From owner-freebsd-ppc@FreeBSD.ORG  Tue Apr 10 17:28:03 2007
Return-Path: <owner-freebsd-ppc@FreeBSD.ORG>
X-Original-To: freebsd-ppc@freebsd.org
Delivered-To: freebsd-ppc@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 7078D16A402
	for <freebsd-ppc@freebsd.org>; Tue, 10 Apr 2007 17:28:03 +0000 (UTC)
	(envelope-from grehan@freebsd.org)
Received: from dommail.onthenet.com.au (dommail.OntheNet.com.au [203.13.70.57])
	by mx1.freebsd.org (Postfix) with ESMTP id 0848313C4C1
	for <freebsd-ppc@freebsd.org>; Tue, 10 Apr 2007 17:28:02 +0000 (UTC)
	(envelope-from grehan@freebsd.org)
Received: from [10.33.24.110] (nat-198-95-226-228.netapp.com [198.95.226.228])
	by dommail.onthenet.com.au (MOS 3.7.5a-GA)
	with ESMTP id CRQ25399 (AUTH peterg@ptree32.com.au);
	Wed, 11 Apr 2007 03:27:57 +1000 (EST)
Message-ID: <461BC8FF.1010506@freebsd.org>
Date: Tue, 10 Apr 2007 10:27:27 -0700
From: Peter Grehan <grehan@freebsd.org>
User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.8b) Gecko/20051014
MIME-Version: 1.0
To: Philip Schulz <ph.schulz@gmx.de>
References: <4084.50499.qm@web8407.mail.in.yahoo.com> <461BBC5A.80005@gmx.de>
In-Reply-To: <461BBC5A.80005@gmx.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: freebsd-ppc@freebsd.org
Subject: Re: Help regarding the second stage loader
X-BeenThere: freebsd-ppc@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Porting FreeBSD to the PowerPC <freebsd-ppc.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-ppc>,
	<mailto:freebsd-ppc-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-ppc>
List-Post: <mailto:freebsd-ppc@freebsd.org>
List-Help: <mailto:freebsd-ppc-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-ppc>,
	<mailto:freebsd-ppc-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 10 Apr 2007 17:28:03 -0000

Hi Philip,

> You can load and start the kernel directly from Open
> Firmware since it's an ELF file. However, that only works if the kernel
> resides on a filesystem the Open Firmware implementation understands and
> if you don't need to set any boot flags. Unfortunately, the
> implementation found on Apples computers does not know UFS(2). So a
> different approach (and I think that one is recommended) is to start the
> loader which will be able load the kernel, also from the / filesystem,
> and set boot flags (verbose boot, boot to single user, etc.).

  That's right. Booting the kernel directly from OpenFirmware happens to 
work, mainly because that's the boot path used with gdb/psim. The big 
downside is that there is no metadata, so things like boot flags, the 
root mount, modules, ramdisks and other goodies enabled by the loader 
can't be used.

> So in short: There is no second stage bootloader, only the loader and 
> the kernel. Someone please correct me if I'm wrong.

  Depends on terminology :) If you count OpenFirmware as the first-stage 
bootloader then the FreeBSD loader is a second-stage loader, though it's 
the first in the FreeBSD boot process.

later,

Peter.