LPI Linux Certification/Install A Boot Manager

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Detailed Objective[edit]

Weight: 2

Description:
Candidates should be able to select, install and configure a boot manager.

  • Key knowledge area(s):
    • Providing alternative boot locations and backup boot options
    • Install and configure a boot loader such as GRUB.
    • Interact with the boot loader.
  • The following is a partial list of the used files, terms and utilities:
    • /boot/grub/menu.lst
    • grub-install
    • MBR
    • superblock
    • /etc/lilo.conf
    • lilo


Boot managers[edit]

A boot loader is installed in the MBR (Master Boot Record). When a system starts, it loads what is in the MBR to RAM. Under Linux there are two main boot loaders:

  • Lilo: LInux LOader.
  • Grub: GRand Unified Boot Loader.

A boot loader allows you to select the image that you would like to boot from. A system can contain multiple images (operating systems).

A boot loader allows you to interactively run commands and pass parameters to the image that you will boot. The initrd is the driver that will be used to build a filesystem on RAM to mount other filesystems and execute programs.

GRUB is today's default boot loader for many distributions. When installing Windows with Linux, install Windows first and Linux second, because Windows overwrites the MBR without asking.

LILO vs. GRUB[edit]

Both are used to load an image from a disk to RAM. GRUB has the following advantages to LILO:

  • More pre-OS commands.
  • Supports images stored beyond the 1024 BIOS cylinder limitation.
  • Can access its configuration file through the filesystem.

When using LILO, each time you add a new image or change an image a new LILO needs to be installed in the MBR.

  • LILO keeps its boot information in the MBR
  • GRUB keeps its boot information in the filesystem (menu.lst).
  • LILO also has a configuration file /etc/lilo.conf.

To install GRUB on the MBR, use grub-install. The command setup will override the MBR.

To install LILO on the MBR, use lilo. The lilo will use the /etc/lilo.conf file to know what to write into the MBR.

Example of /etc/lilo.conf:

# LILO global section
boot = /dev/hda # LILO installation target: MBR
vga = normal # (normal, extended, or ask)
read-only # Mount the root file systems read-only

# LILO Linux section
image=/boot/vmlinuz # Image to load
label=linux   # Label to display
root=/dev/hda1  # Root partition for the kernel
initrd=/boot/initrd # Ramdisk

# LILO DOS/Windows section
other=/dev/hda3
label=windows
# LILO memtest section
image=/boot/memtest.bin
label=memtest86

Example of menu.lst (GRUB configuration file):

# GRUB default values
timeout 10 # Boot the default kernel after 10 seconds
default 0 # Default kernel

# Grub for Linux section 0
title GNU/Linux  # Title
root (hd0,1)  # /dev/hda2 root filesystem
# Kernel and parameters to pass to the kernel
kernel /boot/vmlinuz root=/dev/hda2 read-only
initrd /boot/initrd
boot

# Grub for DOS/Windows section
title Winblows
root (hd0,2)  # /dev/hda3
makeactive
chainloader+1

GRUB Resources[edit]

 * GRUB Manual
 * GRUB homepage
 * Grub wiki
 * Linux+Win+Grub HowTo
 * Linux Recovery and Boot Disk Creation with Grub.
 * Win32 Grub
 * Booting with GRUB
 * WinGRUB
 * GRUB Installer for Windows
 * GRUB for DOS - Bridging DOS/Windows to Unix/Linux

Exercises[edit]

1) Install Grub on a floppy disk and try to boot your image manually:

mkfs -t ext2 /dev/fd0
mount /dev/fd0 /mnt
mkdir -p /mnt/boot/grub
cp /boot/grub/stage* /mnt/boot/grub/
cp /boot/grub/e2fs-stage1_5 /mnt/boot/grub/
touch /mnt/boot/grub
umount /mnt
grub
root (fd0)
setup (fd0)
quit

Now reboot with the floppy and from the prompt select the kernel on the hard disk.

root (hd0,1)
kernel /boot/vmlinuz root=/dev/hda2 read-only
initrd /boot/initrd
boot

2) Create /boot/grub/menu.lst file and install Grub on your hard drive with the grub utility.

3) Install back lilo. Change the linux label of the default kernel image to SuSE in /etc/lilo.conf and re-install the lilo program in the MBR.