what is linux kernel

linux kernel means linux kernel, which mainly functions to complete IO driver device management, TCP/IP and task scheduling; linux kernel is the main component of the Linux operating system and the core interface between computer hardware and its processes. , which is responsible for the communication between the two and also manages the resources as efficiently as possible.

#The operating environment of this tutorial: linux5.9.8 system, Dell G3 computer.

What is linux kernel?

linux kernel means linux kernel, which mainly functions to complete IO driver device management, TCP/IP, and task scheduling.

Linux kernel is translated as linux kernel, which is based on the linux platform. Linux is a kernel written in C language. Based on this kernel, specific operating systems such as Red hat linux and open suse linux are derived. A complete operating system based on the Linux kernel is called the Linux operating system, or GNU/Linux.

Linux Kernel Introduction

The Linux kernel is the main component of the Linux operating system (OS) and the core interface between computer hardware and its processes. It is responsible for the communication between the two and also manages the resources as efficiently as possible.

It’s called the kernel because like the seed in the hard shell of a fruit, within the operating system, it controls everything about the hardware (whether it’s a phone, laptop, server, or any other type of computer). The main function.

The role of the Linux kernel

The content has the following four functions:

• Memory management: Track how much memory is stored What is stored and where

• Process management: Determine which processes can use the central processing unit (CPU), when and for how long

• Device driver: Acts as a mediator/interpreter between the hardware and the process

• System call and security protection: Accepts service requests from the process

When implemented correctly, the kernel is invisible to the user and works in its own little world (called kernel space) from which it allocates memory and keeps track of where everything is stored. What the user sees (such as the web browser and files) is called user space. These applications interact with the kernel through the system call interface (SCI).

It can be understood this way: the kernel is like a busy personal assistant serving executives (hardware). The assistant's job is to forward messages and requests (processes) from employees and the public (users) to executives, remember what is stored and where (memory), and determine who can visit with the executive at any given time and when meetings are available. how long.

For the Linux kernel, let’s first look at its directory structure. Here are just a few important instructions.

arch includes all core code related to the architecture. From inside we can see folders such as arm, alpha, i386, mips, and ia64. Each processor architecture has different hardware modules. Here we need to perform different initializations for different architectures.

init contains the kernel initialization code (not the system boot code), which has a main.c file, which is used to perform all initialization work of the kernel (including initializing memory, initializing all hardware, and creating the first task task0, set the interrupt enable flag), then move to user mode and call the fork() function to create a new process and run the shell on the console.

kernel contains the core code of kernel management. Just look at the name and you will know that this is a heavyweight directory. It contains all the programs that handle tasks, including fork, exit, scheduler (sched.c) and some system calls. (sys.c), signal processing (signal.c), time function (time.c), as well as a series of functions with intricate calling relationships, such as interrupt exception handling, power management, etc.

mm contains all memory management code. These include realizing the mapping of the logical address of the process to the actual physical address, implementing the paging and segmentation mechanism, and implementing the memory page exception interrupt handler, etc.

drivers include all device drivers in the system, such as cdrom, bluetooth, pci, i2c, etc.

ipc contains the core inter-process communication code.

fs stores the file system code supported by Linux, which contains a bunch of directories such as ext2, ext3, ext4, fat, ntfs, etc.

net is the network part code of the kernel, and each of its subdirectories corresponds to an aspect of the network, such as ieee80211, ipv4, and ipv6 directories.

lib contains the core library code, including functions such as strcpy, sprintf, and sort.

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