Linux MBR: Basic functions of bootloader

Linux MBR: The basic role of the startup boot program, specific code examples are required

During the startup process of the computer, the Master Boot Record (MBR, Master Boot Record) plays the role of plays a vital role. The MBR is a small program stored in the first sector of the hard disk that contains information such as the boot loader and partition table. When the computer starts, the BIOS will first load the MBR and then execute the boot loader in it to boot the loading of the operating system.

The basic function of MBR:

1. Boot loader: MBR contains the boot loader, which is responsible for loading the kernel of the operating system. In Linux systems, the boot loader is usually GRUB (GRand Unified Bootloader).
2. Partition table information: MBR also contains the partition table information of the hard disk, which records the partition layout of the hard disk and helps the boot loader find the partition where the operating system is located.
3. Start the operating system: Through the boot loader, MBR can correctly start the operating system and provide users with a computer usage environment.

Let’s take a look at a simple Linux MBR code example:

Code example:

section .text
    global _start

_start:
    jmp main

print_string:
    mov ah, 0x0E
    mov bh, 0x00
    xor bl, bl

print_loop:
    lodsb
    test al, al
    jz print_done

    int 0x10
    jmp print_loop

print_done:
    ret

main:
    mov si, hello_message
    call print_string

    jmp $

hello_message db "Welcome to Linux MBR!", 0x0D, 0x0A, 0

times 510-($-$$) db 0
dw 0xAA55

The above is a simple assembly code example for A welcome message displays when the computer starts. This example implements the function of loading code from the MBR to printing a welcome message on the screen.

Summary:

Linux’s MBR plays an indispensable role in the computer startup process and is responsible for booting the loading of the operating system. Through the above code examples, we can have a preliminary understanding of the basic functions and implementation methods of MBR. In-depth study and understanding of the principles of MBR will help us better understand the computer startup process and operating system loading process.

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