Date: Tue, 31 Oct 1995 20:46:19 +1700 (MST) From: Terry Lambert <terry@lambert.org> To: msmith@atrad.adelaide.edu.au (Michael Smith) Cc: joerg_wunsch@uriah.heep.sax.de, freebsd-hackers@FreeBSD.org Subject: Re: boot disk.... Message-ID: <199511010346.UAA11220@phaeton.artisoft.com> In-Reply-To: <199511010113.LAA05097@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Nov 1, 95 11:43:06 am
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> > > Nothing wrong with this. I had infact even considered a scenario where > > > the bootstrap, if it didn't find a BSD slice where it thought one should > > > be, would search the disk looking for it, and (if possible?) make whatever > > > corrections might be in order. > > > > I hope you won't break the ability to boot right off sector 0, do you? > > That's what an MBR does. If you mean, have a disk without a sector 0 > DOS-style partition table; I would say that booting from it should be a big > no-no. > > If I understand Terry correctly, the DOS-style MBR is an Open Boot > requirement anyway; you lose one track of the disk to using this > scheme - is this a major problem? Actually it is a requirement. So is a FORTH interpreter that can be called from protected mode to do disk, net, and console I/O before you have drivers for the local device ...going to write one that uses VM86() for us? 8-). I think it is necessary to support "naked" devices -- devices without one or more layers of partitioning and/or media perfection (what NT erroneously calls 'FtDISK' for "Fault Tolerance"). A Naked device (BSD disklabel alone) buys you independence from geometry. At least that way, in every case but non-linear partitioning, you can always use the disk for BSD. Non-linear partitioning (like BIOS-based bad sector sparing) will screw you every time. The best you can hope for is that it will work for most of the "naked" cases because uf to some 'N', sector 0..N will be the same with or without the translation in place. This leaves a "BSD only drive" for some people who can't use BSD at all otherwise, which is the current state of affairs. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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