boot process

The Boot Process

BIOS

​​​​​​(Basic Input/Output System)

Starting an 86-based Linux system

The BIOS initializes the hardware

Screen

Keyboard

Test the main memory

Is stored on a ROM chip in the mother board

The process is also called POST (Power On Self Test)

The remainder of the boot process is cntroled by the OS

Including

Master Boot Record

(MBR)

The system control passes from de BIOS to the boot loader

Is usually stored on one of the first sector of the hard disks

Boot sector

EFI partition

BIOS

MBR

UEFI

or

Up to this part, does not access any mass storage media

From the CMOS is loaded

Thereafter

Date

Time

The most important peripherals

most common ones

GRUB, ISOLINUX, DAS U-Boot

Responsible for loading

Kernel

The initial RAM disk

Filesystem

Boot Loader

Executes

The size of the MBR is just 512 bytes

Either

In this stage, the boot loader examines the partition table and finds a bootable partition.

Then: searches for the second stage boot loafder

Executes

KERNEL

Initial RAM Disk

The boot loader loads the selected kernel image and passes control to it. Kernels are almost always compressed, so its first job is to uncompress itself.After this, it will check and analyze the system hardware and initialize any hardware device drivers built into the kernel.

boot loader resides under /boot

initramfs

Programs

Binary files

perform all actions needed to mount the proper root filesystem

Mount proper root filesystem

Providing kernel functionality

Locating devices

Locating drivers and load them

Checking for errors in root filesystem

Contains