From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265468AbTLHRHS (ORCPT ); Mon, 8 Dec 2003 12:07:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265471AbTLHRHS (ORCPT ); Mon, 8 Dec 2003 12:07:18 -0500 Received: from aun.it.uu.se ([130.238.12.36]:49073 "EHLO aun.it.uu.se") by vger.kernel.org with ESMTP id S265468AbTLHRHP (ORCPT ); Mon, 8 Dec 2003 12:07:15 -0500 Date: Mon, 8 Dec 2003 18:07:11 +0100 (MET) Message-Id: <200312081707.hB8H7B85014403@harpo.it.uu.se> From: Mikael Pettersson To: linux-kernel@vger.kernel.org, nemesis-lists@icequake.net Subject: Re: APIC support on Slot-A Athlon, K6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 8 Dec 2003 05:58:59 -0600, Ryan Underwood wrote: >> Furthermore, I/O-APIC usage requires (in hardware) that the >> processor has a local APIC. > >What can the APIC support alone accomplish, without an I/O-APIC? >Just NMI watchdog and related things? (looking at CONFIG_APIC help) >Looks like I/O-APIC is the real desired feature, but a functioning local >APIC, though not very useful by itself, is a prerequisite for it. Local APIC gives you: - using the local APIC timer instead of the mobo's legacy timer - thermal management interrupts on P4s (dunno about K7s/K8s) - performance counter interrupts, which can be used as an NMI source (watchdog, profiling) or for performance analysis I/O-APIC gives you: - more interrupt vectors ==> less IRQ sharing ==> improved stability and performance - lower-overhead interrupt management - I/O-APIC NMI watchdog (another timer with NMI delivery mode)