> >> 	All you had to do to outb() to the lpt port is 
>  
> >> 		(1) #include <machine/pio.h>
> >> 		(2) open("/dev/io", O_RDWR)   (have to be root of course)
> >> 		(3) outb(0x3bc, VALUE)
>  
> >> 	I never had to mess with i386_iopl.
> 
> >Unless I'm mistaken, this is a deprecated interface, and will cease to
> >be supported at some point in the future.
> 
> Aha! Useful information I didn't know.
> 
> I guess it sure makes sense. It has occured to me that opening /dev/io was
> a little too all-or-nothing.

Slightly worse than that, I think: it's a security hole in the making.

consider, if I/O access enabled by open of /dev/io, and I/O access
revoke by close:

UNIX driver semantics say that the driver sees every open -- and
therefore frob bits in the proc doing the opening, if it wants -- but
only sees the _last_ close.

"oops."