From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267403AbUHDUKK (ORCPT ); Wed, 4 Aug 2004 16:10:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267402AbUHDUKK (ORCPT ); Wed, 4 Aug 2004 16:10:10 -0400 Received: from umhlanga.stratnet.net ([12.162.17.40]:17641 "EHLO umhlanga.STRATNET.NET") by vger.kernel.org with ESMTP id S267403AbUHDUKE (ORCPT ); Wed, 4 Aug 2004 16:10:04 -0400 To: "Martin J. Bligh" Cc: Andrew Morton , Jens Axboe , eric@cisu.net, kernel@kolivas.org, barryn@pobox.com, swsnyder@insightbb.com, linux-kernel@vger.kernel.org Subject: Re: HIGHMEM4G config for 1GB RAM on desktop? X-Message-Flag: Warning: May contain useful information References: <200408021602.34320.swsnyder@insightbb.com> <410FA145.70701@kolivas.org> <20040804060625.GE10340@suse.de> <200408040614.30820.eric@cisu.net> <20040804130707.GN10340@suse.de> <20040804120633.4dca57b3.akpm@osdl.org> <210450000.1091647829@flay> From: Roland Dreier Date: Wed, 04 Aug 2004 13:09:11 -0700 In-Reply-To: <210450000.1091647829@flay> (Martin J. Bligh's message of "Wed, 04 Aug 2004 12:30:29 -0700") Message-ID: <527jseis2g.fsf@topspin.com> User-Agent: Gnus/5.1006 (Gnus v5.10.6) XEmacs/21.4 (Security Through Obscurity, linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-OriginalArrivalTime: 04 Aug 2004 20:09:11.0681 (UTC) FILETIME=[E857F710:01C47A5E] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Martin> I had a patch for a config option, ported forward by Martin> someone at IBM (I forget who, possibly Dave) from Andrea's Martin> original. I think we finally decided (in consultation with Martin> Andrea) we could drop the complicated stuff he had in the Martin> asm code, so it's pretty simple ... something like this: Am I just being dense, or is this patch solving a different problem from "do I really have to turn on HIGHMEM4G just to get the last 128MB of my 1GB of RAM?" It seems to me that none of the PAGE_OFFSET values offered (the patch in allows PAGE_OFFSET to be set to 0xe0000000, 0xc0000000, 0x80000000 or 0x40000000, in addition to the 4G/4G value of 0x02000000) are exactly what someone with 1 GB of RAM wants. They'd be forced to go down to a 2G/2G split which cheats userspace of quite a bit of address space (admittedly with only 1 GB of RAM, a process bigger than 2 GB is a bit of a stretch). In any case a 2.75G/1.25G split as suggested earlier works fine with 1 GB of RAM. Also I notice that Con's patch modifies vmlinux.ld.S to update the kernel base address, while this patch doesn't. Is that intentional or is does the patch depend on some other patches that use the defines in page.h somehow as controlled by the following change? +AFLAGS_vmlinux.lds.o += -include $(TOPDIR)/include/asm-i386/page.h Thanks, Roland