作者：华清远见嵌入式学院。《Linux设备驱动开发详解》（08&09年度畅销榜TOP50）第8章、Linux设备驱动中的阻塞与非阻塞I/O。阻塞和非阻塞I/O是设备访问的两种不同模式，驱动程序可以灵活地支持用户空间对设备的这两种访问方式。8.1节讲解阻塞I/O和非阻塞I/O的区别，实现阻塞I/O的等待队列机制，以及在globalfifo设备驱动中增加对阻塞I/O支持的方法，并进行了用户空间的验证。8.2节讲解设备驱动的轮询（poll）操作的概念和编程方法，poll操作可以帮助用户了解是否能对设备进行无阻塞访问。8.3节讲解在globalfifo中增加poll操作的方法，并进行了用户空间的验证。-Author: HuaQing vision embedded institute. The Linux device driver development "(08 and 09 sep TOP50) annual list of best-selling chapter 8, Linux device driver of clogging with the jam the I/O. Jam and the jam the I/O is device access two kinds of different pattern, the driver can the flexibility to support the user space on the equipment the two access method. Section 8.1 explain jam the I/O and the jam the I/O distinction, realize jam I/O wait queue mechanism, and in globalfifo device driver to increase in blocking the I/O support method, and the user space validation. Section 8.2 explain device driver polling (poll) operation concept and programming method, and can help users understand the poll operation of equipment is no block access. Section 8.3 in globalfifo explain in poll operate method, increase and the user space validation.