1) diff/patch这对工具在数学上来说，diff是对2个集合求差，patch是求和
diff A B > C 生成A和B的diff文件C
patch A C 给A打上diff文件得到B
patch -R B C B还原为A
2) 内核补丁
生成
diff -uNr linux-2.6.xxx linux-2.6.xxx.1 > diff.patch
升级
cp diff.patch linux-2.6.xxx/.
cd linux-2.6.xxx
patch -p1 < diff.patch
可以参考$(linux_src)/Documentation/applying_patches.txt