Xref: news2.mv.net comp.os.msdos.djgpp:4815
From: Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: remapping the vga
Date: Mon, 10 Jun 1996 17:37:58 CDT
Organization: Rice University, Houston, Texas
Lines: 18
Message-ID: <31bca3c6.sandmann@clio.rice.edu>
References: <31BC39F0 DOT 65A AT unm DOT edu>
Reply-To: sandmann AT clio DOT rice DOT edu
NNTP-Posting-Host: clio.rice.edu
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

> is there any other way to map 64k of memory to 0xa0000 without using
> __djgpp_map_physical_memory?  im wondering because the only way this 
> works is if the program runs with cwsdpmi, and not under windows cuz its 
> not dpmi 1.0.  or is it possible to 'force' a program to use cwsdpmi 
> even if it is under windows?

There is no way to bypass windows without writing a .VXD.

If we were to abandon using LD to create our binary images, and re-write
the loader to support dynamic fixups for all addresses, you could 
make all addresses 0 based, map the 4Gb area in a single selector,
see the interrupt table at 0, VGA at 0xa0000, etc.  Having null pointers
scrogg the interrupt table is sort of moving backwards, however, from
a point of stability.  This would be a huge rewrite of much of the
code also, and noone with the skills to do it has the interest and
extra spare time.  The code for DXEs does a dynamic loading at any address,
so there is nothing which hasn't been done, it would just be a matter of
putting it all together.