[WinMac] Re: SFM Ring Zero
Dan Schwartz(expresso[at]snip.net)
Wed, 20 Jan 1999 02:20:42 -0500
Glen,
When I saw the number of rings in my NT reference manual, I was a bit
suspicious that he got it backward. I'll ask this over on the AlphaNT
listserv.
[Sign up at: <http://www.alphant.com>.]
Moving the graphics drivers down to Ring 0 was why NT4 had so much better
screen redraw performance than NT 3.51. And with goodies like (QuickTime
clone) DirectX, which directly accesses the hardware, the trend is to
remove the last vestiges of "protection."
One of my favorite phrases to describe NT's protection, which although
quite good can sometimes get a bit out of hand, is to equate it to using a
tin can for a condom. :)
At 02:19 PM 1/19/99 -0600, Glen Martin replied to me:
>Dan Schwartz <expresso@snip.net> wrote:
>
>> Thanks for the info! BTW, only Ring 3 (user mode) and Ring 0
(kernel mode,
>> a/k/a supervisor mode) is implemented in NT. The reason is that although
>> there are Rings 3 through 0 in the x86, only Rings 3 and 0 exist on the
>> Alpha (Per Sean Daily).
>
>You have that backwards. ix86 has only two memory protection modes.
>Alpha has four...
>
>I hope that Windows 2000 does indeed get the graphics drivers out of
>kernel memory space. The hit in reliability going from NT 3.51 to 4.0
>was painful...
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