From owner-freebsd-hardware@FreeBSD.ORG Fri Nov 28 13:39:01 2008 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D5BF1106564A for ; Fri, 28 Nov 2008 13:39:01 +0000 (UTC) (envelope-from avg@icyb.net.ua) Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id B602E8FC13 for ; Fri, 28 Nov 2008 13:39:00 +0000 (UTC) (envelope-from avg@icyb.net.ua) Received: from odyssey.starpoint.kiev.ua (alpha-e.starpoint.kiev.ua [212.40.38.101]) by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id PAA24342; Fri, 28 Nov 2008 15:28:36 +0200 (EET) (envelope-from avg@icyb.net.ua) Message-ID: <492FF203.5060405@icyb.net.ua> Date: Fri, 28 Nov 2008 15:28:35 +0200 From: Andriy Gapon User-Agent: Thunderbird 2.0.0.18 (X11/20081124) MIME-Version: 1.0 To: freebsd-hardware@freebsd.org, freebsd-hackers@freebsd.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Subject: dd if=/dev/mem can hang a machine? X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Nov 2008 13:39:01 -0000 I have a new machine with DG33TL mainboard (ICH9/G33). In a course of some hacking I ran dd if=/dev/mem ... to scan all memory, this caused the machine to hang. I tried to reproduce and this is 100% reproducible. I am not used to such behavior. In older days I could scan all the memory without any issues. Could this be related to some modern form of memory-mapped IO? Or to Intel Management Engine (that seems t bite into DRAM)? Or something else? Just wondering. -- Andriy Gapon