What is a kernel module in linux

In Linux, the kernel module is a socket provided by the Linux kernel to the outside world; the kernel module is a program with independent functions that can be compiled separately, but cannot run independently. It is a program that is used by the kernel or other kernel modules. Functional code block.

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

What is a kernel module in Linux

The kernel module is a socket provided by the Linux kernel to the outside world. Its full name is dynamically loadable kernel module (Loadable Kernel Module, LKM). We call it module for short. . The reason why the Linux kernel provides a module mechanism is that it is a monolithic kernel. The biggest advantage of a single core is high efficiency because everything is integrated together, but its disadvantage is that its scalability and maintainability are relatively poor. The module mechanism is to make up for this shortcoming.

A module is a program with independent functions. It can be compiled separately, but cannot run independently. It is linked to the kernel at runtime and runs in kernel space as part of the kernel, which is different from processes running in user space. A module usually consists of a set of functions and data structures that implement a file system, a driver, or other upper-level kernel functionality.

In short, a module is a block of code that provides functionality for the kernel (in a sense, the kernel is also a module) or other kernel modules.

The kernel module of a Linux system is a block of code that can be loaded into or unloaded from the kernel as needed, so the functionality of the kernel can be extended without restarting. But unless the user uses a command like lsmod to query module information, the user is unlikely to know about any changes to the kernel.

There are many modules available on Linux systems, and you can learn a lot of details if you delve into them. One of the main uses of the Linux system tool lsmod is to check modules when the system is not working properly.

1. Display the kernel module

The easiest way to display the kernel module is to use the lsmod command. Although this command contains a lot of details, the output is very user-friendly, generally in the output:

1) Module displays the name of each module

2) Size displays the size of each module Size, not the memory size they occupy

3) Used by displays the number of times each module is used and the modules that use them

The number of loaded modules depends on the system and version used and To view the running content, you need to check the number of modules available in the system, not just those that are running. You can use this operation command:

1) $ modprobe -c | wc –l

2) 41272

2. Other commands related to kernel modules

The Linux system provides several commands for listing, loading and unloading, testing, and checking module status.

1) depmod - Generate modules.dep and mapping files

2) insmod - A program that inserts modules into the Linux kernel

3) lsmod - Display Linux Module status in the kernel

4) modinfo - Display Linux kernel module information

5) modprobe - Add or remove Linux kernel module

6)rmmod - A Program to remove modules from the Linux kernel

3. Display built-in kernel modules

As the editor mentioned earlier, the lsmod command is the most convenient command to display kernel modules. . However, there are other ways to display them. All modules built into the kernel are listed in the modules.builtin file, which is used when the modprobe command attempts to add modules in the file.

Users can use modinfo to get more details about a module, although there is no simple description of the services provided by the module, and can also use the modprobe command to load or unload modules. Use the following command to find the kernel object associated with a specific module:

1）$ find /lib/modules/$(uname -r) -name floppy*
2）/lib/modules/5.0.0-13-generic/kernel/drivers/block/floppy.ko

If you want to load a module, you can use this command: $ sudo modprobe floppy.

Obviously, the loading and unloading of kernel modules is very important. It makes Linux systems more flexible and efficient than when running with a general-purpose kernel. This also means users can make major changes without rebooting, such as adding hardware.

Related recommendations: "Linux Video Tutorial"

The above is the detailed content of What is a kernel module in linux. For more information, please follow other related articles on the PHP Chinese website!