Date: Fri, 1 Dec 2000 09:08:46 -0800 (PST) From: Richard Hodges <rh@matriplex.com> To: freebsd-hackers@FreeBSD.ORG Subject: Re: Per-process kernel stack size Message-ID: <Pine.BSF.4.10.10012010858470.76299-100000@mail.matriplex.com> In-Reply-To: <200012010619.eB16JuF02371@mass.osd.bsdi.com>
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On Thu, 30 Nov 2000, Mike Smith wrote:
> > The routines have a nesting of 10-12 functions having 10-100 lines each.
> > Could you tell us what is the minimum available run time memory in the
> > per-process kernel stack for running these routines?
> You can generally assume that you have about 4k of kernel stack (you will
> normally have more, but don't count on it 8).
I'm sure this is pretty obvious, and has already occured to most everyone
else, but...
Wouldn't it be a simple matter to set a global pointer to the stack
base (lowest address) when switching context, so that the running
code could know exactly how close it is to the limits? Maybe this
would not be used in release code, but could be another tool for
auditing suspicious code.
Even better, maybe the stack could be set on a non-contiguous virtual
address so that any overflow would trigger a fault? I would *much*
rather have the machine grind to a halt with a relevant message than
see mysterious data corruption.
Of course, neither of these would be worthwhile once I stop writing
code with bugs ;-)
All the best,
-Richard
-------------------------------------------
Richard Hodges | Matriplex, inc.
<title> | 769 Basque Way
rh@matriplex.com | Carson City, NV 89706
775-886-6477 | www.matriplex.com
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