From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755508AbZASRIr (ORCPT ); Mon, 19 Jan 2009 12:08:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751549AbZASRIg (ORCPT ); Mon, 19 Jan 2009 12:08:36 -0500 Received: from relay1.sgi.com ([192.48.179.29]:34954 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751706AbZASRIf (ORCPT ); Mon, 19 Jan 2009 12:08:35 -0500 Message-ID: <4974B38F.5060503@sgi.com> Date: Mon, 19 Jan 2009 09:08:31 -0800 From: Mike Travis User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Jack Steiner CC: Ingo Molnar , LKML , "H. Peter Anvin" , Thomas Gleixner , Yinghai Lu , "Maciej W. Rozycki" Subject: Re: [PATCH] x86: put trigger in to detect mismatched apic versions. References: <49704DF6.8040205@sgi.com> <20090116092540.GC4305@elte.hu> <4970C984.30202@sgi.com> <20090116223011.GB3899@elte.hu> <497116A8.5080900@sgi.com> <20090117030752.GB127262@sgi.com> <20090118190849.GB858@elte.hu> <20090118212553.GA164127@sgi.com> In-Reply-To: <20090118212553.GA164127@sgi.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 Jack Steiner wrote: > On Sun, Jan 18, 2009 at 08:08:49PM +0100, Ingo Molnar wrote: >> * Jack Steiner wrote: >> >>>> Btw, I checked with our UV architect and the problem is that we need a >>>> 16 bit apic id which is what caused the MAX_APICS to be bumped to 32k. >>>> The lower 8 bits are the normal apic id, and the upper bit relate to >>>> the node. This means cpu 0 on node 0 has the same apic id as cpu 0 on >>>> node 1, etc. I also asked about whether we could rely on always >>>> having >>> Not strictly true. The apicids in the ACPI tables are always globally >>> unique across the entire system. Because of the size of UV systems, UV >>> needs 16 bit apicids. This fits in the ACPI apicid id/eid fields. Ahh, I did mean to say this applied to the lower 8 bits only. >>> >>> The actual processor apicid register is unfortunately only 11 bits and >>> there are some restrictions on the actual values loaded into the apicid >>> register. This is for x2apics only, yes? >>> >>> If we can put unique ids into the apicid register, we do. If we can't, >>> the function that reads the apicid will automatically supply the rest of >>> the bits. Most of the kernel is unaware that the processor apicid >>> register may have only a subset of the bits that are in the ACPI tables. >> apicid remapping is something we need/want, so we cannot remove that >> array. But it would be nice to offload such properties to the percpu area >> instead - is there any reason why that is hard? The local apic is attached >> to a CPU in any case. Is there some early init reason that complicates >> this? > > I can't think of any reason why it could not be moved into > the percpu data area. Mike??? WHich array? There are two now, the x86_cpu_to_apicid and x86_bios_cpu_apicid that are in the percpu area? (Maybe it's time to find out why there are two. ;-) Thanks, Mike