Bootstrapping Boot Process - aryanjoshi0823/5143-Operating-System GitHub Wiki

What is the Boot Process?

The boot process refers to the series of events that occur from powering on a computer to the point where the operating system is ready for use. It initializes hardware, loads the operating system, and starts essential services.

The boot process is vital because, at startup, the computer's memory (RAM) is empty, and the operating system must be loaded into it to manage resources and execute programs.

Steps in the Boot Process

  1. Power-On Self-Test (POST):

    • After powering on, the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface) runs the POST.
    • POST checks hardware components (CPU, memory, storage devices) to ensure functionality.
    • Errors during POST halt the boot process, showing error codes or beeps.

  2. Loading the Bootloader:

    • BIOS/UEFI identifies a bootloader on the primary boot device (e.g., hard drive, SSD, or USB).
    • The bootloader is a small program responsible for loading the operating system's kernel.

  3. Executing the Bootloader:

    • The bootloader (e.g., GRUB, BOOTMGR) runs and provides options for selecting the operating system if multiple are installed.
    • It loads the kernel into memory.

  4. Loading the Kernel:

    • The bootloader hands control to the operating system's kernel.
    • The kernel initializes system resources like device drivers and memory management.

  5. Initializing System Components:

    • The kernel sets up core systems, including process scheduling, memory management, and filesystem mounting.

  6. Starting System Services:

    • Essential services, such as networking and authentication, are launched.

  7. Launching the User Interface:

    • The graphical or command-line interface (GUI or CLI) is started, allowing user interaction.
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