The Linux Boot Process (Simplified)

The difference between bare metal & virtual machine boot processes

Joe Cardillo
4 min readOct 26, 2021

The Linux boot process differs depending on whether you’re booting directly from hardware (bare metal), or booting a virtualized machine.

Bare metal

This is a term used to indicate you have direct hardware access. In other words, your machine is not running in a virtualized environment.

The boot process on bare metal starts with BIOS.


BIOS stands for “Basic Input/Output System”. It is a very small piece of code contained on a chip on a computer’s motherboard (or system board).

When you start your computer, BIOS is the first software that runs.

Its function is to identify your computer’s hardware, configure, test, and connect it to the OS for further instruction.

To proceed with the boot process, BIOS then checks for a Master Boot Record (MBR).

Master boot record (MBR)

The MBR is (usually) the first 512 bytes of the first sector of a disk. It contains a partition table (which explains how the hard disk is to be partitioned) and the boot loader.