学习中的一些问题【To be continue】

1、为什么驱动程序中有很多函数前要加上static ？

因为内核中很多函数都是可能重名的，而函数默认为extern形式，所以尽量需要将本文件内使用的函数加上static，防止引用函数时出错。

2、用户空间
User space is system memory allocated to running applications. It is often contrasted with kernel space, which is memory allocated to the kernel and the operating system. Separating user space from kernel space protects the system from errant processes that could use up memory required by the operating system (OS).

3、uImage 和 zImage 的区别

After the kernel compiles (make), it will generate two files, an Image, a zImage, where Image is the kernel image file, and zImage is an image compression file of the kernel. Image is about 4M, and zImage is less than 2M.
So what is uImage? It is a uboot-specific image file. It adds a 64-byte "header" before the zImage, indicating the version, loading position, generation time, size, etc. of the kernel; it is no different from zImage after 0x40.