一般来说，我们个人开发都会利用上游芯片厂商提供的配套开发的交叉编译工具链，这样保证和原厂使用的是同一套环境，能够避免很多不必要的麻烦，但是经常遇到老版本的内核原厂官方不在支持，但是我们又有升级内核的需要，这个时候只能自己动手解决了，一般情况下所移植的内核在readme文件中有提到编译该版本内核所需要的最低工具链版本号，可据此参考寻找合适的交叉编译工具链。
COMPILING the kernel:
- Make sure you have at least gcc 3.2 available.
For more information, refer to Documentation/Changes.**
Please note that you can still run a.out user programs with this kernel.
- Do a "make" to create a compressed kernel image. It is also
possible to do "make install" if you have lilo installed to suit the
kernel makefiles, but you may want to check your particular lilo setup first.
To do the actual install, you have to be root, but none of the normal
build should require that. Don't take the name of root in vain.
- If you configured any of the parts of the kernel as `modules', you
will also have to do "make modules_install".
