From owner-cvs-src@FreeBSD.ORG Mon Sep 20 18:14:22 2004 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5227516A522 for ; Mon, 20 Sep 2004 18:14:19 +0000 (GMT) Received: from mail1.speakeasy.net (mail1.speakeasy.net [216.254.0.201]) by mx1.FreeBSD.org (Postfix) with ESMTP id C577F43D53 for ; Mon, 20 Sep 2004 18:14:18 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 13333 invoked from network); 20 Sep 2004 18:14:18 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) encrypted SMTP for ; 20 Sep 2004 18:14:18 -0000 Received: from [10.50.40.210] (gw1.twc.weather.com [216.133.140.1]) (authenticated bits=0) by server.baldwin.cx (8.12.11/8.12.11) with ESMTP id i8KIE3lX024500; Mon, 20 Sep 2004 14:14:14 -0400 (EDT) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: "Poul-Henning Kamp" Date: Mon, 20 Sep 2004 13:55:22 -0400 User-Agent: KMail/1.6.2 References: <15147.1095545330@critter.freebsd.dk> In-Reply-To: <15147.1095545330@critter.freebsd.dk> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200409201355.23134.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on server.baldwin.cx cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/boot/i386/boot2 boot2.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Sep 2004 18:14:23 -0000 On Saturday 18 September 2004 06:08 pm, Poul-Henning Kamp wrote: > In message <200409181659.48310.jhb@FreeBSD.org>, John Baldwin writes: > >On Saturday 18 September 2004 03:08 am, Poul-Henning Kamp wrote: > >> In message <200409180207.i8I27044010045@repoman.freebsd.org>, John > >> Baldwin writ > >> > >> es: > >> >jhb 2004-09-18 02:07:00 UTC > >> > > >> > FreeBSD src repository > >> > > >> > Modified files: > >> > sys/boot/i386/boot2 boot2.c > >> > Log: > >> > A long, long time ago in a CVS branch far away (specifically, HEAD > >> > prior to 4.0 and RELENG_3), the BTX mini-kernel used paging rather > >> > than flat mode and clients were limited to a virtual address space of > >> > 16 megabytes. Because of this limitation, boot2 silently masked all > >> > physical addresses in any binaries it loaded so that they were always > >> > loaded into the first 16 Meg. Since BTX no longer has this limitation > >> > (and hasn't for a long time), remove the masking from boot2. This > >> > allows boot2 to load kernels larger than about 12 to 14 meg (12 for > >> > non-PAE, 14 for PAE). > >> > >> Does this also give us better space for isa_dma bounce buffers ? > > > >Err, I don't see how it could. This only affects how boot2 handles > > addresses in the executables it loads, it doesn't affect how the kernel > > manages memory at all. > > it was the "so that they were always loaded into the first 16 Meg" that > triggered a neuron here. > > We're seeing isa-dma bounce buffers getting hard to get hold of these > days. Humm, we've always loaded the kernel as low as possible, at least in the 3.x+ era. 3.x loaded it at 1MB IIRC, and with Bosko's changes to avoid the Intel PSE bug we switched to 4MB for non-PAE and 2MB for PAE (to avoid mapping the PSE page starting with physaddr of 0). Also, the kernel is linked such that KERNBASE maps 1:1 from 0 to KERNLOAD and beyond. If we wanted to move KERNLOAD up to, say, 16 MB, that would suck up a lot of KVA to do so. Perhaps we could make KERNBASE only map 1:1 for the first meg or so and then have it "jump" up to KERNLOAD for the second meg. Peter might be a better person to ask. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org