IOCTL Linux设备驱动程序 [英] IOCTL Linux device driver

问题描述

谁能解释我，

1. 什么是IOCTL?
2. 它是用来干什么的?
3. 我如何使用它?
4. 为什么我不能定义与IOCTL相同功能的新函数?

1. What is IOCTL?
2. What is it used for?
3. How can I use it?
4. Why can't I define new function that does the same work as IOCTL?

推荐答案

一个ioctl，表示输入-输出控制"是一种特定于设备的系统调用. Linux(300-400)中只有很少的系统调用，不足以表达设备可能具有的所有独特功能.因此，驱动程序可以定义一个ioctl，该ioctl允许用户空间应用程序向其发送订单.但是，ioctl并不是很灵活，并且会变得有些混乱(数十个魔术数字"都可以正常工作...或不起作用)，并且在将缓冲区传递到内核时也可能是不安全的-错误的处理可能会破坏事情很容易.

An ioctl, which means "input-output control" is a kind of device-specific system call. There are only a few system calls in Linux (300-400), which are not enough to express all the unique functions devices may have. So a driver can define an ioctl which allows a userspace application to send it orders. However, ioctls are not very flexible and tend to get a bit cluttered (dozens of "magic numbers" which just work... or not), and can also be insecure, as you pass a buffer into the kernel - bad handling can break things easily.

另一个选择是sysfs界面，在该界面中您可以在/sys/下设置文件并对其进行读/写操作，以获取驱动程序中的信息.如何进行设置的示例:

An alternative is the sysfs interface, where you set up a file under /sys/ and read/write that to get information from and to the driver. An example of how to set this up:

static ssize_t mydrvr_version_show(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    return sprintf(buf, "%s\n", DRIVER_RELEASE);
}

static DEVICE_ATTR(version, S_IRUGO, mydrvr_version_show, NULL);

在驱动程序安装过程中:

And during driver setup:

device_create_file(dev, &dev_attr_version);

然后，您将在/sys/中拥有一个用于设备的文件，例如，用于块驱动程序的/sys/block/myblk/version.

You would then have a file for your device in /sys/, for example, /sys/block/myblk/version for a block driver.

另一种更常用的方法是netlink，它是一种IPC(进程间通信)方法，用于通过BSD套接字接口与驱动程序进行通信.例如，这由WiFi驱动程序使用.然后，您可以使用libnl或libnl3库从用户空间与其进行通信.

Another method for heavier use is netlink, which is an IPC (inter-process communication) method to talk to your driver over a BSD socket interface. This is used, for example, by the WiFi drivers. You then communicate with it from userspace using the libnl or libnl3 libraries.

这篇关于IOCTL Linux设备驱动程序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！