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Date:	Mon, 13 Dec 2004 11:28:41 +0200 (EET)
From:	Esa A E Peuha <peuha AT cc DOT helsinki DOT fi>
Sender:	peuha AT sirppi DOT helsinki DOT fi
To:	djgpp-workers AT delorie DOT com
Subject:	Re: Bison 1.875 (release 2)
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On Sat, 11 Dec 2004, Eli Zaretskii wrote:

> The only limitation of this technique, IIRC, is that you can only
> unmap page-aligned regions of memory.  This leaves the portion of
> memory between the end of the allocated buffer and the next page
> unprotected on the hardware level.

YAMD can align either the beginning or the end of each allocated buffer
at page boundary, so this is no problem, although you have to run the
program twice to test it thoroughly.  The default is to align the end of
each buffer, because access after the end is more common than before the
beginning.  (If pointers could have individual selectors, it would be
possible to use the same technique under any DPMI host since even pure
DPMI 0.9 supports selector limits, but unfortunately GCC doesn't produce
such code.)

-- 
Esa Peuha
student of mathematics at the University of Helsinki
http://www.helsinki.fi/~peuha/

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