From owner-freebsd-questions@FreeBSD.ORG Thu Aug 30 21:51:02 2007 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 86D0016A420 for ; Thu, 30 Aug 2007 21:51:02 +0000 (UTC) (envelope-from bobby@susanne.tomatoseed.org) Received: from susanne.tomatoseed.org (adsl-76-241-164-190.dsl.sfldmi.sbcglobal.net [76.241.164.190]) by mx1.freebsd.org (Postfix) with ESMTP id F3FFC13C45B for ; Thu, 30 Aug 2007 21:51:01 +0000 (UTC) (envelope-from bobby@susanne.tomatoseed.org) Received: from susanne.tomatoseed.org (localhost [127.0.0.1]) by susanne.tomatoseed.org (8.13.8/8.13.8) with ESMTP id l7ULWAHM011145 for ; Thu, 30 Aug 2007 17:32:10 -0400 (EDT) (envelope-from bobby@susanne.tomatoseed.org) Received: from localhost (bobby@localhost) by susanne.tomatoseed.org (8.13.8/8.13.8/Submit) with ESMTP id l7ULW9nQ011142 for ; Thu, 30 Aug 2007 17:32:10 -0400 (EDT) (envelope-from bobby@susanne.tomatoseed.org) Date: Thu, 30 Aug 2007 17:32:09 -0400 (EDT) From: User Bobby To: freebsd-questions@freebsd.org Message-ID: <20070830172127.M11085@susanne.tomatoseed.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Subject: 4gb address space limitation for i386 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Aug 2007 21:51:02 -0000 I have an IBM xSeries 350 4xPIII with 5.5gb of RAM, and see that only about 3.5gb is being used under the i386 port. I've been looking through the archives to try and figure out what the root of the problem is and I amn't quite sure I know which part of the situation is the real problem. Is it a limitation of the i386 port? That is to say, if there were a specific PIII (i686?) port, would this problem be overcome? Or is it a hardware limitation? Is it necessary to use a not-clean method to access the extra address space (is this what PAE is?), and there's no clean way around it, regardless of the port? I was looking at building a PAE kernel, but was discouraged by the lack of usb and certain SCSI support, both of which I'd really like to have (in the case of SCSI, need to have). Is this lack of support because of an inherent difficulty in the hardware, or could it be overcome in a stable way with modification of the device driver code? My basic (and very hypothetical) question - if I had unlimited time and knowledge (I have limited both), what direction would I take to get access to all 5.5gb of RAM on this particular computer? Thank you, Bob