Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261863AbVEEERB (ORCPT ); Thu, 5 May 2005 00:17:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261873AbVEEERA (ORCPT ); Thu, 5 May 2005 00:17:00 -0400 Received: from fmr22.intel.com ([143.183.121.14]:61675 "EHLO scsfmr002.sc.intel.com") by vger.kernel.org with ESMTP id S261863AbVEEEQ6 (ORCPT ); Thu, 5 May 2005 00:16:58 -0400 Subject: RE: [RFC][PATCH] i386 x86-64 Eliminate Local APIC timer interrupt From: Len Brown To: Venkatesh Pallipadi Cc: Zwane Mwaikambo , Andrew Morton , Linus Torvalds , mingo@elte.hu, linux-kernel , "Shah, Rajesh" , John Stultz , Andi Kleen , Asit K Mallick In-Reply-To: <88056F38E9E48644A0F562A38C64FB60049EE972@scsmsx403.amr.corp.intel.com> References: <88056F38E9E48644A0F562A38C64FB60049EE972@scsmsx403.amr.corp.intel.com> Content-Type: text/plain Organization: Message-Id: <1115266581.7644.52.camel@d845pe> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.3 Date: 05 May 2005 00:16:21 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1289 Lines: 31 On Fri, 2005-04-29 at 22:43, Pallipadi, Venkatesh wrote: > The patch as it is should handle 8259 case using the regular APIC > timer. It only adds broadcast when IOAPIC is used for timer > interrupt. While they don't need the broadcast capability of this patch, uniprocessors do need the change to stop using LAPIC timer if they support C3 (as virtually all laptops do). It was a mistake to allow using the LOC on a uniprocessor in the first place -- as the UP system runs perfectly fine with timers coming in on IRQ0 and doesn't need another interrupt. Re: SMP using i8259 While Linux in ACPI mode allows "noapic" on SMP, it isn't recommended. It is there for comparisons, debugging, and to work-around the odd broken system. It is an exception configuration, and supporting it should in no way impact the design for other 99.99% normal systems. Indeed, note that SMP systems using i8259 instead of IOAPIC is explicity forbidden by MPS, and thus would probably fail the compatibility test for your favorite high volume binary OS. -Len - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/