Message-ID:	<328510D9.1F39@ananke.amu.edu.pl>
Date:	Sun, 10 Nov 1996 00:16:41 +0100
From:	Mark Habersack <grendel AT ananke DOT amu DOT edu DOT pl>
Reply-To:	grendel AT ananke DOT amu DOT edu DOT pl
Organization:	Home, sweet home
MIME-Version:	1.0
To:	gbdflyer AT flash DOT net
CC:	djgpp AT delorie DOT com
Subject:	Re: True Processor-aided PM multitasking
References:	<3283D4F5 DOT 79E8 AT flash DOT net>

Glenn Dunham wrote:

> One problem:  I know of no DJGPP functions that allow allocation of GDT
> selectors.  (DPMI only allows LDT allocation.)  One possible solution
> would be to copy the GDT to a 64kb segment (I believe the max. GDT size
> is 64K, or 8192 quadword descriptors) and repoint the GDTR to it.  (FSDB
> reported a GDT of only about 32 descriptors while I was running one of
> my programs.)  This would allow the program to have plenty of space to
> allocate TSS selectors, etc....
> 
> Is that the only way?
Under DOS that would be fairly easy, provided you'll be able to allocate
some code that runc in Ring 0. With CWSDPMI it's easy, but what about
the rest of DPMI servers? OTOH, I don't think that te solution you
suggest would work under WinXX. They will just not allow any access to
GDT from a DOS VM/subsystem. You'd have to write a VxD that'd interface
between DOS and Win kernel. Even having that VxD, I'm not sure whether
there are any exported APIs to manupulate GDT in Windows.

-- 
**************************************************************************
You tell me I'm drunk then you sit back and smug a while convinced that
you're right, that you're still in command of your senses. I laugh at
your superior attitude, your insincere platitudes will make me throw up.
The sooner you realise I'm perfectly happy if I'm left to decide the
company I choose.
********************** http://ananke.amu.edu.pl/~grendel
*****************

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