RE: DPL_3 IDT entries

• To: "Rogelio M. Serrano Jr." <rogelio@evoserve.com>, <oskit-users@fast.cs.utah.edu>
• Subject: RE: DPL_3 IDT entries
• From: "Alastair Reid" <reid@cs.utah.edu>
• Date: Thu, 16 Nov 2000 14:33:32 -0700
• Importance: Normal
• In-reply-to: <3A09544A.84BC553E@evoserve.com>
• Sender: owner-oskit-users@fast.cs.utah.edu

Rogelio M. Serrano Jr. writes:
> Why are most of the default IDT entries  have a DPL 0? What issues are
> involved with DPL 3 IDT entries?

If I understand you correctly, you're asking why we run in privileged mode (as
though we were an OS kernel) instead of in unprivileged mode (as though we were
a normal application)?

The answer is that some of the OSKit components need to run in that mode.  I'm
not sure exactly which ones but the most likely suspects are the SVM component
(which manipulates the MMU) and code taken from environments which use DPL 0 (I
believe/imagine this includes Linux and FreeBSD device drivers).

That said, I imagine (but don't know for sure) that most OSKit code couldn't
care less which mode it runs in so you probably could build interesting OSKit
kernels using DPL 3 entries though you'll have to check the standard (and
somewhat tortuous) bootstrap sequence carefuly.


--
Alastair Reid

• Re: DPL_3 IDT entries
• From: Simon Nieuviarts <Simon.Nieuviarts@inrialpes.fr>

• DPL_3 IDT entries
• From: "Rogelio M. Serrano Jr." <rogelio@evoserve.com>

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