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To: Tor Egge <Tor.Egge@idt.ntnu.no>
cc: smp@bluenose.na.tuns.ca, smp@freebsd.org
Subject: Re: More info about fatal trap 12 
In-reply-to: Your message of "Fri, 06 Dec 1996 18:28:05 +0100."
             <199612061728.SAA22564@pat.idt.unit.no> 
Date: Sat, 07 Dec 1996 02:15:12 +0800
From: Peter Wemm <peter@spinner.dialix.com>
Sender: owner-smp@freebsd.org
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Tor Egge wrote:
> A closer examination of the kernel dump shows that the first page fault 
> is from the user process /bin/sh. The call stack is
[..]
> The first access to the stack by the child process failed when trying 
> to save the return value from fork.
> 
> The parent process was running on CPU #1, and the child process
> was running on CPU #0.
> 
> - Tor Egge

Hmm!!  The plot thickens!  I noticed the failing pmap_enter was at
0xefbfd000 which is the first stack page already, but I wasn't sure
if it was the initial creation, or if the stack had been paged out
and was failing on pagein.

Thank you! Confirmation of this is MOST useful!

I had redone the fork implementation some time ago to support address
space sharing for kernel supported user level threads.  I have some bad
memories about this code..  In fact, I have an idea that deserves a
closer look...

Cheers,
-Peter