Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756111Ab0G2VOK (ORCPT ); Thu, 29 Jul 2010 17:14:10 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:52073 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754203Ab0G2VOJ (ORCPT ); Thu, 29 Jul 2010 17:14:09 -0400 Date: Thu, 29 Jul 2010 22:13:10 +0100 From: Russell King - ARM Linux To: Christoph Lameter Cc: Minchan Kim , KAMEZAWA Hiroyuki , Milton Miller , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mel Gorman , Johannes Weiner , Kukjin Kim Subject: Re: [PATCH] Tight check of pfn_valid on sparsemem - v4 Message-ID: <20100729211310.GA28330@n2100.arm.linux.org.uk> References: <20100728155617.GA5401@barrios-desktop> <20100728225756.GA6108@barrios-desktop> <20100729161856.GA16420@barrios-desktop> <20100729170313.GB16420@barrios-desktop> <20100729183320.GH18923@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: 1054 Lines: 22 On Thu, Jul 29, 2010 at 02:55:53PM -0500, Christoph Lameter wrote: > On Thu, 29 Jul 2010, Russell King - ARM Linux wrote: > > > And no, setting the sparse section size to 512kB doesn't work - memory is > > offset by 256MB already, so you need a sparsemem section array of 1024 > > entries just to cover that - with the full 256MB populated, that's 512 > > unused entries followed by 512 used entries. That too is going to waste > > memory like nobodies business. > > SPARSEMEM EXTREME does not handle that? > > Some ARMs seem to have MMUs. If so then use SPARSEMEM_VMEMMAP. You can map > 4k pages for the mmap through a page table. Redirect unused 4k blocks to > the NULL page. We're going over old ground which has already been covered in this very thread. I've no compunction to repeat the arguments. -- 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/