From owner-freebsd-amd64@FreeBSD.ORG  Sat Apr  2 04:26:03 2005
Return-Path: <owner-freebsd-amd64@FreeBSD.ORG>
Delivered-To: freebsd-amd64@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 85CCE16A4CE
	for <freebsd-amd64@freebsd.org>; Sat,  2 Apr 2005 04:26:03 +0000 (GMT)
Received: from carver.gumbysoft.com (carver.gumbysoft.com [66.220.23.50])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 43B5543D2D
	for <freebsd-amd64@freebsd.org>; Sat,  2 Apr 2005 04:26:03 +0000 (GMT)
	(envelope-from dwhite@gumbysoft.com)
Received: by carver.gumbysoft.com (Postfix, from userid 1000)
	id 3AC1372DD9; Fri,  1 Apr 2005 20:26:03 -0800 (PST)
Received: from localhost (localhost [127.0.0.1])
	by carver.gumbysoft.com (Postfix) with ESMTP id 3618472DCB;
	Fri,  1 Apr 2005 20:26:03 -0800 (PST)
Date: Fri, 1 Apr 2005 20:26:03 -0800 (PST)
From: Doug White <dwhite@gumbysoft.com>
To: Gary Mu1der <gmulder@infotechfl.com>
In-Reply-To: <424DA4B3.3070703@infotechfl.com>
Message-ID: <20050401201907.U95587@carver.gumbysoft.com>
References: <f0111a98c01333b3c306c81d10294de4@khera.org>
	<Pine.SOC.4.61.0503300229560.3181@tea.blinkenlights.nl>
	<424C215E.5080201@infotechfl.com><424C4EED.5070601@infotechfl.com>
	<424D58F7.1010005@infotechfl.com><424DA4B3.3070703@infotechfl.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: freebsd-amd64@freebsd.org
Subject: Re: Tyan k8sr lockups
X-BeenThere: freebsd-amd64@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Porting FreeBSD to the AMD64 platform <freebsd-amd64.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-amd64>,
	<mailto:freebsd-amd64-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-amd64>
List-Post: <mailto:freebsd-amd64@freebsd.org>
List-Help: <mailto:freebsd-amd64-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-amd64>,
	<mailto:freebsd-amd64-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 02 Apr 2005 04:26:03 -0000

On Fri, 1 Apr 2005, Gary Mu1der wrote:

> I have isolated the crash to the following dd command:
>
> 	dd if=/dev/mem of=/dev/null bs=1024k skip=4040 count=1

Reading from random places in /dev/mem will cause unpredicatable behavior.
Memory at that offset is in PCI memory-mapped device space, and reading
from there may disrupt the PCI bridge, enable or disable interrupts, or
worse.

-- 
Doug White                    |  FreeBSD: The Power to Serve
dwhite@gumbysoft.com          |  www.FreeBSD.org