm/kernel/init_task.o   
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/nwfpe/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   
lib/lib.a   
arch/arm/lib/lib.a   
lib/built-in.o   
arch/arm/lib/built-in.o   
drivers/built-in.o   
sound/built-in.o   
net/built-in.o  
--end-group .tmp_kallsyms2.o 
2. 将上面的vmlinux去除调试信息、注释、符号表等内容，生成arch/arm/boot/Image，这是不带多余信息的linux内核，Image的大小约3.2MB； 
命令:arm-linux-gnu-objcopy -O binary -R .note -R .comment -S  vmlinux arch/arm/boot/Image 
3. 将 arch/arm/boot/Image 用gzip -9 压缩生成arch/arm/boot/compressed/piggy.gz大小约1.5MB； 
命令:gzip -f -9 < arch/arm/boot/compressed/../Image > arch/arm/boot/compressed/piggy.gz
4. 编译arch/arm/boot/compressed/piggy.S 生成arch/arm/boot/compressed/piggy.o大小约1.5MB，这里实际上是将piggy.gz通过piggy.S编译进piggy.o文件中。而piggy.S文件仅有6行，只是包含了文件piggy.gz; 
 命令:arm-linux-gnu-gcc -Wp,-MD,arch/arm/boot/compressed/.piggy.o.d  -nostdinc -isystem /home/justin/crosstool/gcc-3.4.5-glibc-2.3.6/arm-linux-gnu/lib/gcc/arm-linux-gnu/3.4.5/include -D__KERNEL__ -Iinclude  -mlittle-endian -D__ASSEMBLY__ -Wa,-L -gdwarf-2 -mapcs-32 -mno-thumb-interwork -D__LINUX_ARM_ARCH__=4 -march=armv4 -mtune=arm9tdmi -msoft-float    -c -o arch/arm/boot/compressed/piggy.o arch/arm/boot/compressed/piggy.S 
5. 依据arch/arm/boot/compressed/vmlinux.lds 将arch/arm/boot/compressed/目录下的文件head.o 、piggy.o 、misc.o链接生成 arch/arm/boot/compressed/vmlinux，这个vmlinux是经过压缩且含有自解压代码的内核,大小约1.5MB; 
命令:arm-linux-gnu-ld -EL   --defsym zreladdr=0x30008000 --defsym params_phys=0x30000100 -p --no-undefined -X /home/justin/crosstool/gcc-3.4.5-glibc-2.3.6/arm-linux-gnu/lib/gcc/arm-linux-gnu/3.4.5/libgcc.a -T arch/arm/boot/compressed/vmlinux.lds arch/arm/boot/compressed/head.o arch/arm/boot/compressed/piggy.o arch/arm/boot/compressed/misc.o -o arch/arm/boot/compressed/vmlinux 
6. 将arch/arm/boot/compressed/vmlinux去除调试信息、注释、符号表等内容，生成arch/arm/boot/zImage大小约1.5MB;这已经是一个可以使用的linux内核映像文件了； 
命令:arm-linux-gnu-objcopy -O binary -R .note -R .comment -S  arch/arm/boot/compressed/vmlinux arch/arm/boot/zImage 
7. 将arch/arm/boot/zImage添加64Bytes的相关信息打包为arch/arm/boot/uImage大小约1.5MB; 
命令:/bin/sh /home/farsight/Resources/kernel/linux-2.6.14/scripts/mkuboot.sh -A arm -O linux -T kernel -C none -a 0x30008000 -e 0x30008000 -n 'Linux-2.6.14' -d arch/arm/boot/zImage arch/arm/boot/uImage

本文转自：http://blog.chinaunix.net/uid-2630593-id-2530229.html