From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262070AbVADAlw (ORCPT ); Mon, 3 Jan 2005 19:41:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262005AbVADAhs (ORCPT ); Mon, 3 Jan 2005 19:37:48 -0500 Received: from one.firstfloor.org ([213.235.205.2]:49847 "EHLO one.firstfloor.org") by vger.kernel.org with ESMTP id S261980AbVADAez (ORCPT ); Mon, 3 Jan 2005 19:34:55 -0500 To: colin@coesta.com Cc: linux-kernel@vger.kernel.org Subject: Re: Max CPUs on x86_64 under 2.6.x References: <44438.202.154.120.74.1104760841.squirrel@www.coesta.com> From: Andi Kleen Date: Tue, 04 Jan 2005 01:34:50 +0100 In-Reply-To: <44438.202.154.120.74.1104760841.squirrel@www.coesta.com> (Colin Coe's message of "Mon, 3 Jan 2005 22:00:41 +0800 (WST)") Message-ID: User-Agent: Gnus/5.110002 (No Gnus v0.2) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org "Colin Coe" writes: > Hi all > > Why is the number of CPUs on the x86_64 architecture only 8 but under i386 > it is 255? > > I've searched the list archives and Google but can't find an answer. Post 2.6.10 x86-64 will support more CPUs. 2.6.10 actually does too, but the Kconfig hadn't been changed then. Previously there was an 8 CPU APIC driver limit, however it turned out later that it doesn't apply to some Opteron machines. -Andi