If you’re not in Ring 0 you may as well be in Ring 3. There’s little reason to have rings 1 & 2 … and I don’t think there are any CPUs around these days that are optimized for anything but a binary choice of supervisor (ring 0) and user (ring 3).
-p
-----Original Message-----
From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of Tim Roberts
Sent: Wednesday, March 28, 2007 12:44 PM
To: Windows System Software Devs Interest List
Subject: Re: [ntdev] Re:Driver Programming Fundamentals/Philosophy, was: Re: Calling NdisRequest() from ProtoclBi
Maxim S. Shatskih wrote:
> Microsoft could have required that all drivers run in ring 1 instead of ring
> 0,
>…at the cost of portability. Sorry.
I don’t understand your point, Maxim. Portability between what and what?
Having drivers run in ring 1 would be a very sensible architecture. The
only thing in ring 0 would be some small and trusted kernel core, with
drivers in a somewhat protected world around it. There’s some small
additional performance cost for calling across rings, but there are ways
to handle that.
–
Tim Roberts, xxxxx@probo.com
Providenza & Boekelheide, Inc.
Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256
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