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13章、Linux块设备驱动。块设备是与字符设备并列的概念，这两类设备在Linux中驱动的结构有较大差异，总体而言，块设备驱动比字符设备驱动要复杂得多，在I/O操作上表现出极大的不同，缓冲、I/O调度、请求队列等都是与块设备驱动相关的概念。本章将详细讲解Linux块设备驱动的编程方法。13.1节讲解块设备I/O操作的特点，分析字符设备与块设备在I/O操作上的差异。13.2节从整体上描述Linux块设备驱动的结构，分析主要的数据结构、函数及其关系。13.3～13.5节分别讲解块设备驱动模块加载与卸载、打开与释放和ioctl()函数。13.6节非常重要，讲述了块设备I/O操作所依赖的请求队列的概念及用法。13.2节与13.3～13.6节是整体与部分的关系，13.2～13.6节与13.7节是迭代递进的关系。13.7节在13.1～13.6节讲解内容的基础上，总结Linux下块设备的读写流程，而13.7节则讲解了块设备驱动的具体实例，即RamDisk的驱动。-Author: HuaQing vision embedded institute. The Linux device driver development "(08 and 09 sep TOP50) annual list of best-selling chapter 13, Linux piece of device drivers. Piece of equipment is the concept of equipment and characters are, these two types of equipment in the structure of the drive in Linux have bigger difference, overall, piece of equipment than character device drivers drive is much more complex, in the I/O operation borrows great different, buffer, I/O operation, request queuing is of the device driver related concepts. This chapter will be explained Linux piece of equipment of the driver programming. Section 13.1 explain piece of equipment I/O operation, the characteristics of the character device and piece of equipment analysis in the I/O operation differences. Section 13.2 from the whole descr iption of Linux device drivers, analysis of the main structure of the data structure, function and its relationship. 13.3 ~ 13.5 respectively of asher. Explain