Date: Wed, 28 Jul 93 09:13:10 -0400
From: DJ Delorie <dj AT ctron DOT com>
To: rri!potter AT vtserf DOT cc DOT vt DOT edu, sandmann AT arion DOT rice DOT edu,
        djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Accessing memory-mapped devices

> > least alowing for protection).  I would doubt that it would give a program
> > access to all of memory, but of course it could virtualize it all. 

> I checked the docs - it only guarantees the first 1M.

More study shows that the mechanism that DPMI 0.9 uses to do this is
as follows:

	* Request that the physical memory be mapped somewhere in linear
	address space.

	* Allocate a selector

	* Tell the selector to point to the linear address space.

The problem is that djgpp isn't geared towards using selectors.  Even
supporting this type of operation under non-dpmi is not trivial.  It
seems an important feature anyway.

Any Ideas?