From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754981Ab1HZQYl (ORCPT ); Fri, 26 Aug 2011 12:24:41 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53153 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754870Ab1HZQYk (ORCPT ); Fri, 26 Aug 2011 12:24:40 -0400 Message-ID: <4E57C8A9.1070301@zytor.com> Date: Fri, 26 Aug 2011 09:24:09 -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: Cyrill Gorcunov , Suresh Siddha , Thomas Gleixner , Ingo Molnar , Ralf Jung , 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> <20110826062224.GA3903@sun> 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 08/26/2011 09:21 AM, Bjorn Helgaas wrote: > > Is there some spec that requires all IOAPICs to be 1K aligned? I > don't doubt that's the case; I'd just like to see something more > concrete than folklore. I'm pretty sure there's some (possibly > secret) "IOAPIC architecture spec," and a section reference to it > would be nice. Even before my patch, I don't think we actually > checked or enforced any *alignment* -- we only set the size. I don't > know if it's worth it unless we have a problem it would fix, and it's > conceivable that we'd start warning about a perfectly functional > IOAPIC that's 128-byte aligned. > The PIIX3 IOAPIC decoder could only decode addresses on a 1K granularity, but I don't think that was architectural. I will try to ask. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.