how to compile linux modules?

[mabuti]

Hello!

Firstly, what is a kernel tree? After reading this documentation, howto (http://tldp.org/LDP/lkmpg/2.6/html/index.html) , and buying a book on how to write linux device drivers. I still cannot compile a simple "hello world" module. My C is very good and I have been using linux for over a year now.
On this (http://tldp.org/LDP/lkmpg/2.6/html/x181.html) documentation, they refer to this folder linux/Documentation/kbuild/ for detailed steps on howto compile modules. However, I could not find it on my Ubuntu . ](*,)

Please help me find my way around, ...can't wait 2 get my hands on the code.
bye

[Juergen]

The 'kernel-tree' is the complete source-code for the kernel and the 'tree' of (sub)directories it lives in.

You probably haven't installed the package 'linux-source-2.6.10' or just 'linux-tree'
It should normally go to /usr/src

And what good is a device-driver that outputs 'hello world'? (where? when?)
Ah, I see, it's an example ;-)

[kamstrup]

You can get the kernel tree from the Ubuntu repositories, but I find this a pain to work with. I'd recommend going to www.kernel.org and grabbing the latest stable release (2.6.12.3 at time of writing). Be aware that you need the FULL sources not the patch. You get these by clicking on the F link to the right of the release title.

NOTE: The danger of using the Ubuntu packages is also that it installs in /usr/src - a place where you need root priviledges to work. Furthermore, unless you change the EXTRAVERSION in the top lines of the Makefile, you can get yourself into BIG trouble. Therefore I again recommend the kernel.org sources , and unpacking them somewhere in you home directory.

With the kernel tree somewhere in you home dir, I'd do something like the following. Compile them as ordinary user: "make menuconfig" to configure stuff... then "make" and finally do "sudo make modules_install". Then copy arch/i386/boot/bzImage and System.map to /boot (as root again - and maybe with sensible names such as vmlinuz-2.6.13.2 and System.map-2.6.13.2).

EDIT: Then add a new entry to /boot/grub/menu.lst, and reboot into your new kernel.

[mabuti]

Alright thanks, I got it. I simply needed to run this command first: sudo apt-get install build-essential linux-headers-`uname -r`.
cheers \\:D/

[kamstrup]

Ok, to make sure that your hacking does not bork up the working kernel+modules, edit /usr/src/linux/Makefile and set EXTRAVERSION = -myversion - substituting something in for myversion.

Or else you modules will be installed on top of the original modules causing a mess...