From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752885Ab0BAVwt (ORCPT ); Mon, 1 Feb 2010 16:52:49 -0500 Received: from terminus.zytor.com ([198.137.202.10]:45966 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751907Ab0BAVws (ORCPT ); Mon, 1 Feb 2010 16:52:48 -0500 Message-ID: <4B674C82.9050703@zytor.com> Date: Mon, 01 Feb 2010 13:49:54 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Thunderbird/3.0.1 MIME-Version: 1.0 To: Suresh Siddha CC: "Maciej W. Rozycki" , "ebiederm@xmission.com" , "yinghai@kernel.org" , "mingo@elte.hu" , "linux-kernel@vger.kernel.org" Subject: Re: [patch 2/2] x86, irq: use 0x20 for the IRQ_MOVE_CLEANUP_VECTOR instead of 0x1f References: <20100114002118.436172066@sbs-t61.sc.intel.com> <20100114002118.521826763@sbs-t61.sc.intel.com> <4B5C00EB.3000208@zytor.com> <1265059497.2802.178.camel@sbs-t61.sc.intel.com> In-Reply-To: <1265059497.2802.178.camel@sbs-t61.sc.intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/01/2010 01:24 PM, Suresh Siddha wrote: > > As we are using the code from 2.6.28 and no one noticed/complained about > this issue for more than 1.5 years, probably the pentium APIC issue is > not wide-spread. > I *think* it's applicable to all CPUs Pentium III or earlier (but not Pentium 4 -- I'm unsure about the Pentium M.) I don't know about non-Intel CPUs; I have a vague memory of the Transmeta Efficeon (the only Transmeta chip with an APIC) *not* having this limitation. The exact reference is SDM vol 3A 10.8.4, page 10-41 [rev 033US Dec 2009]: For the P6 family and Pentium processors, the IRR and ISR registers can queue no more than two interrupts per priority level, and will reject other interrupts that are received within the same priority level. However, section 10.8.2 bullet 3 on page 10-38 (and the flowchart on page 10-37) indicate that such an interrupt is returned to the IOAPIC for a later retry, i.e. it's not lost. As such, it's not clear to me from reading the SDM that there is actually a problem here... -hpa