From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265069AbTLKPA0 (ORCPT ); Thu, 11 Dec 2003 10:00:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265081AbTLKPA0 (ORCPT ); Thu, 11 Dec 2003 10:00:26 -0500 Received: from holomorphy.com ([199.26.172.102]:55781 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S265069AbTLKPAR (ORCPT ); Thu, 11 Dec 2003 10:00:17 -0500 Date: Thu, 11 Dec 2003 07:00:11 -0800 From: William Lee Irwin III To: Raul Miller Cc: linux-kernel@vger.kernel.org Subject: Re: PROBLEM: Linux 2.6.0-test11 only lets me use 1GB out of 2GB ram. Message-ID: <20031211150011.GF8039@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Raul Miller , linux-kernel@vger.kernel.org References: <3FD7FCF5.7030109@cyberone.com.au> <3FD801B3.7080604@wmich.edu> <20031211054111.GX8039@holomorphy.com> <20031211094148.G28449@links.magenta.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031211094148.G28449@links.magenta.com> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 10, 2003 at 09:41:11PM -0800, William Lee Irwin III wrote: >> You're probably thinking of 2:2 split patches. >> 2:2 splits are at least technically ABI violations, which is probably >> why this isn't merged etc. Applications sensitive to it are uncommon. >> Yes, the SVR4 i386 ELF/ABI spec literally mandates 0xC0000000 as the >> top of the process address space. On Thu, Dec 11, 2003 at 09:41:48AM -0500, Raul Miller wrote: > Apologies if I'm asking about the obvious, but... > [1] isn't 0xC0000000 at 3GB? It is. On Thu, Dec 11, 2003 at 09:41:48AM -0500, Raul Miller wrote: > [2] Even if ELF did restrict a user process to 1GB (which I'm pretty > sure it doesn't), wouldn't the kernel still be able to manage 2GB of > user memory? You have it backward. The SVR4/i386 ELF ABI specification is requiring userspace to be granted at least 3GB of address space. This does not necessarily present a restriction for the kernel; consider task gates (mingo did it by hand). On Thu, Dec 11, 2003 at 09:41:48AM -0500, Raul Miller wrote: > Probably my real question is: "what's this about 2:2 split patches"? > Basically, I thought "linux supports 2GB ram" had been been the case > since the dark ages. It's hard for me to comprehend how highmem, or 64 > bit cpus, could have much to do with a 1GB limit. You should probably ignore this thread. It's probably not relevant to you. On Thu, Dec 11, 2003 at 09:41:48AM -0500, Raul Miller wrote: > [In my fantasies, I was thinking that the system came up with only 1GB of > the memory easily usable, and that the lack of support for my hardware > meant that it couldn't be properly reconfigured. But I recognize that > I haven't spent the time researching this to see if in fact this is > the case.] Highmem support gets you this on ia32. Other architectures can support it with less overhead. On Thu, Dec 11, 2003 at 09:41:48AM -0500, Raul Miller wrote: > I am in the process of bringing up an cross compilation environment for > amd64 -- I need to do that anyways -- and I'll try building a real 64 > bit kernel to see if that helps any. If that doesn't, I guess I'll try > a couple 4G highmem kernels (one 64 bit, one 32 bit). If nothing else, > that will eat up some time... If you have such a cpu why are you bothering with highmem (or wondering if > 2GB is supported)? -- wli