Fosdem O'Reilly
2004 Edition Free and Open Source Software Developer's European Meeting


2003-12-28 - Jonathan Corbet

Linux modules

An interview conducted by Alain Buret
FOSDEM - First and traditional question : Please present yourself ...

Jonathan Corbet - I'm Jonathan Corbet, co-founder of and co-author of Linux Device Drivers, Second (and, one of these months, Third) Edition. I live in Boulder, Colorado, USA with my wife, two kids, and one dog.

FOSDEM - How and when did you start looking at device drivers ?

Jonathan Corbet -Hmm...I suppose that would be back in 1979 when I first went to the University to get my first degree (Electrical Engineering) and decided that software stuff was fun. My first real systems programming came around 1981, when Evi Nemeth let me dig into the source of an early BSD release running on the University's lone Vax 11/780. I "fixed" the virtual memory code to force large processes to page against themselves and try to preserve some RAM for everybody. That work is long since lost, and the world is better off for it.

Since then I have done driver work under VMS and a few strange variants of Unix. I got my first Linux system in 1993; I had been looking at BSD, but I noticed that the Linux-oriented newsgroups appeared to be a lot more alive. I've never looked back.

FOSDEM - You've co-written a book on writting device drivers for Linux; would you say it's a good point for someone willing to start writing kernel code and why ?

Jonathan Corbet - Certainly we have tried to make it a good starting place. Device drivers are only a small part of the larger kernel programming environment, of course, but complex drivers can require interactions with almost every other maker kernel subsystem. LDD is very much a hands-on book; we try to show how to use the interfaces and provide code that does so. If you read LDD and work through the examples, you should be well placed to dive into many parts of the kernel.

Just to be fair, I will point out that there are other good books for people wanting to learn kernel programming. I would recommend "Understanding the Linux Kernel" by Bovet and Cesati, "Linux Kernel Development" by Robert Love (which covers 2.6 interfaces), and "ia-64 Linux Kernel" by Mosberger and Eranian. All four books likely belong on an aspiring kernel hacker's bookshelf, but LDD is the only one which is available under a free license :).

FOSDEM - Can you talk to us about LWN ? Does it take you all your full time ?

Jonathan Corbet - LWN is currently the work of three people, plus a slowly increasing community of outside writers. A typical LWN Weekly Edition takes two or three days of my time to write, depending on that week's news and any special stuff I may be trying to do. Weeks when SCO goes on a rampage can be more intense. And features like the 2.6 Driver Porting Series ( take additional time.

The rest of my time is spent dealing with my mail, hacking on the site code, managing our finances, and trying to figure out how to convince more people to buy subscriptions.

LWN began, almost six years ago now, as an attempt to draw attention to our new Linux consulting business. That consulting business got dropped long ago as traffic grew, we rode the dotcom bubble, got acquired and unacquired, and even decided to shut it all down at one point. It just goes to show that you never really know where life is going to take you.

FOSDEM - Introduce in few words what you're going to talk about during your presentation ...

Jonathan Corbet - My talk will be a "what's new in 2.6" presentation - but from an insider's point of view. Rather than talk about how much better Oracle will run or the great new hardware support, I'll get into how internal programming interfaces have changed and why. Much of the work in the 2.5 development series was aimed at making the kernel safer and much more scalable; I'll cover what sort of work was required to improve on 2.4 and how that work affects kernel programmers.

FOSDEM - What are you expecting from your talk at FOSDEM and from the interactions with other developers present at the event?

Jonathan Corbet - Development-oriented conferences are always my favorite sort of Linux events. My expectation is that I will be able to get together with the people who are making free software happen and see what they are up to. It's also always fun to meet up with LWN readers and hear what the think of the work we are doing.


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