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用内存代替块设备的总结,相对来简单得多，对内存操作想必大家都很熟悉，直接分配一块内存就可以直接读写操作了 /* 参考: * drivers\block\xd.c * drivers\block\z2ram.c */ #define RAMBLOCK_SIZE (1024*1024)//一个扇区是512字节 static struct gendisk *ramblock_disk; static struct request_queue *ramblock_queue; static DEFINE_SPINLOCK(ramblock_lock);//定义一个自旋锁 static unsigned char *ramblock_buf; static struct block_device_operations ramblock_fops = {//fops结构体，必须要。.owner = THIS_MODULE,.getgeo = ramblock_getgeo,//设置heads /cylinders/sectors }; static int ramblock_getgeo(struct block_device *bdev, struct hd_geometry *geo) { /* 容量=heads*cylinders*sectors*512 */geo->heads = 2;//柱头geo->cylinders = 32;//柱面geo->sectors = RAMBLOCK_SIZE/2/32/512;//扇区return 0; } static int ramblock_init(void) { /* 1. 分配一个gendisk结构体 */ramblock_disk = alloc_disk(16); /* 次设备号个数: 分区个数+1 *//* 2. 设置 *//* 2.1 分配/设置队列: 提供读写能力 */ramblock_queue = blk_init_queue(do_ramblock_request, &ramblock_lock);//do_ramblock_request请求队列函数ramblock_disk->queue = ramblock_queue;/* 2.2 设置其他属性: 比如容量 */major = register_blkdev(0, "ramblock"); /* cat /proc/devices */ramblock_disk->major = major;ramblock_disk->first_minor = 0;sprintf(ramblock_disk->disk_name, "ramblock");//把ramblock打印到ramblock_disk->disk_nameramblock_disk->fops = &ramblock_fops;set_capacity(ramblock_disk, RAMBLOCK_SIZE / 512);//设置容量. 硬件相关操作 */ramblock_buf = kzalloc(RAMBLOCK_SIZE, GFP_KERNEL);//分配一个读写缓冲区/* 4. 注册 */add_disk(ramblock_disk); } static void do_ramblock_request(struct request_queue * q)//当读写的时候调用这个函数 { static int r_cnt = 0;static int w_cnt = 0;struct request *req;//printk("do_ramblock_request %d\n", ++cnt); while ((req = elv_next_request(q)) != NULL) { /* 数据传输三要素: 源,目的,长度 *//* 源/目的: */unsigned long offset = req->sector * 512;//偏移值为 /* 目的/源: */// req->buffer /* 长度: */ unsigned long len = req->current_nr_sectors * 512; if (rq_data_dir(req) == READ){ //printk("do_ramblock_request read %d\n", ++r_cnt);memcpy(req->buffer, ramblock_buf+offset, len);}else{ //printk("do_ramblock_request write %d\n", ++w_cnt);memcpy(ramblock_buf+offset, req->buffer, len);} end_request(req, 1);//表示读写完成，必须写，不然会卡在那里，只有重新开关机} } } static void ramblock_exit(void) { unregister_blkdev(major, "ramblock");del_gendisk(ramblock_disk);put_disk(ramblock_disk);blk_cleanup_queue(ramblock_queue); kfree(ramblock_buf); } 测试如下： 在开发板上: 1. insmod ramblock.ko 2. 格式化: mkdosfs /dev/ramblock 3. 挂接: mount /dev/ramblock /tmp/ 4. 读写文件: cd /tmp, 在里面vi文件 5. cd /; umount /tmp/ 6. cat /dev/ramblock > /mnt/ramblock.bin 7. 在PC上查看ramblock.bin sudo mount -o loop ramblock.bin /mnt 测试5th: 1. insmod ramblock.ko 2. ls /dev/ramblock* 3. fdisk /dev/ramblock 块设备常用的几个命令： m：寻求帮助 n：增加一个新的分区 w:保存分区 转载地址：http://mgxkm.baihongyu.com/