【My Study Note】The Boot Process
The Boot Process
1. Computer is on
First, the computer is powered on.
2. BIOS/UEFI
The BIOS/UEFI is low-level software that initializes our computer’s hardware to make sure everything is good to go.
So next, the BIOS/UEFI runs a process called the POST (Power On Self Test). The POST performs a series of diagnostic tests to ensure that the computer is properly working.
3. Boot Device will be selected
Depending on the BIOS/UEFI configuration, a boot device will be selected. Devices that are attached to our system, like hard drives, USB drives, CD drives, etc are configured in a specific boot order.
4. Find Bootloader
The devices will be checked in this order and the computer will search for what’s known as a bootloader. The bootloader is a small program that loads the operating system.
5. Bootloader
Once our computer finds a bootloader on a device in the listed order, it will start to execute the program. It will then start to load a larger and more complex program and eventually loads our operating system.
6. Karnel gets loaded
Once the bootloader loads up our operating system, our kernel gets loaded. The kernel controls access to the resources of our computer. It also loads up drivers and more, so our hardware can talk to our software.
7. System processes and User space
Next, essential system processes and user space items are launched. These include processes like user log-in, spinning up a desktop environment, and more which basically allows us to interact with our system.