{"id":1439,"date":"2010-09-24T16:03:12","date_gmt":"2010-09-24T08:03:12","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=1439"},"modified":"2010-10-27T20:32:08","modified_gmt":"2010-10-27T12:32:08","slug":"%e5%ad%97%e7%ac%a6%e8%ae%be%e5%a4%87%e9%a9%b1%e5%8a%a8%e5%88%86%e6%9e%902","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/1439","title":{"rendered":"\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\u5206\u6790(2)"},"content":{"rendered":"

\u5728\u524d\u6587<\/a>\u4e2d\uff0c\u6211\u4eec\u6309\u7167\u4e00\u822c\u5185\u6838\u6a21\u5757\u7684\u7ed3\u6784\u5206\u6790\u4e86globalmem_init\u51fd\u6570\u548cglobalmem_exit\u51fd\u6570\u3002\u901a\u8fc7\u4e0a\u8ff0\u4e24\u4e2a\u51fd\u6570\u53ef\u4ee5\u5b8c\u6210\u5b57\u7b26\u9a71\u52a8\u7684\u52a0\u8f7d\u548c\u5378\u8f7d\u3002\u90a3\u4e48\u672c\u6587\u5c06\u8fdb\u4e00\u6b65\u5206\u6790\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\u7684\u5b9e\u73b0\u3002<\/p>\n

linux2.6\u5185\u6838\u4e2d\u4f7f\u7528cdev\u7ed3\u6784\u4f53\u6765\u8868\u8ff0\u4e00\u4e2a\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\uff0c\u4f46\u662f\u4e00\u822c\u6211\u4eec\u5e76\u4e0d\u76f4\u63a5\u4f7f\u7528cdev\u7ed3\u6784\u4f53\uff0c\u800c\u662f\u5c06\u4e0e\u8be5\u8bbe\u5907\u76f8\u5173\u7684\u4fe1\u606f\u4e0ecdev\u8857\u5934\u4f53\u7ed3\u5408\u7231\u4e00\u8d77\uff0c\u5b9a\u4e49\u4e00\u4e2a\u65b0\u7684\u7ed3\u6784\u4f53\uff0c\u6bd4\u5982<\/p>\n

struct globalmem_dev\r\n{    struct cdev cdev;\r\n      unsigned char mem[GLOBALMEM_SIZE];\r\n};\r\nstruct cdev\r\n{\r\n\tstruct kobject kobj;\/\/\u5185\u5d4ckobject\u5bf9\u8c61\r\n\tstruct module *owner;\/\/\u6307\u5411\u5b9e\u73b0\u9a71\u52a8\u7a0b\u5e8f\u7684\u6a21\u5757\u7684\u6307\u9488\uff0c\u901a\u5e38\u4e3aTHIS_MODULE\r\n\tconst struct file_operations *ops;\/\/\u6307\u5411\u6b64\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u6587\u4ef6\u64cd\u4f5c\u7ed3\u6784\u4f53\u7684\u6307\u9488\r\n\tstruct list_head list;\/\/\u6307\u5411\u5b57\u7b26\u8bbe\u5907\u6587\u4ef6\u5bf9\u5e94\u7684\u7d22\u5f15\u8282\u70b9\u94fe\u8868\u7684\u5934\r\n\tdev_t dev;\/\/\u8bbe\u5907\u53f7\r\n\tunsigned int count;\/\/\u7ed9\u8be5\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u5206\u914d\u7684\u8bbe\u5907\u53f7\u8303\u56f4\u7684\u5927\u5c0f\r\n};<\/pre>\n
