Code samples of how to map the memory allocated in the kernel mode to the user mode.

nopage 方式的内存映射机制，完成用户空间和内核空间间的地址转化，多用户空间的数据交换，已通过测试。-memory mapping mechanism for nopage way to complete the address conversion between user space and kernel space, the space of multi-user data exchange, has been tested.