Linux Bootloader Process

Step-by-step guide for Red Hat and Ubuntu

Step 1: BIOS/UEFI Initialization

The system starts with BIOS or UEFI firmware initializing hardware components and locating the bootloader.

BIOS/UEFI Initialization

Step 2: MBR Partitions Selection

The BIOS/UEFI reads the Master Boot Record (MBR) or GUID Partition Table (GPT) to find the bootloader location.

MBR Partitions Selection

Step 3: Bootloader Execution

The bootloader (GRUB for Red Hat and Ubuntu) is loaded into memory and executed.

Bootloader Execution

Step 4: Kernel Loading

The bootloader loads the Linux kernel and initial RAM disk (initrd) into memory.

Kernel Loading

Step 5: Init System

The init system (systemd for modern Red Hat and Ubuntu) takes over and starts essential services.

Init System

Step 6: Systemd Service

Systemd is the default init system for modern Linux distributions, managing services and dependencies.

Systemd

Step 7: User Login

The system reaches the login prompt or graphical interface, ready for user interaction.

User Login