Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758165AbZKDUOJ (ORCPT ); Wed, 4 Nov 2009 15:14:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758131AbZKDUOI (ORCPT ); Wed, 4 Nov 2009 15:14:08 -0500 Received: from eddie.linux-mips.org ([78.24.191.182]:37554 "EHLO eddie.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758132AbZKDUOH (ORCPT ); Wed, 4 Nov 2009 15:14:07 -0500 Date: Wed, 4 Nov 2009 21:15:20 +0100 From: Ralf Baechle To: Wu Zhangjin Cc: Arnaud Patard , linux-mips@linux-mips.org, LKML , huhb@lemote.com, yanh@lemote.com, Zhang Le , Thomas Gleixner , Nicholas Mc Guire , zhangfx@lemote.com, liujl@lemote.com Subject: Re: [PATCH -queue v0 1/6] [loongson] add basic loongson-2f support Message-ID: <20091104201520.GA26504@linux-mips.org> References: <1257332652.8716.5.camel@falcon.domain.org> <20091104111957.GA13549@linux-mips.org> <1257348226.16033.4.camel@falcon.domain.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1257348226.16033.4.camel@falcon.domain.org> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1574 Lines: 35 On Wed, Nov 04, 2009 at 11:23:46PM +0800, Wu Zhangjin wrote: > > We have other systems where 32-bit kernel support is just remarkably ugly. > > We've dropped 32-bit support for the SGI IP32 aka O2 - nobody seems to even > > have really noticed that. The Sibyte systems would be good candidates to do > > the same as accesses to outside the 32-bit address space are needed very > > frequently. > > > > So, we really remove the 32bit support? > > 1312 config CPU_LOONGSON2 > 1313 bool > 1314 select CPU_SUPPORTS_32BIT_KERNEL --> remove it? > 1315 select CPU_SUPPORTS_64BIT_KERNEL > 1316 select CPU_SUPPORTS_HIGHMEM > > If you all agree, I will send a new patch to remove the above line and > resend the corresponding patches without 32bit support, and removed the > relative CONFIG_64BIT lines in the patches too. If you need highmem with 32-bit (and with Loongson systems I assume that virtually all systems will have enough RAM to require that) then you're almost certainly better off going 64-bit. Highmem takes a performance toll which for some workloads can be very significant. And while highmem won't go away any time soon it's nothing kernel performance is being tuned for, so it's only going to get worse into the future so I'd not waste time on highmem unless I have to. Ralf -- 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/