Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754494Ab0ALAds (ORCPT ); Mon, 11 Jan 2010 19:33:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754419Ab0ALAdr (ORCPT ); Mon, 11 Jan 2010 19:33:47 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:45630 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754401Ab0ALAdr (ORCPT ); Mon, 11 Jan 2010 19:33:47 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Tue, 12 Jan 2010 09:30:31 +0900 From: KAMEZAWA Hiroyuki To: Wu Fengguang Cc: "Zheng, Shaohui" , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "ak@linux.intel.com" , "y-goto@jp.fujitsu.com" , Dave Hansen , "x86@kernel.org" Subject: Re: [PATCH - resend] Memory-Hotplug: Fix the bug on interface /dev/mem for 64-bit kernel(v1) Message-Id: <20100112093031.0fc6877f.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100111124303.GA21408@localhost> References: <20100108124851.GB6153@localhost> <20100111124303.GA21408@localhost> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.7.1 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1270 Lines: 37 On Mon, 11 Jan 2010 20:43:03 +0800 Wu Fengguang wrote: > > > + /* if add to low memory, update max_low_pfn */ > > > + if (unlikely(start_pfn < limit_low_pfn)) { > > > + if (end_pfn <= limit_low_pfn) > > > + max_low_pfn = end_pfn; > > > + else > > > + max_low_pfn = limit_low_pfn; > > > > X86_64 actually always set max_low_pfn=max_pfn, in setup_arch(): > > [Zheng, Shaohui] there should be some misunderstanding, I read the > > code carefully, if the total memory is under 4G, it always > > max_low_pfn=max_pfn. If the total memory is larger than 4G, > > max_low_pfn means the end of low ram. It set > > > max_low_pfn = e820_end_of_low_ram_pfn();. > > The above line is very misleading.. In setup_arch(), it will be > overrode by the following block. > Hmmm....could you rewrite /dev/mem to use kernel/resource.c other than modifing e820 maps. ? Two reasons. - e820map is considerted to be stable, read-only after boot. - We don't need to add more x86 special codes. Thanks, -Kame -- 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/