From owner-freebsd-hackers  Tue Sep 25  0:55:41 2001
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Date: Tue, 25 Sep 2001 09:56:07 +0200
From: Bernd Walter <ticso@mail.cicely.de>
To: Bakul Shah <bakul@bitblocks.com>
Cc: Matt Dillon <dillon@earth.backplane.com>,
	Ian Dowse <iedowse@maths.tcd.ie>,
	Julian Elischer <julian@elischer.org>, hackers@FreeBSD.ORG
Subject: Re: VM Corruption - stumped, anyone have any ideas?
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References: <200109250027.f8P0RRk97980@earth.backplane.com> <200109250114.VAA20993@glatton.cnchost.com>
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In-Reply-To: <200109250114.VAA20993@glatton.cnchost.com>; from bakul@bitblocks.com on Mon, Sep 24, 2001 at 06:14:34PM -0700
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On Mon, Sep 24, 2001 at 06:14:34PM -0700, Bakul Shah wrote:
> FWIW, in a Unix port we did I remember putting the user
> struct *above* the kernel stack.  The stack grew down so you
> hit the red zone (the guard pages) without clobbering the
> user struct.  Since struct user _ended_ on a page boundary,
> its size was needed at locore.s assembly time but that was a
> small price to pay for the added safety.

I don't think a guard page can help here, because the page fault
handler needs a working stack.

-- 
B.Walter              COSMO-Project         http://www.cosmo-project.de
ticso@cicely.de         Usergroup           info@cosmo-project.de


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