From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753750AbaA3TZM (ORCPT ); Thu, 30 Jan 2014 14:25:12 -0500 Received: from merlin.infradead.org ([205.233.59.134]:59607 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752728AbaA3TZK (ORCPT ); Thu, 30 Jan 2014 14:25:10 -0500 Message-ID: <52EAA714.3080809@infradead.org> Date: Thu, 30 Jan 2014 11:25:08 -0800 From: Randy Dunlap User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Andiry Xu , linux-kernel@vger.kernel.org CC: Andiry Xu , Linux MM Subject: Re: [BUG] Description for memmap in kernel-parameters.txt is wrong References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [adding linux-mm mailing list] On 01/30/2014 08:52 AM, Andiry Xu wrote: > Hi, > > In kernel-parameters.txt, there is following description: > > memmap=nn[KMG]$ss[KMG] > [KNL,ACPI] Mark specific memory as reserved. > Region of memory to be used, from ss to ss+nn. Should be: Region of memory to be reserved, from ss to ss+nn. but that doesn't help with the problem that you describe, does it? > Unfortunately this is incorrect. The meaning of nn and ss is reversed. > For example: > > Command Expected Result > memmap 2G$6G 6G - 8G reserved 2G - 8G reserved > memmap 6G$2G 2G - 8G reserved 6G - 8G reserved Are you testing on x86? The code in arch/x86/kernel/e820.c always parses mem_size followed by start address. I don't (yet) see where it goes wrong... > Test kernel version 3.13, but I believe the issue has been there long ago. > > I'm not sure whether the description or implementation should be > fixed, but apparently they do not match. I prefer to change the documentation and leave the implementation as is. -- ~Randy