Chapter 2. 11h30 - NLKD: The Novell Linux Kernel Debugger

NLKD: The Novell Linux Kernel Debugger

Clyde Griffin and Jan Beulich

project: http://forge.novell.com/modules/xfmod/project/?nlkd

The Novell Linux Kernel Debugger is a very, very interesting project and I'm very much looking forward to using it... once I can. As interesting as this project is, it can only currently be used with a heavily modified SuSE kernel; patches are not yet available to be applied to a generic kernel.org kernel.

That being the way it is, the NLKD is still very interesting. They gave a very thorough demonstration of the debugger (that's hard to fully explain in text) which demonstrated many of this tool's capabilities. The debugger has a lot of functionality built into it which make it obvious that it is something that is being used by actual kernel developers. I got the impression that this debugger is something that's been around inside Novell for a while and has simply been ported to work with Linux; although I can't remember if that's something I read, something I heard, or something my brain made up all on its own. :-)

One of the more impressive features of the debugger occurs when you set your X Window driver to be VESA. In this mode you can be working in X Windows and when the debugger comes up it can handle your screen; when you're done with the debugger you can return to X Windows without having you screen all messed up.

As a debugging tool the NLKD has all the bells and whistles one would expect from a powerful debugging tool. The one feature that I liked a lot was the ability to walk a code path (with all the proper jumps and returns) but without any of the code actually executing.

The debugger has been designed to be very modular. Starting with a debugger core, interface units are attached that allow debugging to occur either locally or remotely via the GDB remote protocol (depending on which interface module is in use). Source level debugging is only available if you're using the remote tool.

I'm very much looking forward to being able to use this debugger with my kernel.org kernels!