*BSD News Article 97827


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Problem with 2.2.1 Install !!!
Date: 16 Jun 1997 20:29:15 GMT
Organization: Private BSD site, Dresden
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"Jordan K. Hubbard" <jkh@FreeBSD.org> wrote:

> > Straight after the ed0 probe (which should probe the 3Com board) I
> 
> Only one type of 3Com card (the 3c503) - the more generally encountered
> 3Com products actually probe with the ep driver.  Are you sure of this
> one?

Well, there are even more 3Com drivers :) (vx, eg, el), but he wrote
about a 3C503, so the ed0 is correct.

> > received the following rather large (and awe inspiring/scary) message.
> > 
> >         Fatal trap 12 : page fault while in kernel mode
> >         fault virtual address   = 0xefc00000
> >         fault code              = supervisor read, page not present
> 
> Hmmm.  That's definitely weird - it sure would be nice to know exactly
> which driver triggers this.

Right after ed0, the probe should continue with ed1.  The fault is
inside function kvtop(), a very short function converting a KVA
(kernel virtual address) into a physical address, or simpler call it a
page map read.  (It's actually in the inlined call to
pmap_kextract().)

This means the page tables on your machine are corrupted.  Oh well, i
don't say it's not the os's fault, but it's not unlikely a memory
problem either.  At any rate, it will require serious investigation
before it's possible to spot this (since the time when the page table
is corrupted and the spot where the crash happens might be very
different).

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)