内核初始化：init/mainc之blk_dev_init(); chr_dev_init();

blk_dev_init()的代码很少，如下：
void blk_dev_init(void)
{       
        int i;
        
        for (i=0 ; i                 request[i].dev = -1;
                request[i].next = NULL;
        }

其中#define NR_REQUEST      32

struct request request[NR_REQUEST];
struct request {
        int dev;                /* -1 if no request */
        int cmd;                /* READ or WRITE */
        int errors;
        unsigned long sector;
        unsigned long nr_sectors;
        char * buffer;
        struct task_struct * waiting;
        struct buffer_head * bh;
        struct request * next;
};
可见这程序是对块设备进行初始化；
 request[i].dev = -1;
  request[i].next = NULL;

将设备设置为空闲，参见http://82117575.blog.163.com/blog/static/13722000820100315244574/

chr_dev_init();什么也没有做