Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!pt.cs.cmu.edu!sei!firth
From: firth@sei.cmu.edu (Robert Firth)
Newsgroups: comp.arch
Subject: Re: Paging page tables
Message-ID: <7728@fy.sei.cmu.edu>
Date: 3 Jul 90 20:56:04 GMT
References: <3300142@m.cs.uiuc.edu> <4137@taux01.nsc.com> <1990Jun29.213236.4888@cbnewsh.att.com> <3341@goanna.cs.rmit.oz.au>
Reply-To: firth@sei.cmu.edu (Robert Firth)
Organization: Software Engineering Institute, Pittsburgh, PA
Lines: 11

In article <3341@goanna.cs.rmit.oz.au> ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe) writes:

>One really beautiful idea is to stand the whole thing on its
>head and have your page tables map from *physical* pages to
>*virtual*, so that the space taken up by page tables is a
>fixed fraction of the size of *physical* memory.

Am I being an idiot here, or doesn't this idea have a killer
flaw: it precludes having two different virtual addresses
mapped onto the same physical address.  I can see a lot of
problems with such a restriction.