Date:	Thu, 19 Jun 1997 10:18:50 +0300 (IDT)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To:	Conrad Wei-Li Song <conradsong AT mail DOT utexas DOT edu>
cc:	djgpp AT delorie DOT com
Subject:	Re: Exception handling question...
In-Reply-To:	<199706190256.WAA24601@delorie.com>
Message-ID:	<Pine.SUN.3.91.970619101820.27193D-100000@is>
MIME-Version:	1.0

On Wed, 18 Jun 1997, Conrad Wei-Li Song wrote:

> I'm confused about why it is necessary to lock memory used by an
> exception handler.  In the case where code resides in a currently
> paged-out location in memory, wouldn't a page fault occur and resume
> exception handling properly (assuming that the interrupt flag isn't
> cleared.

Page fault is an exception.  Having an exception inside another
exception is a Bad Thing.  Additionally, the first exception might
have happened during a DOS call (like when your program was reading a
file or printing to the screen) and the page fault handler also calls
DOS to read the swap file.  Since DOS is non-reentrant, this is a
definite no-no.

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