From owner-freebsd-current  Sun Mar 10 06:26:39 1996
Return-Path: owner-current
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.3/8.7.3) id GAA29949
          for current-outgoing; Sun, 10 Mar 1996 06:26:39 -0800 (PST)
Received: from asstdc.scgt.oz.au (root@asstdc.scgt.oz.au [202.14.234.65])
          by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id GAA29944
          for <current@freebsd.org>; Sun, 10 Mar 1996 06:26:35 -0800 (PST)
Received: (from imb@localhost)
	by asstdc.scgt.oz.au (8.6.12/BSD4.4)
	id BAA02483; Mon, 11 Mar 1996 01:25:34 +1100
From: michael butler <imb@scgt.oz.au>
Message-Id: <199603101425.BAA02483@asstdc.scgt.oz.au>
Subject: Re: AMD doesn't like SNAP! (panic: unwire: page not in pmap)
To: rgrimes@GndRsh.aac.dev.com (Rodney W. Grimes)
Date: Mon, 11 Mar 1996 01:25:33 +1100 (EST)
Cc: current@freebsd.org
In-Reply-To: <199603100445.UAA10659@GndRsh.aac.dev.com> from "Rodney W. Grimes" at Mar 9, 96 08:45:51 pm
X-Mailer: ELM [version 2.4 PL24beta]
Content-Type: text
Sender: owner-current@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk

Rodney W. Grimes writes:

> > So far three people, including myself, have reported the above panic
> > message when booting the 3/3 SNAP kernel.  All three of us have AMD DX4
> > processors (100 and 120MHz).

> Can all three of you tell me if you have A80486DX4-100NV8T's or
> A80486DX4-100SV8B's?  The difference is the SV8B is the write back
> enhanced DX4 and unless you have a motherboard that understands
> how to deal with this you are going to have a cache coherency problem
> between the internal and external cache.

I note that through a number of drivers there is mention of
cache-invalidation instructions (software-style) but none of them seem to
implement anything of this nature. Is there a problem with doing this ..
that is .. to invalidate the page(s) into which data has just been
transferred prior to the application being told that the transfer completed? 
No other cases need to be considered do they ?

	michael