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From: shap@sfsup.UUCP (J.S.Shapiro)
Newsgroups: comp.sys.intel
Subject: Re: Copy-on-write
Message-ID: <867@sfsup.UUCP>
Date: Tue, 25-Nov-86 03:18:36 EST
Article-I.D.: sfsup.867
Posted: Tue Nov 25 03:18:36 1986
Date-Received: Tue, 25-Nov-86 10:08:01 EST
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Organization: AT&T Information Systems, Summit N.J.
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> 
>    If you don't have per-segment page tables, then you don't have hardware
> support for copy-on-write of pages, only segments.  I consider this a
> pretty serious deficiency.
> 

Oh, crap. Read the manual before you betray your ignorance and save all of
us the trouble of correcting it. You can do write protection on a
page-by-page basis. Since all of the segments end up mapped into a flat
address space, you protect them/unprotect them at that level, including,
possibly, sharing a page between two segments.

The *pages* can be write protected.