From owner-freebsd-hackers Mon Aug 21 23:59:28 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.FreeBSD.org (8.6.11/8.6.6) id XAA08777 for hackers-outgoing; Mon, 21 Aug 1995 23:59:28 -0700 Received: from genesis.atrad.adelaide.edu.au (genesis.atrad.adelaide.edu.au [129.127.96.120]) by freefall.FreeBSD.org (8.6.11/8.6.6) with ESMTP id XAA08747 for ; Mon, 21 Aug 1995 23:59:18 -0700 Received: from msmith@localhost by genesis.atrad.adelaide.edu.au (8.6.9/8.6.9) id RAA26084; Tue, 22 Aug 1995 17:05:10 +0930 From: Michael Smith Message-Id: <199508220735.RAA26084@genesis.atrad.adelaide.edu.au> Subject: Re: Using space in a DOS filesystem To: bde@zeta.org.au (Bruce Evans) Date: Tue, 22 Aug 1995 17:05:10 +0930 (CST) Cc: hackers@freebsd.org In-Reply-To: <199508220645.QAA26716@godzilla.zeta.org.au> from "Bruce Evans" at Aug 22, 95 04:45:06 pm Content-Type: text Content-Length: 1908 Sender: hackers-owner@freebsd.org Precedence: bulk Bruce Evans stands accused of saying: > > >The vn driver is a no-go if we want to boot from this, which is the > >whole idea. Remember, the aim here is to provide a safer way to plonk > >a FreeBSD filesystem onto a disk covered in a FAT filesystem. > > You would need to have the vn device and various tools on the boot > device. This is acceptable for demos and installations, but not so > good for use. But if the slab _is_ the boot device, how do we read the tools from it? > Committing the bogus slice to the partition table looks better than > ever. It allows booting from a normal slice. Anything else has large > bootstrapping problems. Hmm. I'd have hoped that the partition table could be patched after it was read by the kernel, to avoid having to rewrite the MBR every time you booted. (Or at least checking and stuffing the bogus slice back in if something 'smart' had tried to remove it.) I see this scheme falling foul of disk tools, other operating systems and 'smart' virus prevention tools. I can also see it saving the sanity of several kernel hackers. 8) Thinking it through, there's not really a lot that would have to be added in terms of kernel code to support this - a DOS version of the slab-creation code would be needed, and some minor mods to the fbsdboot tool to check the bootslab and stuff the MBR. Anything else? > vn devices can be both sliced and labeled. They just can't be booted from. Ahu - how do you get slices of a vn device? I presume it's just minor-magic? > Bruce -- ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ ]] Genesis Software genesis@atrad.adelaide.edu.au [[ ]] High-speed data acquisition and [[ ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ ]] My car has "demand start" -Terry Lambert UNIX: live FreeBSD or die! [[