Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263942AbUFCLry (ORCPT ); Thu, 3 Jun 2004 07:47:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263944AbUFCLrx (ORCPT ); Thu, 3 Jun 2004 07:47:53 -0400 Received: from chaos.analogic.com ([204.178.40.224]:53120 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id S263942AbUFCLru (ORCPT ); Thu, 3 Jun 2004 07:47:50 -0400 Date: Thu, 3 Jun 2004 07:46:58 -0400 (EDT) From: "Richard B. Johnson" X-X-Sender: root@chaos Reply-To: root@chaos.analogic.com To: reg@dwf.com cc: Brian Gerst , linux-kernel@vger.kernel.org, reg@orion.dwf.com, linux@horizon.com, reg@orion.dwf.com Subject: Re: Intel 875 Motherboard cant use 4GB of Memory. In-Reply-To: <200406030232.i532W4eU008705@orion.dwf.com> Message-ID: References: <200406030232.i532W4eU008705@orion.dwf.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1478 Lines: 40 On Wed, 2 Jun 2004 reg@dwf.com wrote: > > > > Wrong. Ever since the Pentium Pro, x86 processors have had 36-bit > > *physical* addressing. This is why PAE-mode paging was introduced. A > > sane BIOS would configure the memory controller to remap some of the > > memory above 4G physical to allow for memory mapped devices. It sounds > > like this board's BIOS isn't doing that, or at least not reporting it in > > the e820 map. > > > Hummm. > > Let me restate the fact that I dont understand how PC hardware works, but > I can understand how the area for PCI devices has to come out of the > KERNEL address space, but why does it have to be subtracted from the USER > address space too? > > > -- > Reg.Clemens > reg@dwf.com It isn't. However some of the user address-space is used by the kernel so a user can't address 32 bits of (data) space either. The sum of the address-spaces that each user can access can far exceed all the RAM and certainly 32-bits of space. That's why we have swap-files. Cheers, Dick Johnson Penguin : Linux version 2.4.26 on an i686 machine (5570.56 BogoMips). Note 96.31% of all statistics are fiction. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/