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" 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.