Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions

  




 

 

Modifying the Bootloader For the New Kernel

There are two common Linux kernel bootloaders: GRUB and LILO. GRUB is the one more commonly used in modern distributions, and does some things a little more easily than LILO, but LILO is still seen as well. We'll cover both in this section.

To determine which bootloader your system uses, look in the /boot/ directory. If there is a grub subdirectory:

$ 
ls -F /boot | grep grub

grub/

then you are using the GRUB program to boot with. If this directory is not present, look for the presence of the /etc/lilo.conf file:

$ 
ls /etc/lilo.conf

/etc/lilo.conf

If this is present, you are using the LILO program to boot with.

The steps involved in adding a new kernel to each of these programs are different, so follow only the section that corrisponds to the program you are using.

GRUB

To let GRUB know that a new kernel is present, all you need to do is modify the /boot/grub/menu.lst file. For full details on the structure of this file, and all of the different options available, please see the GRUB info pages:

$ 
info grub

The easiest way to add a new kernel entry to the /boot/grub/menu.lst file is to copy an existing entry. For example, consider the following menu.lst file from a Gentoo system:

timeout 300
default 0

splashimage=(hd0,0)/grub/splash.xpm.gz

title 2.6.16.11
	root (hd0,0)
	kernel /bzImage-2.6.16.11 root=/dev/sda2 vga=0x0305

title 2.6.16
	root (hd0,0)
	kernel /bzImage-2.6.16 root=/dev/sda2 vga=0x0305

The line starting with the word title defines a new kernel entry, so this file contains two entries. Simply copy the lines from one instance of the title word to the next one, such as :

title 2.6.16.11
	root (hd0,0)
	kernel /bzImage-2.6.16.11 root=/dev/sda2 vga=0x0305

to the end of the file, and edit the version number to contain the version number of the new kernel you just installed. The title does not matter, so long as it is unique, but it is displayed in the boot menu, so you should make it something meaningful. In our example, we installed the 2.6.17.11 kernel, so the final copy of the file looks like:

timeout 300
default 0

splashimage=(hd0,0)/grub/splash.xpm.gz

title 2.6.16.11
	root (hd0,0)
	kernel /bzImage-2.6.16.11 root=/dev/sda2 vga=0x0305

title 2.6.16
	root (hd0,0)
	kernel /bzImage-2.6.16 root=/dev/sda2 vga=0x0305

title 2.6.17.11
	root (hd0,0)
	kernel /bzImage-2.6.17.11 root=/dev/sda2 vga=0x0305

After you save the file, reboot the system and ensure that the new kernel image's title comes up in the boot menu. Use the down arrow to highlight the new kernel version, and press Enter to boot the new kernel image.

LILO

To let LILO know that a new kernel is present, you must modify the /etc/lilo.conf configuration file and then run the lilo command to apply the changes made to the configuration file. For full details on the structure of the LILO configuration file, please see the LILO man page:

$ 
man lilo

The easiest way to add a new kernel entry to the /etc/lilo.conf file is to copy an existing entry. For example, consider the following LILO configuration file from a Gentoo system:

boot=/dev/hda
prompt
timeout=50
default=2.6.12

image=/boot/bzImage-2.6.15
	label=2.6.15
	read-only
	root=/dev/hda2

image=/boot/bzImage-2.6.12
	label=2.6.12
	read-only
	root=/dev/hda2

The line starting with the word image= defines a new kernel entry, so this file contains two entries. Simply copy the lines from one instance of the image= word to the next one, such as:

image=/boot/bzImage-2.6.15
	label=2.6.15
	read-only
	root=/dev/hda2

to the end of the file, and edit the version number to contain the version number of the new kernel you just installed. The label does not matter, so long as it is unique, but it is displayed in the boot menu, so you should make it something meaningful. In our example, we installed the 2.6.17.11 kernel, so the final copy of the file looks like:

boot=/dev/hda
prompt
timeout=50
default=2.6.12

image=/boot/bzImage-2.6.15
	label=2.6.15
	read-only
	root=/dev/hda2

image=/boot/bzImage-2.6.12
	label=2.6.12
	read-only
	root=/dev/hda2

image=/boot/bzImage-2.6.17
	label=2.6.17
	read-only
	root=/dev/hda2

After you save the file, run the /sbin/lilo program to write the configuration changes out to the boot section of the disk:

# /sbin/lilo

Now the system can be safely rebooted. The new kernel choice can be seen in the list of kernels that are available at boot time. Use the down arrow to highlight the new kernel version, and press Enter to boot the new kernel image.


 
 
  Published under the terms of the Creative Commons License Design by Interspire