\u5c31\u50cf\u524d\u6587\u6240\u8bf4\u7684\uff0c\u8bbe\u5907\u53f7\u90fd\u662f\u5206\u914d\u4e00\u4e2a\u8303\u56f4\uff08count\u7684\u5927\u5c0f\uff09\uff0c\u56e0\u6b64\u53ef\u80fd\u6709\u5f88\u591a\u4e2a\u8bbe\u5907\u6587\u4ef6\u4e3b\u8bbe\u5907\u53f7\u76f8\u540c\u5e76\u4e14\u5bf9\u5e94\u4e8e\u540c\u4e00\u4e2a\u8bbe\u5907\u9a71\u52a8\u3002list\u6240\u6307\u5411\u7684\u94fe\u8868\u5c31\u662f\u7531\u5f53\u524d\u8be5\u8bbe\u5907\u9a71\u52a8\u5bf9\u5e94\u7684\u8bbe\u5907\u6587\u4ef6\u7d22\u5f15\u8282\u70b9\u7ec4\u6210\u3002<\/p>\n
\u6211\u4eec\u73b0\u5728\u56de\u5230globalmem_setup_cdev\u51fd\u6570\uff0c\u5b83\u7684\u4e3b\u8981\u4f5c\u7528\u5c31\u662f\u7533\u8bf7\u5e76\u521d\u59cb\u5316\u4e00\u4e2acdev\u7ed3\u6784\u4f53\uff0c\u5e76\u4e14\u5c06\u901a\u8fc7cdev_add\u51fd\u6570\u5411\u7cfb\u7edf\u5185\u6dfb\u52a0\u4e00\u4e2acdev\uff0c\u5b8c\u6210\u5b57\u7b26\u8bbe\u5907\u7684\u6ce8\u518c\u3002\u901a\u5e38\u6211\u4eec\u5c06cdev_add\u51fd\u6570\u5b89\u6392\u5728\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\u6a21\u5757\u7684\u52a0\u8f7d\u51fd\u6570\u4e2d\uff0c\u800c\u5bf9\u5e94\u7684\u5c06cdev_del\u51fd\u6570\u653e\u5728\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\u7684\u5378\u8f7d\u51fd\u6570\u4e2d\u3002<\/p>\n
static void globalmem_setup_cdev(struct globalmem_dev *dev, int index)\r\n{\r\nint err, devno = MKDEV(globalmem_major, index);\r\n\r\ncdev_init(&dev->cdev, &globalmem_fops);\r\ndev->cdev.owner = THIS_MODULE;\r\ndev->cdev.ops = &globalmem_fops;\r\nerr = cdev_add(&dev->cdev, devno, 1);\r\nif (err)\r\nprintk(KERN_NOTICE \"Error %d adding cdev%d\", err, index);\r\n}<\/pre>\n
\u9664\u6b64\u4e4b\u5916\uff0cglobalmem_setup_cdev\u51fd\u6570\u8fd8\u4f1a\u5c06cdev\u7ed3\u6784\u4f53\u4e2d\u7684struct file_operation\u7c7b\u578b\u7684\u6307\u9488ops\u5b9e\u4f8b\u5316\u3002globalmem_fops\u5168\u5c40\u53d8\u91cf\u662f\u6587\u4ef6\u64cd\u4f5c\u8868\uff0c\u8fd9\u4e2a\u7ed3\u6784\u4e2d\u542b\u6709\u8bb8\u591a\u6587\u4ef6\u64cd\u4f5c\u51fd\u6570\u7c7b\u578b\u7684\u6307\u9488\u3002\u5f53\u6211\u4eec\u5b9e\u73b0\u67d0\u4e9b\u6587\u4ef6\u64cd\u4f5c\u51fd\u6570\u65f6\uff0c\u5c31\u53ef\u4ee5\u5c06\u8fd9\u4e9b\u51fd\u6570\u540d\u8d4b\u503c\u7ed9\u8fd9\u4e2a\u7ed3\u6784\u4e2d\u7684\u76f8\u5e94\u53d8\u91cf\u3002\u6bd4\u5982\u6211\u4eec\u5728\u7a0d\u5019\u4f1a\u5b9e\u73b0globalmem_open\u51fd\u6570\uff0c\u5c06\u5176\u8d4b\u503c\u7ed9globalmem.open\uff0c\u90a3\u4e48\u5f53\u7528\u6237\u4f7f\u7528open\u7cfb\u7edf\u8c03\u7528\u5bf9\u5b57\u7b26\u8bbe\u5907\u6587\u4ef6\u8fdb\u884c\u6253\u5f00\u64cd\u4f5c\u65f6\uff0c\u5185\u6838\u5c31\u4f1a\u81ea\u52a8\u8c03\u7528\u9002\u5408\u8be5\u8bbe\u5907\u6587\u4ef6\u7684\u6253\u5f00\u51fd\u6570\uff0c\u4e5f\u5c31\u662fglobalmem_open\u51fd\u6570\u3002<\/p>\n
