我正在用drivers/char/new_driver.c
编写内核驱动程序。此新驱动程序通过调用 API 注册两个新设备/dev/device1
和/dev/device2
misc_register()
。
error = misc_register(&device1);
error = misc_register(&device2);
static struct miscdevice device1 = {
MISC_DYNAMIC_MINOR,
"device1",
&device1_fops
};
static struct miscdevice device2 = {
MISC_DYNAMIC_MINOR,
"device2",
&device2_fops
};
当我加载模块时,我看到 2 两个设备在 /dev/device1
和 /dev/device2
中正确创建
但是当我尝试在此设备上write/read
操作时,它会给出错误,说"没有这样的设备"。
知道是什么原因导致这种类型的错误吗? 驱动程序代码中缺少任何内容?
我仍然认为这是权限问题。我正在附加示例代码(没有任何实际实现(骨架。请看一看。
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/module.h>
static int sample_open(struct inode *inode, struct file *file)
{
pr_info("Maverick: %s func :n",__func__);
return 0;
}
static int sample_close(struct inode *inodep, struct file *filp)
{
pr_info("Maverick: %s func :n",__func__);
return 0;
}
static ssize_t sample_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos)
{
pr_info("Maverick: %s func :n",__func__);
return len; /* Not doing anything with the data */
}
static ssize_t sample_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
pr_info("Maverick: %s func :n",__func__);
return len; /* Not do anything with the data */
}
static const struct file_operations sample_fops = {
.owner = THIS_MODULE,
.write = sample_write,
.read = sample_read,
.open = sample_open,
.release = sample_close,
};
struct miscdevice sample_device = {
.minor = MISC_DYNAMIC_MINOR,
.name = "device1",
.fops = &sample_fops,
};
static int __init misc_init(void)
{
int error;
error = misc_register(&sample_device);
if (error) {
pr_err("can't misc_register :(n");
return error;
}
pr_info("Maverick: %s func :n",__func__);
return 0;
}
static void __exit misc_exit(void)
{
misc_deregister(&sample_device);
pr_info("Maverick: %s func :n",__func__);
}
module_init(misc_init)
module_exit(misc_exit)
MODULE_DESCRIPTION("Sample Misc Driver");
MODULE_AUTHOR("Vinod Maverick <vinodmaverickr007@gmail.com>");
MODULE_LICENSE("GPL");
然后编译驱动程序:
make
sudo insmod misc_sample.ko
ilab@SSID-iLBPG3:~/vinod/ldd$ echo "hello" > /dev/device1
-bash: /dev/device1: Permission denied
ilab@SSID-iLBPG3:~/vinod/ldd$ sudo su
root@SSID-iLBPG3:/home/ilab/vinod/ldd# echo "hello" > /dev/device1
但是我在读/写回调中没有任何代码,但您仍然可以看到 dmesg 而没有任何错误
root@SSID-iLBPG3:/home/ilab/vinod/ldd# dmesg
[2903599.416005] Maverick: misc_init func :
[2903623.966281] Maverick: sample_open func :
[2903623.966292] Maverick: sample_write func :
[2903623.966295] Maverick: sample_close func :
root@SSID-iLBPG3:/home/ilab/vinod/ldd#
对于仍然有此问题的任何人,我设法通过将我的次要号码从疯狂的高数字 (999( 更改为更合理的数字 (71( 来修复它。这是我生成的杂项设备结构:
static struct miscdevice chrdev = {
.minor = 71,
.name = "tracefunc",
.fops = &chrdev_fops,
.mode = S_IRUGO,
};