In our last post we covered the basics of Linux System Initialization. Now let's take a deeper look at the Linux Boot Loader.

There are two possible ways to configure boot loaders:

  • Primary Boot Loader: Install the first stage of the boot loader into the MBR, but the boot loader must be configured to pass control to any other desired OS.
  • Secondary Boot Loader: Install the first stage into the boot sector of any partition on disk. Another boot loader must be installed and configured in the MBR to pass control to the OS.

There are two basic boot loaders used in Linux distributions:

  1. GRUB -- Grand Unified Boot Loader
  2. LILO -- Linux Loader (obsoleted)

In this article we'll focus on GRUB.

Working of GRUB Link to heading

  • Select an Operating System from the HDD
  • Identify the partition with the help of appropriate boot files
  • Locate the kernel on the HDD
  • Run initial ram disk to set up the kernel and associated modules

Benefits of GRUB Link to heading

  • Provides password-based security at system startup
  • Easy to edit during the boot process without making persistent changes
  • Allows booting from Windows XP/Vista/7 from the MBR
  • Supports LBA (Logical Block Addressing) mode, which helps the system find boot files beyond the 1024th cylinder on the HDD

GRUB Configuration Link to heading

Configuration of GRUB is simple but varies according to the Linux distribution.

Originally published August 29, 2011 on jaymspatel.blogspot.com