From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030664AbXDPOdq (ORCPT ); Mon, 16 Apr 2007 10:33:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030666AbXDPOdq (ORCPT ); Mon, 16 Apr 2007 10:33:46 -0400 Received: from shawidc-mo1.cg.shawcable.net ([24.71.223.10]:24312 "EHLO pd3mo1so.prod.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030664AbXDPOdp (ORCPT ); Mon, 16 Apr 2007 10:33:45 -0400 Date: Mon, 16 Apr 2007 08:33:26 -0600 From: Robert Hancock Subject: Re: 4GB Physical. Less than 3GB in Linux. In-reply-to: To: Jeff Chua Cc: lkml Message-id: <46238936.3060501@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jeff Chua wrote: > I've noticed that with 4GB physical ram, I'm only see 3098000 MB on > the Dell 745, and 3107056MB on the IBM X60s. > > I've tested with CONFIG_HIGHMEM4G=y, CONFIG_HIGHMEM64G=y, > CONFIG_X86_PAE=y, but nothing makes any difference. Chipset limitation. It uses up most of the MMIO region above 3GB preventing RAM from being mapped there, and doesn't support remapping the covered RAM to above 4GB. Nothing the kernel can do about it. -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/