static int __init memdev_init(void)  
{  
         int result;  
         int err;  
         int i;  
          
         //申请设备号  
         dev_t devno = MKDEV(251, 0);  
          
         if(mem_major)  
                   result= register_chrdev_region(devno, MEMDEV_NUM, "memdev");//注意静态申请的dev_t参数和动态dev_t参数的区别  
         else{        //静态直接传变量，动态传变量指针  
                   result= alloc_chrdev_region(&devno, 0, MEMDEV_NUM, "memdev");  
                   mem_major= MAJOR(devno);  
         }  
          
         if(result< 0){  
                   printk("can'tget major devno:%d\n", mem_major);  
                   returnresult;  
         }