In-depth analysis of kernel initialization in the Linux system startup process

Kernel initialization phase: Detailed introduction to the Linux system startup process

In the Linux operating system, kernel initialization is an important stage of system startup. It is responsible for performing various initialization operations and preparing the environment in which the system will run. This article will introduce the Linux system startup process in detail, including kernel loading, startup, initialization, etc., and provide some specific code examples to help readers better understand.

1. Kernel loading phase

When the computer is turned on, the BIOS will first load the bootloader, such as GRUB or LILO. The bootloader is responsible for finding it on the hard disk or network. kernel image and load it into memory. Once the kernel is loaded, control is given to the kernel.

Code example:

section .text
    global _start

_start:
    ; 这里可以编写加载内核映像到内存的汇编代码

2. Kernel startup phase

After the kernel starts, it will perform a series of initialization operations, including setting the interrupt vector table, initialization Page tables, build process scheduler, etc. Through these initialization operations, the kernel prepares the basic operating environment required by the system.

Code example:

void setup_arch()
{
    // 设置中断向量表
    set_idt();
    
    // 初始化页表
    init_pagetables();
    
    // 构建进程调度器
    setup_scheduler();
}

3. Kernel initialization phase

In the kernel initialization phase, more detailed initialization operations will be performed, including initializing various device drivers. , mount the root file system, establish a user-mode environment, etc. These operations bring the system to a runnable and operational state.

Code example:

void start_kernel()
{
    // 初始化设备驱动
    init_devices();
    
    // 挂载根文件系统
    mount_rootfs();
    
    // 建立用户态环境
    setup_userspace();
}

4. Start user space

After the kernel initialization is completed, user space initialization operations will be performed, such as starting the init process to load User-level program completes the system startup process.

Code example:

int init()
{
    // 启动init进程
    start_init_process();
    
    // 加载其他用户级程序
    load_user_programs();
    
    return 0;
}

Summary: The startup process of a Linux system includes multiple stages such as kernel loading, startup, initialization, and user space startup. Each stage is crucial. Through the introduction and code examples of this article, I believe readers can better understand the startup process of the Linux system and benefit from system debugging and development.

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