From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261305AbTJRBl3 (ORCPT ); Fri, 17 Oct 2003 21:41:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261297AbTJRBl3 (ORCPT ); Fri, 17 Oct 2003 21:41:29 -0400 Received: from fw.osdl.org ([65.172.181.6]:48023 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261294AbTJRBl1 (ORCPT ); Fri, 17 Oct 2003 21:41:27 -0400 Date: Fri, 17 Oct 2003 18:41:11 -0700 From: Andrew Morton To: Matt Chapman Cc: davidm@hpl.hp.com, bjorn.helgaas@hp.com, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] prevent "dd if=/dev/mem" crash Message-Id: <20031017184111.22eaa13d.akpm@osdl.org> In-Reply-To: <20031018013137.GA16845@cse.unsw.EDU.AU> References: <200310171610.36569.bjorn.helgaas@hp.com> <20031017155028.2e98b307.akpm@osdl.org> <200310171725.10883.bjorn.helgaas@hp.com> <20031017165543.2f7e9d49.akpm@osdl.org> <16272.34681.443232.246020@napali.hpl.hp.com> <20031017174955.6c710949.akpm@osdl.org> <20031018013137.GA16845@cse.unsw.EDU.AU> X-Mailer: Sylpheed version 0.9.4 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Matt Chapman wrote: > > It *does* signal a fault, in the form of a machine check. On other > architectures I'm familiar with this is usually implemented as an > interrupt, but the idea is similar - when the system bus controller > detects a bad address on the bus, it returns all 1s (for a read) and > signals an interrupt. I see. That seems OK. At least it means that software can implement a probing function and that the time interval between hot unplug and handling the unplug interrupt can be managed appropriately.