\u6b63\u5982\u4f60\u6240\u77e5\u7684\u90a3\u6837\uff0cLinux\u4e0b\u4e00\u4e9b\u7686\u4e3a\u6587\u4ef6\uff0c\u5f53\u7136\u8bbe\u5907\u4e5f\u4e0d\u4f8b\u5916\u3002\u5bf9\u4e8e\u4e00\u4e2a\u8bbe\u5907\u6587\u4ef6\u6765\u8bf4\uff0c\u7528\u6237\u901a\u8fc7VFS\u53ef\u4ee5\u4f7f\u7528\u7edf\u4e00\u7684\u7cfb\u7edf\u8c03\u7528\u63a5\u53e3\u5bf9\u5404\u79cd\u8bbe\u5907\uff08\u6587\u4ef6\uff09\u8fdb\u884c\u76f8\u5173\u64cd\u4f5c\uff0c\u6bd4\u5982open\uff0cread\uff0cwrite\u7b49\u7b49\uff0c\u7528\u6237\u53ef\u4ee5\u4e0d\u53bb\u8003\u8651\u5f53\u524d\u8bbe\u5907\u5177\u4f53\u5982\u4f55\u53bb\u64cd\u4f5c\u3002\u800c\u5728VFS\u5c42\u4e0b\u2014\u2014\u4f4d\u4e8e\u64cd\u4f5c\u7cfb\u7edf\u4e2d\u7684\u8bbe\u5907\u9a71\u52a8\u5c31\u4f1a\u5bf9\u4e8e\u6bcf\u79cd\u8bbe\u5907\u53bb\u5b9e\u73b0\u76f8\u5e94\u7684\u64cd\u4f5c\u51fd\u6570\u3002\u5bf9\u4e8e\u6bcf\u7c7b\u8bbe\u5907\u6240\u5b9e\u73b0\u7684\u64cd\u4f5c\u5982\u4f55\u5728\u7528\u6237\u5c42\u7edf\u4e00\u7684\u8868\u73b0\u51fa\u6765\uff0c\u8fd9\u5c31\u9700\u8981struct file_operations\u7ed3\u6784\u4f53\u3002\u6b64\u7ed3\u6784\u4f53\u4e2d\u5305\u542b\u5927\u91cf\u7684\u51fd\u6570\u6307\u9488\uff0c\u8fd9\u4e9b\u51fd\u6570\u6307\u9488\u4fbf\u662f\u7528\u6237\u5c42\u4e0a\u7edf\u4e00\u7684\u7cfb\u7edf\u8c03\u7528\u51fd\u6570\u540d\uff0c\u5c06\u8bbe\u5907\u9a71\u52a8\u4e2d\u5b9e\u73b0\u7684\u5177\u4f53\u64cd\u4f5c\u51fd\u6570\u8d4b\u503c\u7ed9\u8fd9\u4e9b\u51fd\u6570\u6307\u9488\u540e\uff0c\u7528\u6237\u5c31\u53ef\u4ee5\u4f7f\u7528\u7edf\u4e00\u7684\u7cfb\u7edf\u8c03\u7528\u51fd\u6570\u4e86\u3002<\/p>\n
\u63a5\u4e0b\u6765\u6211\u4eec\u6765\u770b\u5177\u4f53\u7684\u6587\u4ef6\u64cd\u4f5c\u51fd\u6570\u662f\u5982\u4f55\u5b9e\u73b0\u7684\u3002
\n\u6587\u4ef6\u6253\u5f00\u51fd\u6570\u5c06\u8bbe\u5907\u7ed3\u6784\u4f53\u6307\u9488\u8d4b\u503c\u7ed9\u79c1\u6709\u6570\u636e\uff0c\u8fd9\u4e2a\u79c1\u6709\u6570\u636e\u4f1a\u5728\u7a0d\u5019\u7684read\u4ee5\u53cawrite\u4e2d\u88ab\u7528\u5230\uff0c\u800c\u4e0d\u662f\u76f4\u63a5\u7684\u4f7f\u7528globalmem_devp\u3002<\/p>\n
