Setting Up Ubuntu for Building Kernel Modules

When you build kernel modules or other programs that depend upon the kernel you need to have the kernel source configured per the currently running kernel. To see what kernel your machine is running, simply run uname -a. To setup your machine to allow things to build against the kernel, you first need the source for your currently running kernel:

export KERNEL_VERSION=`uname -r|cut -d '-' -f 1`
sudo aptitude install linux-source-$KERNEL_VERSION
cd /usr/src/
sudo tar jxf linux-source-$KERNEL_VERSION.tar.bz2
sudo ln -s linux-source-$KERNEL_VERSION linux
ln -s /usr/src/linux /lib/modules/`uname -r`/build

First, in order to get things to build against the kernel you have to alter a single file to match the kernel you’re running. Run uname -r and note everything following the first three decimal-separated numbers:

$ uname -r
2.6.17-10-386

Just use a text editor (vi!) and edit /usr/src/linux/Makefile, changing the EXTRAVERSION variable to match yours from above:

VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 17
#EXTRAVERSION = .14-ubuntu1
EXTRAVERSION = -10-386
NAME=Crazed Snow-Weasel

Next, you need to get the .config for the running kernel and setup the kernel source:

sudo cp /boot/config-`uname -r` /usr/src/linux/.config
cd /usr/src/linux
make oldconfig
make prepare0
make scripts

That’s it. Now you should be able to build things, like kernel modules, against the kernel source.