From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267047AbUBMQGl (ORCPT ); Fri, 13 Feb 2004 11:06:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267051AbUBMQGl (ORCPT ); Fri, 13 Feb 2004 11:06:41 -0500 Received: from obsidian.spiritone.com ([216.99.193.137]:18594 "EHLO obsidian.spiritone.com") by vger.kernel.org with ESMTP id S267047AbUBMQGj (ORCPT ); Fri, 13 Feb 2004 11:06:39 -0500 Date: Fri, 13 Feb 2004 08:05:14 -0800 From: "Martin J. Bligh" To: Sean Neakums , Nagy Tibor cc: xela@slit.de, mochel@osdl.org, bmoyle@mvista.com, orc@pell.chi.il.us, linux-kernel@vger.kernel.org Subject: Re: HIGHMEM Message-ID: <64200000.1076688313@[10.10.2.4]> In-Reply-To: <6uvfmbktrj.fsf@zork.zork.net> References: <402CC114.8080100@dell633.otpefo.com> <6uvfmbktrj.fsf@zork.zork.net> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> I am sorry, I have found your e-mail address in >> ./arch/i386/kernel/setup.c. I have the problem below since a year, and >> there is no solution yet. I guess, the problem is about e820. The >> problem exists in 2.4.x and also in 2.6.1. >> >> We have two Dell Poweredge servers, an older one (PowerEdge 6300) and a >> newer one (PowerEdge 6400). Both servers have 4GB RAM, but the Linux >> kernel uses about 500MB less memory in the newer machine. > > I may be talking through my hat, but I think that in this case you > need to select the option for support of 64G highmem. If I recall, > "4G highmem" refers not to the total amount to the memory, but to the > highest physical address that can be accessed. That's exactly correct. Whether the gain of 500MB of RAM is worth the overhead of PAE is another question ... but that's how to do it ;-) M.