> >>Figuring out is the probem. Every one has to reverse engeneer existing
> >>drivers if he wants to know how to write a new one.
> > Well, you can always read the code in subr_autoconf.c that runs it all. 
> This is exactely the answer I wanted to hear. ;-)
> "RTFSC" (Read The F*** Source Code) is not an adequate answer to a
> newbe, that has no knowledge about the _concept_. There should be some
> kind of doc that explains the basic concept (like the man pages in
> sction 9). 

There are two papers which explain the workings of the xBSD configuration
system, one of which is referred to by name on the config(8) man page, the
other of which appeared recently on the NetBSD web site.

You can start with

	Building 4.4BSD Kernels with Config by Samuel J. Leffler and
	Michael J. Karels

I found this paper by searching with Google; I think it was over on the
FreeBSD web site.  It gives a good overview and tutorial of the config
system from the system managers standpoint, with a little bit about
internals.

Follow this with

	Device Configuration in 4.4 BSD by Chris Torek

This paper can be found at

	http://www.netbsd.org/Documentation/kernel/config-torek.ps

This latter paper goes into the internals of the configuration system in
considerable detail. 

Keep in mind that these papers describe the configuration system as it
existed a few years ago.  There have been some enhancements since then, but
the basic structure remains unchanged.

After careful study of these papers, I think you'll find subr_autoconf.c and
the device drivers much more enlightening -- I did.

Regards,

David Querbach
Real-Time Systems Inc.