Dynamic Kernels: Modularized Device Drivers
The Kernel Korner columns of the following months will introduce further points of module-writing. Code samples can be found inside the kernel and on ftp sites near you.
In particular, what I describe is based on my personal experience with device drivers: both the ceddrv-0.xx and cxdrv-0.xx resemble the code I describe. Georg Zezschwitz and I wrote the ceddrv, which drives a lab interface (A/D, D/A, bells and whistles). The cxdrv driver is simpler, and drives a memory-mapped frame grabber. The latest versions of both drivers are available on ftp://iride.unipv.it/pub/linux for public ftp. ceddrv is also on tsx-11.mit.edu, while cxdev is on sunsite.unc.edu in apps/video.
There are quite a few books about device drivers out there, but they're often too system-specific and describe an awkward interface—Linux is easier. Generic books about Unix internals and the kernel source are the best teachers. I'd suggest to get one of the following:
Maurice J. Bach, The Design of the UNIX Operating System, Prentice Hall, 1986
Andrew S. Tanenbaum, Operating Systems: Design and Implementation, Prentice Hall, 1987
Andrew S. Tanenbaum, Modern Operating Systems, Prentice Hall, 1992
Alessandro Rubini (email@example.com) is taking his PhD course in computer science and is breeding two small Linux boxes at home. Wild by his very nature, he loves trekking, canoeing, and riding his bike.