Kernel upgrade mini-HOWTO

Why upgrade the kernel?

There are mainly two reasons why people wants to upgrade their kernels:

As you are reading this page, you have probably been recommended by Debian-Edu/Skolelinux to upgrade your kernel due to security reasons. In the rest of this document, we assume that you are using Debian-Edu/Skolelinux, and wants to upgrade your kernel due to a security threat and use a new kernel package located in our package repositories.

Preparations

First of all, you have to make sure that your computer has the following line (or similar) present in the /etc/apt/sources.list-file (make sure there's no "#" in the beginning of the line):

deb http://ftp.debian.org/debian/ sarge main

Now you have to find which flavor of the kernel you are running. Do this with the command uname -r (examples: 386, 586tsc, 686, 686-smp, k6, k7, k7-smp).

We assume that you know the name of the kernel-image that you are going to install/upgrade to (example: linux-image-2.6.18-6-<flavor>). Later in this document, this will be referred to as linux-image-<version>-<flavor>. If you have read a Debian-Edu/Skolelinux Advisory, you can probably read there which kernel-image to install.

NB! After upgrading the kernel as described below, you need to reboot the machine for the upgrade to take effect!

NB2! Do not forget to tell your users, (you can check which users that are logged in 'w'-command on the thin-client-server) cause they will loose their work when you reboot. One way of dealing with this, is to enter single user mode on every server, starting with the thin client server (LTSP-servers), by pressing "Alt+Ctrl+F1" logging in as root, with root password, and enter init 1 on the command line. Then follow the procedure below on the Main server first (tjener), and reboot. When tjener comes up after the reboot, do the upgrade on the LTSP-servers.

NB3! The upgrade process may fail if you do not have enough space on your /-partition (check this with 'df -h'). You need about 30-40MB available. If you do not have enough space, you can remove an old kernel-image. To list the kernel-images that are installed, use the command dpkg -l | grep linux-image.

How to upgrade?

Go through these steps to upgrade your kernel:

  1. As root, run apt-get update to update your package lists.
  2. As root, run apt-get install linux-image-<version>-<flavor>.
  3. Reboot the computer (init 0)

To verify that the kernel-upgrade was successfully, run the command uname -a and you should get this output, but with your kernel-version and flavor (this test was from 2.6.18-6 kernel and with a 686-flavor):

Linux sue 2.6.18-6-686 #1 SMP Sun Dec 10 19:37:06 UTC 2006 i686 GNU/Linux

Morten Werner Forsbring
$Id: kernel-upgrade.html.en 59410 2008-02-11 21:48:24Z werner $
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