Very nice well written, this nice step by step tutorial is exactly for me.

---
"... Nothing Runs Like A Python ..."

Great tutorial!

I am amazed!! How have you managed to get this thing so simple? A real good job.

Sundip Sharma

Thanks
a great article with ample scope of learning the skeleton of linux device drivers and the commonly used functions in them.........so simple and presented in quite an interesting way, so never lets u feel bored.
great work

After kernel 2.4 the kernel compilation and adding up of modules has changed drastically. This tutorial helped me compile and insert my module. Thanks. Effort whole heartedly appreciated.

Kabeer Ahmed.

A great article with ample scope of learning with
nice step by step procedure..

Thank's
Prakash.

Its a good information.

Regards, Rajesh

Great Work !!!

"Linux's kernel" has no sense, because Linux is a kernel

Hi All,

I actually tried memory.ko as below:

$echo -n abcdef > /dev/memory

$cat /dev/memory
f
But I've got only the last written character i.e., 'f'.

I changed the code so that the buffer can hold upto 10 bytes (by giving 10 as a parameter to kmalloc and read,write calls) but still I'm getting the last input character. Can any one post teh answer here...

--
Regards,
Vishwa

A really good and Helpful link for newbies!!!!

hi,

This one is good article.
I want to learn more on this, and can u help me get more info about device drivers.

Thanks,
Raghavendra

Gud work by u.A gud guide for a layman in the fiels of device drivers

Heartly appreciated

hello sir whhen i have compiled my sorce code then i face an error that "fops size is not known " pleee send me some information to remove this error
mu email id is erabhinandan@gmail.com

Thank you for your excellent tutorial!

That's true that the first step is always the more hard to achieve, and guides like this really simplify the achievement of the basic know-how necessary to get real job done.

When I first tried the tutorial I get this error when trying to insmod my module nothing.ko:
insmod: error inserting nothing.ko: -1 Invalid module format

while dmesg gave me:
nothing: version magic '2.6.17.11.061003.eramil SMP mod_unload PENTIUM4 REGPARM gcc-4.1' should be '2.6.17.11.061003.eramil SMP mod_unload PENTIUM4 REGPARM gcc-4.0'

It was that I like to add a customized extra version to my kernel compiling it, while the extra version in the source tree Makefile was still ".11".
To fix this I changed manually the Makefile, updating the extra version line with the current linux extra version, then I started to compile with make (but I control-C-ed quite soon, after the compilation of the version.h file, that you can eventually change by hand).

Then, since I compiled the kernel with gcc-4.0 and I had installed the gcc-4.1 version, I changed the gcc symlink with:
sudo ln -sf /usr/bin/gcc-4.0 /usr/bin/gcc
Now the gcc symlink (used to compile the module) points to the same version of gcc used to compile the kernel: trick done!

Another useful link:
http://www.openaddict.com/documents/lkmpg/x30.html

HTH

Cheers

hi,
This is Priya here. I have installed Redhat Linux verion 9 on my system. Kernel version 2.4.20-8. Could I Please know how to compile and insert the modules given in this tutorial, with the associated makefiles.Please help me. My mail id :priyasophy_1982@yahoo.com

I appreciate for the effort took for explaining device driver writing in step by step manner...

really great work...

Thank you,
Murali

thanks man .. .. nice tutorial

regards
SuLtAn

REALLY A GREAT HELP FOR STARTERS...

ARUN

Dear sir,

This is a very good tutorial you have here. It is very cool as it explains the fundamental really well.

I tried out the first 2 section of the tutorial but am stuck.

I have created the module nothing.ko and inserted it into the kernel.
I am able to see the module using lsmod

When I tried to rmmod, the system keeps giving me the following error:
ERROR: Removing 'nothing': Device or resource busy

My lsmod | grep nothing gives me
nothing 2688 0 [permanent]

Is there a way to unload this module

Very much appreciate your help

Thanks,
Alex

My comments:

To be complete tutorial it must be accurate. It is not so.

For example, memory driver part is completely hide extensions of files and creating makefile in case if you build module from multiply files.
I think it should be added directly in article or,as minimum, in comments.

Thank you very much for posting such an astonish article for all..

God Bless all..

Thank u for giving an easy to learn tutorial about device drivers..

U can also add some more details about functions which will be more helpful...

The Tutorial help me lot

As the title says,....
Simple to understand and grasp the important things.
Thanks a lot m8
George

VERY NICE ARTICLE.

THANKS A LOT.
K.RAJASEKAR

good job

It motivates a non-driver-writer to jump into the arena that is always thought to be only for the real techies.

Really good tutorial on drivers. I challenge us to do the exercises, specifically a device that doesn't work yet.

Thanks for this important contribution!

Regards,

Hai everyone,

IN LINUX KERNEL VERSION-2.6.8-24 THE KEYBOARD DRIVER FILE KEYBOARD.C IS USED.I WOULD LIKE TO MODIFY THIS FILE SUCH THAT ON A TOGGLE KEY I WOULD LIKE TO READ DATA FROM A FILE.I USED SYSTEM CALLS LIKE OPEN,CLOSE,READ.BUT AN ERROR MESSAGE SAYING THAT THE HEADER FILE UNISTD.H INCLUDING THIS CALLS IS NOT AVAILABLE IS ENCOUNTERED.CAN ANY BODY HELP ME IN THIS CONTEXT.

good job done

First off, thanks for the great tutorial, Xavier.

