Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757770Ab0G2Tz7 (ORCPT ); Thu, 29 Jul 2010 15:55:59 -0400 Received: from smtp108.prem.mail.ac4.yahoo.com ([76.13.13.47]:36868 "HELO smtp108.prem.mail.ac4.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755287Ab0G2Tz6 (ORCPT ); Thu, 29 Jul 2010 15:55:58 -0400 X-Yahoo-SMTP: _Dag8S.swBC1p4FJKLCXbs8NQzyse1SYSgnAbY0- X-YMail-OSG: JzCH1PIVM1k6jHZyMRguU4BuTzRwplpAbvQ46xDoZD3pKdk 2kZmbh67Mwduvp0IzMRgNjtg01UKlMo70TQNWwn4r4gY0adXXj0bKOD_E8QD hKmAbpx8MEV6CuZnIqGNDqNejw3.C7qSR9x8fojiio6LdcbKJXVZ4trd_Xyx IyllAE6UGBUKrSnF4ao_bCp28pKoZhyiTwSXVyrFDcXzAry6xhYufG0nsRfY 0p0_QuqOzCAjQk7M2UC1vfVXeQU4B X-Yahoo-Newman-Property: ymail-3 Date: Thu, 29 Jul 2010 14:55:53 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@router.home To: Russell King - ARM Linux 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 In-Reply-To: <20100729183320.GH18923@n2100.arm.linux.org.uk> Message-ID: References: <20100728155617.GA5401@barrios-desktop> <20100728225756.GA6108@barrios-desktop> <20100729161856.GA16420@barrios-desktop> <20100729170313.GB16420@barrios-desktop> <20100729183320.GH18923@n2100.arm.linux.org.uk> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 835 Lines: 19 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. -- 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/