From owner-freebsd-hackers  Thu Nov  6 10:49:42 1997
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From: Terry Lambert <tlambert@primenet.com>
Message-Id: <199711061847.LAA28069@usr03.primenet.com>
Subject: Re: >64MB
To: mike@smith.net.au (Mike Smith)
Date: Thu, 6 Nov 1997 18:47:53 +0000 (GMT)
Cc: tony@dell.com, tlambert@primenet.com, jamil@trojanhorse.ml.org,
        hackers@FreeBSD.ORG
In-Reply-To: <199711061242.XAA00382@word.smith.net.au> from "Mike Smith" at Nov 6, 97 11:12:16 pm
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> How do you copy the kernel into memory > 1M in real mode?  If you could
> elaborate on this (and how to *stay* in real mode while running over 
> 1M, ie. so that the kzip pass and subsequent real-mode startup 
> requirements could be met), I'd be *very*happy*

There are several ways to do this.  The main one uses a call that drops
into protected mode, changes a 64k mapping at the top of the 1M
you can get at, and goes back to protected mode.

You can see a nice example of this in your config.sys on most DOS
machines, where you probably load an EMS, XMS, or DPMI driver so
DOS (and more likely, Windows 3.x) can use memory above 1M.

There are a couple other tricks you can do, but they pretty much
require Appendix H functions, and not all clone processors can
do that.

I highly recommend the "MindShare" book "Protected Mode Software
Architecture" (I think that is the title).


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.