I am trying to complete the LED section of the tutorial. I am running Ubuntu Server 6.10, kernel 2.6.17-10, and I removed lp, parport_pc, and parport. I have successfully compiled parlelport.ko and I can verify that the module has loaded with:
$ cat /proc/ioports
..
0378-0378 : parlelport

The circuit shows many lights blinking at boot time. After boot, bit-2 and bit-3 stay lit. They remain that way until the computer is rebooted -- or until the monitor goes to sleep. All lights go black while the monitor sleeps. The only response I can generate is that bit-1 lights after inserting parlelport.ko. It stays lit until the computer is rebooted.

The only thing that looks suspicious is this:

$:~/dev$ make -C /usr/src/linux-source-2.6.17 M=`pwd` modules
make: Entering directory `/usr/src/linux-source-2.6.17'
CC [M] /home/sam/dev/parlelport.o
/home/sam/dev/parlelport.c:31: warning: initialization from incompatible pointer type
..

Line 31 corresponds to:
write: parlelport_write

But my parlelport_write() is the same as the tutorial's.

Any pointers?

Thanks,
Sam

Fantastic Job. You have described the driver structure in simple and best manner.
Thanks.AJ

Damn useful !!! Well done buddy :-*

Hello,

Really nice tutorial...it helped me a lot..Practical Egs are good..

Keep the good work going..

This is really nice & handy tutorial.
Can this guy give similar tutorials for GCC,Shell Scripting..? It would be really good to have such tutorials..

A really handy overview!

how we write a kernel for linux? what is code of this problem?

The tutorial has been simple, I had no idea where to start with.
This has given me a good introduction to DD programming & kernel modules.
-Arjun

I am using Fedora core 5. I could not compile the very first version of "nothing" with just licence line in it.

Here is what I got.

make -C /usr/src/linux/kernel M=`pwd` modules
make: Entering directory `/usr/src/redhat/BUILD/kernel-2.6.15/linux-2.6.15.i686/kernel'
make: *** No rule to make target `modules'. Stop.
make: Leaving directory `/usr/src/redhat/BUILD/kernel-2.6.15/linux-2.6.15.i686/kernel'

Is the procedure different for Fedora? Thanks in advance.

Its really simple and informative.....

A really interesting tutorial. A little short but the main explanations are present.
Thanks.

KirgliZ

its really excellent....
amazing...
His presentation is too good and simple....

Simply simple :)

Really good work.

You wrote so clearly and easily to understand.

This tutorial gives great confidence to develop device driver for someone who is neo in this field. Great job !!!!!!!!!!

I really like it and it's written in a very nice way, thanks! :)

Great Work Sir. Its truly helpful for begineers like us. We hope to have some more from you.

Dear sir...
its really very useful.can u elaborate the drivers on keyboard also.

Very interesting. Have never really read much about driver development. Nice work.

Is there a printable version of this article? I don't find a link to one...
Thanks.

There is no such thing as "quick" and "easy" when it comes to writing drivers. Thank you :)

P.S: great tutorial

Debian etch, is now the stable release version.

I can write a similar tutorial using LEDs if anyone is interested for DOS.

I am interested in Windows NT, please give us similar simple tutotrial for Windows NT device drivers.

Great Work.

Ja

I am really impressed the way author has presented this wonderful article..he has explained in such a simple and nice manner..

Great going..

so happy hacking..

Submitted by Anonymous visitor (not verified) on Thu, 2007-05-10 12:33.

I can write a similar tutorial using LEDs if anyone is interested for DOS.

I am interested in Windows NT, please give us similar simple tutotrial for Windows NT device drivers.

Great Work.

Hi,

Its a good tutorial, I must say. You have gracefully handled this linux device driver tutorial. It would be a great benefit to newbies ,if u can come up with futher advance topics of kernel programming in your own style of writing.

Amazing tutorial ! It made me want to develop my own driver!
For French speaking people, you can find another tutorial here: http://broux.developpez.com/articles/c/driver-c-linux/

I only wish there were more tutorials like that...

The tutorial provides a nice intro to really mastering your Linux machine!

Its fantastic...!!!!!!!!!!!!!

hi,
this ia a excellent tutorial, i am using rhel5 2.6.18-8.el5
i like to learn this device driver programming but i am gating
error: linux/module.h: No such file or directory
so how to get this file. if i download this file will it work?
plz inform me princei007@yahoo.com

Good job.

I have searched and read many,

Atlast I found this tutorial, its amazingly easy to get the picture of writing a driver.

thanks
by
karthi

I wrote a small application to test the parallel port and whatever data I am writting, it is getting displayed on LED array. However when I tried to use outb from driver, it is not working. I have removed lp, parport_pc, parport modules. I put some debug messages and it is showing outb is executing properly. Even /proc/ioports is showing ports are allocated for me. I am using Fedora v6. Do you have any clue on this?

Hi
help me for writng USB device driver. from where i start my work.
thanks

Good starting point for beginners. Thank you!

I'm interested both in the source code (C, Makefile) and in the article itself.

i was running away from device drivers from last 3 weeks but this tutorial made it so easy. withing 2 hrs i had the idea wat dey r nd hw to make dem work..excellent tutorial. great work.thanx a lot

I had some trouble getting the parlelport driver working on my slackware 12 2.6.21.
The problem was that ever time I boot my machine the pin 4 led would not shut off, and
all other leds could not be turned on or off by echo or lights.o. All of this was caused by modules lp,parport,and parport_pc. The solution was to comment out the lines that load the modules in /etc/rc.d/rc.modules-[kernel version here]. There pretty hard
to miss. Add the modules to /etc/modprobe.d/blacklist did not help though I did that t and it may be part of the solution.

P.S. I love this tutorial, you wrote that it was originally written in Spanish, If English is not your first language I can't tell.

The simplest, compact tutorial to anyone to jump start on the driver.

This is the best tutorial I've read on the web. And I'm not speaking only of linux device driver tutorials.

Thanks!!