Detailed explanation of Linux kernel functions: a comprehensive interpretation of the five major parts

Detailed explanation of Linux kernel functions: a comprehensive interpretation of the five major parts

The Linux kernel is an open source operating system kernel that is responsible for managing the computer’s hardware resources and providing process management, File system and device driver functions. The Linux kernel is made up of many different parts, each with specific functions and responsibilities. This article will provide a comprehensive explanation of the five major parts of the Linux kernel and provide specific code examples to help readers better understand.

1. Process management

Process management is one of the core functions of the Linux kernel and is responsible for managing all processes running in the system. The Linux kernel uses process descriptors (task_struct) to represent information about each process, including process status, identifier, priority, scheduling information, etc. The following is a simple example code to create a process:

#include <stdio.h>
#include <unistd.h>

int main() {
    pid_t pid;

    pid = fork();

    if (pid == 0) {
        printf("This is a child process
");
    } else if (pid > 0) {
        printf("This is the parent process
");
    } else {
        perror("Process creation failed");
    }

    return 0;
}

2. Memory management

Memory management is another important part of the Linux kernel, responsible for managing the system’s memory resources. The Linux kernel uses page tables to map virtual memory to physical memory and perform memory allocation and release operations. The following is a simple dynamic memory allocation example code:

#include <stdio.h>
#include <stdlib.h>

int main() {
    int *ptr;

    ptr = (int *)malloc(sizeof(int));

    if (ptr == NULL) {
        perror("Memory allocation failed");
        return 1;
    }

    *ptr = 10;
    printf("The value in the allocated memory is: %d
", *ptr);

    free(ptr);

    return 0;
}

3. File system

File system management is another key part of the Linux kernel, responsible for managing files and directories and providing access to and operations on them. The Linux kernel supports multiple file system types, including ext4, NTFS, FAT, etc. The following is a simple sample code for reading and writing files:

#include <stdio.h>
#include <fcntl.h>

int main() {
    int fd;
    char buf[20] = "Hello, Linux!";

    fd = open("test.txt", O_CREAT | O_RDWR, 0644);
    if (fd < 0) {
        perror("File opening failed");
        return 1;
    }

    write(fd, buf, sizeof(buf));
    close(fd);

    return 0;
}

4. Device driver

The device driver is another important part of the Linux kernel and is responsible for managing the hardware devices in the system. The Linux kernel communicates with hardware devices through device drivers and provides access and control of the devices. The following is a simple character device driver sample code:

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>

static int __init mymodule_init(void) {
    printk("Initialize device driver
");
    return 0;
}

static void __exit mymodule_exit(void) {
    printk("Uninstall device driver
");
}

module_init(mymodule_init);
module_exit(mymodule_exit);

MODULE_LICENSE("GPL");

5. Network subsystem

The network subsystem is an important part of the Linux kernel and is responsible for managing network communication and data transmission. The Linux kernel provides functions such as network protocol stacks and socket interfaces to support various network communication protocols and applications. The following is a simple network communication sample code:

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main() {
    int sockfd;
    struct sockaddr_in server_addr;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        perror("Socket creation failed");
        return 1;
    }

    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    server_addr.sin_port = htons(8080);

    if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("Connection failed");
        close(sockfd);
        return 1;
    }

    printf("The connection is successful and network communication is possible
");

    close(sockfd);

    return 0;
}

Summary:

The above is a detailed interpretation of the five major parts of the Linux kernel, including process management, memory management, file system, device driver and network subsystem. Each part plays an important role and together constitute a complete operating system kernel. By in-depth understanding of the working principles and code examples of these parts, readers can better understand the internal structure and operating mechanism of the Linux kernel. Hope this article is helpful to everyone!

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