Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!sdd.hp.com!wuarchive!uunet!viusys!uxui!unislc!harem!wes
From: wes@harem.clydeunix.com (Barnacle Wes)
Newsgroups: comp.unix.sysv386
Subject: Re: Does WINDOWS run under VP/ix?
Summary: Um, probably not...
Message-ID: <314@harem.clydeunix.com>
Date: 31 May 91 22:17:28 GMT
References: <1991May17.010926.338@gorgon.uucp> <1991May17.105152.1870@metro.ucc.su.OZ.AU>
Organization: Clyde's Harem; Eunuchs Guard
Lines: 23

In article <1991May17.105152.1870@metro.ucc.su.OZ.AU>, glenn@suphys.physics.su.OZ.AU (Glenn Geers) writes:
> Don't forget UNIX runs in one 4 Gb segment. I think it is possible to have
> a supervisor running in another segment that could switch between UNIX and
> windows 3.0 in protected mode. The segment selector is 16 bits wide so you
> get 65536 segments (i.e. the 386 can address up to 2^16*2^32 bytes of (very)
> virtual memory). What I'm saying is that you could run a lot of different
> protected mode operating systems if you had a suitable supervisor program
> to manage segment swapping - I'd hate to wait for a 4Gb swap! - and memory
> fragmentation and compaction would be a pain!

I think you'd have to re-write the VM handler code in the unix kernel
pretty extensively to do this; all of the REAL operating systems :-)
running in such a system are going to want control of the Global
Descriptor Table, and I think the GDT would differ greatly from system
to system.  The 386 allows you multiple virtual 8086s, but not multiple
virtual 386s.

	Wes Peters
-- 
#include <std/disclaimer.h>                               The worst day sailing
My opinions, your screen.                                   is much better than
Raxco had nothing to do with this!                        the best day at work.
     Wes Peters:  wes@harem.clydeunix.com   ...!sun!unislc!harem!wes