Hi
> userland code.  Clearly, I have missed something.... can anyone give
> me a hint?  BTW yes, I _do_ have the ioctl call in the cdevsw entry, I
> have verified it is there in cdevsw using ddb.
Well that would have been my first question :-)

What "command" are you calling your ioctl with. Are you sure the 
specific command is not being "handled" at a "higher level" (I 
assume this can happen?) and not going through to your ioctl? Try 
defining your own ioctl commands (see sys/filio.h for example of 
defining your own...).

Hope this helps. I'm a "beginner" in these matters myself....

Cheers
Dave