\/*\u6587\u4ef6\u6253\u5f00\u51fd\u6570*\/\r\nint globalmem_open(struct inode *inode, struct file *filp)\r\n{\r\n  \/*\u5c06\u8bbe\u5907\u7ed3\u6784\u4f53\u6307\u9488\u8d4b\u503c\u7ed9\u6587\u4ef6\u79c1\u6709\u6570\u636e\u6307\u9488*\/\r\n  filp->private_data = globalmem_devp;\r\n  return 0;\r\n}<\/pre>\n
\u5728\u8bfb\u51fd\u6570\u4e2d\uff0c\u9996\u5148\u5c06\u79c1\u6709\u6570\u636e\u8d4b\u503c\u7ed9\u4e00\u4e2a\u8bbe\u5907\u7ed3\u6784\u4f53\u6307\u9488\u3002\u7136\u540e\uff0c\u5224\u65ad\u8981\u8bfb\u7684\u957f\u5ea6\u662f\u5426\u5408\u6cd5\u3002\u63a5\u7740\u5229\u7528copy_to_user\u51fd\u6570\u5185\u6838\u7a7a\u95f4\u7684\u6570\u636e\uff08dev->mem\uff09\u62f7\u8d1d\u5230\u7528\u6237\u7a7a\u95f4\u3002\u5173\u4e8e\u8fd9\u4e2acopy_to_user\u51fd\u6570\u7684\u8be6\u7ec6\u62f7\u8d1d\u8fc7\u7a0b\uff0c\u6211\u4eec\u4e5f\u53ef\u4ee5\u5bf9\u5176\u8fdb\u884c\u4ee3\u7801\u5206\u6790\u3002\u5982\u679c\u62f7\u8d1d\u6210\u529f\uff0c\u90a3\u4e48\u4fee\u6539\u76f8\u5e94\u7684\u6307\u9488\u5373\u53ef\u5b8c\u6bd5\u8bfb\u64cd\u4f5c\u3002<\/p>\n
\/*\u8bfb\u51fd\u6570*\/\r\nstatic ssize_t globalmem_read(struct file *filp, char __user *buf, size_t size,\r\n  loff_t *ppos)\r\n{\r\n  unsigned long p =  *ppos;\r\n  unsigned int count = size;\r\n  int ret = 0;\r\n  struct globalmem_dev *dev = filp->private_data; \/*\u83b7\u5f97\u8bbe\u5907\u7ed3\u6784\u4f53\u6307\u9488*\/\r\n\r\n  \/*\u5206\u6790\u83b7\u53d6\u6709\u6548\u7684\u5199\u957f\u5ea6*\/\r\n  if (p >= GLOBALMEM_SIZE)\r\n    return count ?  - ENXIO: 0;\r\n  if (count > GLOBALMEM_SIZE - p)\r\n    count = GLOBALMEM_SIZE - p;\r\n\r\n  \/*\u4ece\u5185\u6838\u7a7a\u95f4\u5411\u7528\u6237\u7a7a\u95f4\u5199\u6570\u636e*\/\r\n  if (copy_to_user(buf, (void*)(dev->mem + p), count))\r\n  {\r\n    ret =  - EFAULT;\r\n  }\r\n  else\r\n  {\r\n    *ppos += count;\r\n    ret = count;\r\n\r\n    printk(KERN_INFO \"read %d bytes(s) from %d\\n\", count, p);\r\n  }\r\n\r\n  return ret;\r\n}<\/pre>\n
\u5199\u51fd\u6570\u4e0e\u8bfb\u51fd\u6570\u7684\u8fc7\u7a0b\u5927\u4f53\u4e00\u76f4\uff0c\u4e0d\u540c\u7684\u662f\u4f7f\u7528\u4e86copy_from_user\u51fd\u6570\u3002\u8fd9\u91cc\u4e0d\u518d\u8be6\u89e3\u3002<\/p>\n
\u63a5\u4e0b\u6765\u6211\u4eec\u5c31\u53ef\u4ee5\u4f7f\u7528\u4e00\u4e2a\u7b80\u5355\u6d4b\u8bd5\u7a0b\u5e8f\u6765\u5bf9\u6211\u4eec\u6240\u5b9e\u73b0\u7684\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\u8fdb\u884c\u6d4b\u8bd5\u4e86\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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