From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757837Ab1KKNMi (ORCPT ); Fri, 11 Nov 2011 08:12:38 -0500 Received: from db3ehsobe001.messaging.microsoft.com ([213.199.154.139]:54075 "EHLO DB3EHSOBE001.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756499Ab1KKNMg convert rfc822-to-8bit (ORCPT ); Fri, 11 Nov 2011 08:12:36 -0500 X-SpamScore: -3 X-BigFish: VS-3(zz98dKzz1202hzzz2dh2a8h668h839h8e2h8e3h) X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPVD:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-FB-SS: 0, From: Tabi Timur-B04825 To: Benjamin Herrenschmidt CC: Tabi Timur-B04825 , "Moffett, Kyle D" , "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" , Baruch Siach , Kumar Gala , Wood Scott-B07421 , Paul Gortmaker , Paul Mackerras , Wolfram Sang , Grant Likely , Anatolij Gustschin , Paul Bolle , Sonny Rao Subject: Re: [RFC PATCH 02/17] powerpc: Split up PHYS_64BIT config option to fix "select" issues Thread-Topic: [RFC PATCH 02/17] powerpc: Split up PHYS_64BIT config option to fix "select" issues Thread-Index: AQHMnzzdhs3Oy1OOpUirq+wMQb9GQpWmJMiAgACN2oD//6CVAIABLeEAgACMJQA= Date: Fri, 11 Nov 2011 13:12:31 +0000 Message-ID: <4EBD1F3E.2040402@freescale.com> References: <4E42AB6F.1050900@freescale.com> <1320883635-17194-3-git-send-email-Kyle.D.Moffett@boeing.com> <4EBBD9DF.6080100@freescale.com> <501ACA94-491F-43A7-9DCF-485BEE824DD5@boeing.com> <4EBC00D2.2030208@freescale.com> <1320987054.21206.55.camel@pasglop> In-Reply-To: <1320987054.21206.55.camel@pasglop> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:7.0.1) Gecko/20110928 Firefox/7.0.1 SeaMonkey/2.4.1 x-originating-ip: [68.203.10.197] Content-Type: text/plain; charset=US-ASCII Content-ID: Content-Transfer-Encoding: 7BIT MIME-Version: 1.0 X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Benjamin Herrenschmidt wrote: > For PHYS_64BIT, I'm not 100% certain at this point what the best > approach it. It should clearly be fixed and hidden for real 64-bit. As > for the rest, should it be user selectable ? I have been unable to convince our BSP teams that the minor performance improvement of a 32-bit kernel vs 36-bit is not worth the hassle. We ship a lot of lower-end e500 systems that will never have more than 2GB of memory. The P1022DS is an example. We ship 32-bit and 36-bit versions of U-Boot, the kernel, and the device tree. I recently added code to U-boot to detect if you have a mismatched U-Boot and device tree, because it is so easy to mess that up. I would like nothing more than to abandon 32-bit for all e500, but I don't see Freescale allowing that any time soon. -- Timur Tabi Linux kernel developer at Freescale