From owner-freebsd-hackers@FreeBSD.ORG Wed Jun 17 12:09:13 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3B3B2106564A for ; Wed, 17 Jun 2009 12:09:13 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-qy0-f173.google.com (mail-qy0-f173.google.com [209.85.221.173]) by mx1.freebsd.org (Postfix) with ESMTP id E6F7D8FC14 for ; Wed, 17 Jun 2009 12:09:12 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: by qyk3 with SMTP id 3so314851qyk.3 for ; Wed, 17 Jun 2009 05:09:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to:cc :content-type:content-transfer-encoding; bh=K3VcIs5hsDAK4sSyoQt1650ZbVFng7keApkiXAzbQtA=; b=WYs+TwVje/Y79klHAyvJeVzBXzquw8xqXCUeyJrsNssvDrWlka2Ym/wn5T3x6xeYsf r5kHyrlGizwKh/3FkxI/pvQd+tVMHZ+ez2wzOhqHm4e4BGimJ0kGvqfcyL3m3p6mmoWF imUYXfCHYRRM5C+YuPAYmd8nxLSsJCocfRi3I= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=ErkYH7Lq/bmeeYP54TNDMBbycY4N8331xEyBZmNlb4otHNY6nCjEp7nmgxYHSx3QpM e2Tp1K/jlX6Tncc67mJvym8fXS3GhuXZyQVVprprYWlBH9VicpjMjDT3SuRcO1TFMsV1 WV5DTFEuS5hKZOcmmM92V7An8DxsmZK70QS98= MIME-Version: 1.0 Sender: adrian.chadd@gmail.com Received: by 10.229.81.198 with SMTP id y6mr7628qck.106.1245240552405; Wed, 17 Jun 2009 05:09:12 -0700 (PDT) In-Reply-To: <20090616172306.GA91395@keira.kiwi-computer.com> References: <200906162350.40221.doconnor@gsoft.com.au> <20090616172306.GA91395@keira.kiwi-computer.com> Date: Wed, 17 Jun 2009 20:09:12 +0800 X-Google-Sender-Auth: 1c40c6d6e21f2604 Message-ID: From: Adrian Chadd To: rick-freebsd2008@kiwi-computer.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: freebsd-hackers@freebsd.org Subject: Re: Loader reading FAT X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Jun 2009 12:09:13 -0000 2009/6/17 Rick C. Petty : > I read somewhere that there isn't enough space in the boot2 loader to put > such logic. =A0You're only guaranteed 15 512-byte sectors or 7680 bytes, = if > you use any UFS partition. =A0It's pretty tight; I think you will find it > difficult to insert another file system in there, especially one as > complicated as msdos. =A0libstand is 223 KB, so it's not as trivial as yo= u > think. > > Theoretically it would be possible: for example, if you're willing to set > aside a separate partition you would have as much room as you want. =A0Or= if > you put it at the front of a UFS partition, you have just under 256 KB of > room since our UFS code will search for the superblock at a byte offset o= f > 262144, but there aren't any knobs to newfs so you'd have to hack it > together. =A0Take a look at /usr/src/sys/boot/i386/boot2/ for starters. This is why I pointed out the NetBSD DOS bootloader stuff. In effect, you could "just" boot a FreeBSD install by teaching the NetBSD bootloader and loader(8) enough about each other to initialise loader; loader then has much more memory to play with understanding multiple filesystems and slicing/labelling methods. Boot0, boot1, boot2 wouldn't even be involved. Adrian