From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754633Ab1HZBnN (ORCPT ); Thu, 25 Aug 2011 21:43:13 -0400 Received: from terminus.zytor.com ([198.137.202.10]:35036 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754411Ab1HZBnI (ORCPT ); Thu, 25 Aug 2011 21:43:08 -0400 Message-ID: <4E56F9E5.4000005@zytor.com> Date: Thu, 25 Aug 2011 18:41:57 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0 MIME-Version: 1.0 To: Bjorn Helgaas CC: Suresh Siddha , Thomas Gleixner , Ingo Molnar , Ralf Jung , Cyrill Gorcunov , Yinghai Lu , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/2] x86, ioapic: Reserve only 128 bytes for IOAPICs References: <20110825230539.5355.13851.stgit@bhelgaas.mtv.corp.google.com> <1314315225.16133.30.camel@sbsiddha-desk.sc.intel.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/25/2011 05:17 PM, Bjorn Helgaas wrote: > > If the OS allocated the next 128 bytes to another device, it sounds > like it would cause a conflict on Intel boxes. This must be an area > that differs between vendors. I haven't seen a spec that mentions 256 > bytes as the required minimum MMIO size for IOAPICs, and apparently > the AMD IOAPIC decodes 240 bytes or fewer. > For what it's worth, it's probably a bad idea on x86 for the OS to allocate addresses in the 0xFExxxxxx range... -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.