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To: "Jeffrey D. Wheelhouse" <jdw@wwwi.com>
cc: freebsd-stable@freebsd.org
Subject: Re: Trap 12/supervisor read, page not present 
In-reply-to: Your message of "Sun, 16 Jun 1996 12:30:49 PDT."
             <199606161932.MAA03996@voltimand.csd.wwwi.com> 
From: David Greenman <davidg@Root.COM>
Reply-To: davidg@Root.COM
Date: Sun, 16 Jun 1996 17:22:05 -0700
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>At 05:34 AM 6/15/96 -0700, you wrote:
>>   This appears to be a "known" bug. I didn't notice in your original message;
>>was this with 2.1R or a recent SUP of -stable? 
>
>Both, with -stable sup'd on Friday.  I resupped yesterday and got 
>rev 1.22.4.4 of vm_map.c, and built a new kernel with that (old one
>was 1.22.4.2).
>
>Now the machine reboots every few hours with nothing at all in the
>dmesg and savecore reports "no core dump."  Perhaps there is something
>else I am doing wrong?  Bad hardware?  My machine isn't pounding nearly
>as hard as, say, ftp.cdrom.com.

   I've been running this same kernel code for the past 40 hours while running
my "thrash" regression test (which consists of about a dozen parallel
compiles, a fork-exec-exit endless loop, some filesystem traversal scripts,
top, and about a half dozen other things that excercise networking and other
parts of the system. I haven't had any problems. I'm running a variant of this
code on wcarchive (ftp.cdrom.com) that is slightly older and doesn't contain
all of the fixes, and it's been up now for 5 days (load is around 700 users
much of the time).
   ...so I'm at a loss to explain your instability problems. It would help if
you could describe the hardware you're using, your kernel configuration, and
the kind of load that is on the machine.

>I have avoided DDB until now because since I've never used FreeBSD before,
>and I know the BSDI kernel debugger can cause the system to wait for
>operator input before rebooting.  Now I will break down and install it.
>I will speak again if that helps me learn something.  In the meantime, if
>you have any advice, or know of any other way in which I can help, please
>let me know.

   If you're not having some kind of hardware problem, then the instability
must be caused by the specific set things that are running on the machine.

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project