1. Bootloader / multi-boot

2. Bootloaders
Grand Unified Bootloader (GRUB)
Linux Load (LILO)

3. GRUB
Discovers boot images, kernels, and root filesystems from GRUB command shell
Stores boot info in a filesystems (not the MBR)
Reads filesystems and kernel executables
Does not restrict user to disk geometry
OS independent
Store GRUB in a separate boot partition
Remove and reinstall OS’s w/o having to reinstall the bootloader

4. GRUB and LILO Can boot non-Linux systems Chain loading
Windows, OS/2, BSD, etc
Chain loading
Points to OS’s bootloader (ie, Windows)

5. MBR
First 512 bytes of the first sector of the first partition on a drive
Contains partition table and 1st stage bootloader
1st stage is first 445 bytes
Point to 2nd stage loader
Stored in /boot directory
Remaining 66 bytes
Partition table

6. Linux Limited to 63 total partitions per IDE drive SCSI drives
3 primary
4th: contains up to 60 logical partitions in a single extended partition
SCSI drives
Limited to 15 partitions
3 primaries
12 logicals

7. Scenario LILO installed, you wish to install GRUB
Determine the version of grub
$grub –version
grub (GNU GRUB 0.94)
Hard copy your partition table
fdisk –l | lpr
Hard copy lilo.conf
Back up data
Keep rescue disk handy
LILO boot or Knoppix
Leave LILO intact… in case
Create GRUB boot diskette
Install GRUB to MBR
Boot the system
Edit GRUB configuration file
menu.lst

8. Scenario Create GRUB boot diskette
/grub/i386-pc (can vary)
could be in /usr/lib or /usr/share or…
Copy stage1 and stage2 to diskette with dd command
$ dd if=stage1 of=/dev/fd0 bs=512 count=1
Reboot the system (you get the GRUB screen)
Find the root device
grub> find /boot/grub/stage1
(hd0,0)
Set the root device
grub> root (hd0,0)
Install GRUB to MBR
grub> setup (hd0)
Set the root device (again)
Enter the path to the kernel and the root filesystem (in lilo.conf)
MAKE SURE YOU APPEND “ro” (read only)
grub> kernel /boot/vmlinuz root=/dev/hda1 ro
Now, boot the system
grub> boot

9. Gotchas Linux refers to drives as hd1, hd2, etc…
GRUB starts with “0” (h0, h1, etc)
Both SCSI and IDEs are hd, floppies are fd
Linux primary partitions
1-4
5 and up.. Extended partitions
GRUB
0-3 primary
4 and up extended
Identifying the root filesystem does not use GRUB’s numbering sytem
grub> kernel /boot/vmlinuz root=/dev/hda1 ro

10. Install GRUB w/o floppy
Start a grub shell
# grub
Find the stage1 loader
grub> find /boot/grub/stage1
(hd0,0)
Run
grub> root (hd0,0)
grub> setup (hd0)
grub> quit
Reboot

11. Multi-booting Linux Standalone /boot partition
Shared /home and /swap partitions
Standard Fedora install (on 20Gb IDE)
/dev/hda1 primary 100Mb /boot
/dev/hda2 primary 2,500Mb /
/dev/hda3 primary 3,000 Mb /home
/dev/hda4 extended
/dev/hda Mb /swap
Free space 14,144

12. Disk Druid Used to partition Delete any existing partitions
Highlight ‘free space’
Click ‘new’
Mountpoint is /boot ext2, 100Mb
Select ‘free space’ again
‘new’
Mountpoint is “/” ext3, 2500Mb
Next
/home ext3, 3000Mb
Find “swap” no mountpoint, 256Mb
When done, save changes using Disk Druid
Continue install, using GRUB (not LILO)

13. QTPared Create, delete, move and resize partitions /swap /home
Included on Knoppix
Can be used to set up partitions even before new Linux install
Can be used to make changes to partitions even if data on them
/swap
Performance issues, put in its own partition
Shared on multiboot system
/home
Own partition
Share between different Linux systems
Not forced to restore data from backup when installing or removing systems

14. Adding another Linux
Add additional Linux systems into logical partitions
Create a GRUB boot menu entry for each
After 1st Linux installed
Boot install of the new Linux
Partition and drive layouts
Highlight “free” and select “new”
2500Mb for size (mountpoint is “/”)
Select filesystem type and initialize it (/dev/hda6)
Select /dev/hda3 to “Modify”
Select /home and ext3, do not initialize it
When done, write the partition info to disk
When prompted, you should only be formatting or initialing the “/” partition
Do NOT overwrite the MBR
Do you want Linux to handle booting system? “NO”
You want boot files installed to first sector of the root partition (/dev/hda6)
Use GRUB
grub> root (hd0,0)
grub> kernel / boot/vmlinuz-2,4,21 root=/dev/hda6 ro
grub> boot

15. Finding the boot parameters using GRUB
As grub is booting up, hit “c”
Get to the GRUB command shell
grub>root (hd0, <tab> [tab completion]
possible partitions identifies along with filesystem type and partition type
Try them if needed…
grub> root (hd0,0)
Search for kernel image
grub> kernel /boot/vmlinuz<tab>
May report file not found
grub> root (hd0,1)
possible files are: vmlinuz vmlinuz-2.4.2
grub> kernel / boot/vmlinuz-2,4,21 root=/dev/hda2 ro
grub> boot

16. Miscellaneous grub> cat /etc/shadow grub> root(hd<tab>
Possible disks are: hd0 hd1
Grub can be password protected
Documentation

17. GRUB boot menu /boot/grub/menu.lst “stanza” GRUB boot entry
title Fedora 1 core
root (hd0,0)
kernel /boot/vmlinuz root=/dev/hda1 ro
initrd /boot/initrd img
Title: required, can be anything
Each OS requires a stanza entry
Initrd: ramdisk (not all Linux implementations require a ramdisk)

18. GRUB boot menu menu.lst (or grub.conf) Default entry Timeout entry
Number of the stanza (sequential)
Timeout entry
How long to wait for default entry to boot
splashimage
defaultsaved
Last image used to boot is saved as the next default

19. Adding Windows to a Linux system
Different considerations for 95 thru ME as opposed to NT/2000/XP XP
Make sure there’s enough free space and unused primary partition
Hard copy the partition table
Note what’s installed on each partition
Install from CD
Install complete
Restore the GRUB to the MBR
Load GRUB boot floppy
grub> root (hd0,0)
grub> setup (hd0)
grub> reboot
Boot to Linux, and make an entry for the Windows system
title WindowsXP on /dev/hda4
rootnoverify (hd0,3)
makeactive
chainloader +1

20. Restore GRUB to MBR w/Knoppix
If installation of Windows overwrote the MBR and GRUB with the Windows Boot Menu you can no longer boot to Linux
Boot the Knoppix CD
su to root and run GRUB
Put GRUB onto the MBR
grub> Root (hd0,0)
grub> setup (hd0)
grub> quit
Reboot and GRUB menu appears

21. Password protecting GRUB
# grub-md5-crypt
Copy and paste the encrypted password into menu.lst before the boot stanzas
password –md5 $1$riAfJ0$QTuA1S/BGqlkYHQADZejs1
Or… plaintext password can be used…
password mypasswordisthis
Chmod the menu.lst file if needed (root only)
When booting GRUB, hit “p” and enter the password to unlock the command shell
Users can still select.. Just can use command shell
(**** if you forget the GRUB password, anyone can simply boot with rescue disk and edit menu.lst *****)

22. Assignment: Install Red Hat on box w/GRUB
Install Mandriva as second Linux
Install Windows XP as third system