From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752321Ab0IBGv4 (ORCPT ); Thu, 2 Sep 2010 02:51:56 -0400 Received: from smtpbg55.qq.com ([64.71.138.44]:58719 "HELO smtpbg55.qq.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751484Ab0IBGvz (ORCPT ); Thu, 2 Sep 2010 02:51:55 -0400 X-QQ-mid: esmtp4t1283410311t157t9016 X-QQ-SSF: 0000000000000010F16200000000000 Message-ID: <4C7F4984.1060703@qq.com> Date: Thu, 02 Sep 2010 14:51:48 +0800 From: gaoqiang <834555262@qq.com> User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.11) Gecko/20100713 Thunderbird/3.0.6 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: dear list Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I'm a newbie and got some question when learning the linux kernel about a macro: page_to_pfn(pg) I traced its definition,and finally got that: #define __page_to_pfn(page) ((unsigned long)((page) - mem_map) + ARCH_PFN_OFFSET) why hot ((unsigned long)((page)-mem_map + ARCH_PFN_OFFSET)/sizeof (struct page)