There are several categories of equipment in the Linux system

Devices in the Linux system are divided into three categories: 1. Character devices are devices that can be accessed like a byte stream. When a read or write request is issued to a character device, the corresponding IO operation occurs immediately; 2. Block devices are devices that must be accessed in blocks when performing TO operations in Linux systems. Block devices can install file systems; 3. Network devices are driven by the Linux network subsystem and are responsible for sending and receiving data packets. It is not oriented to stream devices, so there are no nodes for network devices in the Linux system file system.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

Devices in the Linux system

Devices in the Linux system can be divided into three categories: character devices, block devices and network devices.

(1) Character device

A character device is a device that can be accessed like a byte stream. When a read or write request is issued to a character device, the corresponding IO operation Happens immediately. Many devices in the Linux system are character devices, such as character terminals, serial ports, keyboards, mice, etc. In embedded Linux development, the most common ones are character devices and drivers.

(2) Block device

Block device is a device that must be accessed in blocks when performing TO operations in the Linux system. Block devices can install file systems. The block device driver will use a piece of system memory as a buffer, so issuing read and write accesses to the block device does not necessarily result in hardware I/O operations immediately. Common block devices in Linux systems include hard disks, floppy drives, etc.

(3) Network equipment

Network equipment can be either a hardware device such as a network card, or a pure software device such as a loopback device. Network devices are driven by the Linux network subsystem and are responsible for sending and receiving data packets, rather than stream devices. Therefore, network devices do not have nodes in the Linux system file system. Access to network devices is generated through socket calls, rather than ordinary file operations such as open/closc and read/write.

The status of driver in Linux

The driver is the bridge between the device and the user in the Linux system. In the Linux system, accessing the device must Operating through the device driver, the user program cannot directly operate the device. The relationship between hardware, drivers and user programs in the Linux system is shown in Figure 2.2.

The driver runs in the kernel space. User programs can only access and operate the hardware and data transferred by the hardware device through the system calls provided by the kernel, VFS and the driver. It must also go through the driver, VFS and system calls before it can be received by the user program. Therefore, device drivers are bridges and channels for applications to access system devices and transfer data.

Related recommendations: "Linux Video Tutorial"

The above is the detailed content of There are several categories of equipment in the Linux system. For more information, please follow other related articles on the PHP Chinese website!