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Date:      Wed, 27 Dec 2006 15:14:12 -0500
From:      Mike Meyer <mwm-keyword-freebsdhackers2.e313df@mired.org>
To:        Jan Knepper <jan@digitaldaemon.com>
Cc:        freebsd-isp@freebsd.org, Tim McCullagh <tim@halenet.com.au>, Mario Theodoridis <mario-dated-1167617290.71c9c2@schmut.com>, FreeBSD Hackers <FreeBSD-Hackers@freebsd.org>
Subject:   Re: 6.1-RELEASE / 6.2 Kernel Crash...
Message-ID:  <17810.54292.139339.466850@bhuda.mired.org>
In-Reply-To: <4592690B.7080800@digitaldaemon.com>
References:  <45918F6E.90006@digitaldaemon.com> <004c01c7293b$d5e03b40$6500a8c0@laptopt> <4591CB3C.1060902@digitaldaemon.com> <200612261808.08984.mario@schmut.com> <4592690B.7080800@digitaldaemon.com>

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In <4592690B.7080800@digitaldaemon.com>, Jan Knepper <jan@digitaldaemon.com> typed:
> FreeBSD 5.x branch run on that machine for almost 2 years without a 
> problem and magically the same time period in *hours* that I upgrade the 
> machine I get hardware problems too? Not an impossible coincidence, but 
> not very likely...

Or it could be that you have a hardware problem in hardware that
wasn't used by 5.x but is by 6.x.

<Storytime>
I had an 11/750 that ran BSD 4.2 for years with no problems. When I
tried to upgrade it to BSD 4.3, it would reliably panic in namei
during the boot process. We had about a dozen 750s, and this was our
test machine - so none of them were going to be upgraded until this
got fixed, deadline or no.

Stepping through namei in the debugger showed that one of the
instructions in the function prelude was changing a high bit in a
register it wasn't supposed to touch at all. In 4.2, the register was
unused, because namei got passed a handful of arguments. In 4.3, it
got passed a pointer to a struct with some of that information in it,
and the pointer wound up in said register. Dereferencing the pointer
caused the panic.

A motherboard replacement solved the problem.

</Storytime>

	<mike
-- 
Mike Meyer <mwm@mired.org>		http://www.mired.org/consulting.html
Independent Network/Unix/Perforce consultant, email for more information.



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