user doing direct I/O

[Brian Chapman]

glenn at extro.ucc.su.OZ.AU (Glenn Geers) writes:

>	<...>  However, you still don't get around the system
>call overhead. This can only be achieved by issuing ioctl(fd, IOPRIVL, 1)
>(1 system call, finished) and then banging away at i/o ports in assembler. For
>*fast* graphics <...>

Yes,  direct use of IN & OUT 386 instructions is possible from user
space after giving the [EV]GA_IOPRIVL command.  BUT...  this is
only for use with the video I/O ports.  You will find that Xenix
lets to access all I/O ports but SCO _Unix_ behaves in the more
restrictive manner.
	-- Chapman
-- 
Brian Chapman		uunet!sco!chapman
Pay no attention to the man behind the curtain!