From owner-freebsd-arch@FreeBSD.ORG Mon Nov 8 18:58:12 2004 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 47E2116A4CE for ; Mon, 8 Nov 2004 18:58:12 +0000 (GMT) Received: from mail4.speakeasy.net (mail4.speakeasy.net [216.254.0.204]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0326543D39 for ; Mon, 8 Nov 2004 18:58:12 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 8486 invoked from network); 8 Nov 2004 18:58:11 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) encrypted SMTP for ; 8 Nov 2004 18:58:11 -0000 Received: from [10.50.41.235] (gw1.twc.weather.com [216.133.140.1]) (authenticated bits=0) by server.baldwin.cx (8.12.11/8.12.11) with ESMTP id iA8Iw71U019779; Mon, 8 Nov 2004 13:58:08 -0500 (EST) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: Willem Jan Withagen Date: Mon, 8 Nov 2004 13:53:15 -0500 User-Agent: KMail/1.6.2 References: <418AB176.9030604@withagen.nl> <200411051400.34684.jhb@FreeBSD.org> <418BE3D2.2030205@withagen.nl> In-Reply-To: <418BE3D2.2030205@withagen.nl> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200411081353.15394.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on server.baldwin.cx cc: freebsd-arch@FreeBSD.org Subject: Re: Booting questions .... X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Nov 2004 18:58:12 -0000 On Friday 05 November 2004 03:34 pm, Willem Jan Withagen wrote: > John Baldwin wrote: > > [about the loader having flat addressspace....] > > >>But is it unsegmented? (perhaps I have a wrong idea of a flat address > >>space) > > > > Yes, it is unsegmented. You can translate physical addresses to virtual > > addresses using PTOV() and vice versa using VTOP(). > > I've run accross these calls, just need to figure out how to work them. > > >>What I mean with this is that I can iterate from 0xa000 to 0xffffffff > >> with a "char *p" and do test_bytes( 0xa000, 0xffffffff, 0xff). (assuming > >> this all has memory) > > > > Yes. > > Would be nice.... > > >>Next is then which ranges are valid to test, and then things really start > >>to get complicated and arch dependant. Which is why I ended up in > >> machdep.c right after the setting up of the memory ranges. > > > > Heh, the above memory mapping is also i386 specific. Alpha only has a > > small bit of memory mapped in the loader, same with sparc64, etc. > > Ehhhh, again more reasons to put this in the kernel, or something that > closely resembles a kernel. Well, part of the problem there is that the early kernel code is all MD anyway. I think your best bet really is to write your own mini-kernel that the loader can load to do this, but it will require MD stubs for early bootstrapping as well as some kind of API for mapping a page so you can test it and then unmap it, which is required for x86 machines with > 4GB of RAM for example. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org