From:	kurt DOT skauen AT funcom DOT com (Kurt Skauen)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: DPMI incorporation...
Date:	Mon, 06 Jan 1997 12:33:21 GMT
Organization:	Funcom production A/S
Lines:	26
Message-ID:	<852554000.109630@araga.funcom.com>
References:	<199612310023 DOT BAA23998 AT math DOT amu DOT edu DOT pl>
Reply-To:	kurt DOT skauen AT funcom DOT com
NNTP-Posting-Host:	araga.funcom.com
Cache-Post-Path:	araga.funcom.com!unknown AT pcshare-44 DOT funcom DOT com
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

"Mark Habersack" <grendel AT ananke DOT amu DOT edu DOT pl> wrote:

>2. Memory protection. On 286 memory has been protected by means of 
>segment sizes and location stored in descriptors in either LDT or 
>GDT. i386 enables another protection scheme: each page, information 
>on which is stored in Page Directories and Directory Tables, can have 
>its own set of protection bits - this allows for a very minute memory 
>protection. i486 extends the scheme even more by making possible 
>creation of read-only pages for all users of the OS (including the OS 
>itself - unlike on i386 where OS, i.e. software running at the Ring 
>0, can read/write any area of memory).

HOW DO YOU DO THAT?? Sorry for the screaming. It's just that I am
working on a multitasking operating system, and are now doing the
memory protection/virtual memory stuff, and found it quite anoing that
I was unable to protect the kernal from itself.  I only got
documentation on the i386, so I was not aware that it was possible, to
write-protect memory for supervisor code on a i486. Is there any good
documentation on the i486 around? Somting like the 386INTEL.TXT from
Intel.


Kurt. 	Programmer Funcom/R&D
The above expressions is not ment to represent Funcom.

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