Date: Sun, 26 Jan 1997 14:14:45 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: joerg_wunsch@uriah.heep.sax.de Cc: freebsd-hackers@freebsd.org Subject: Re: fdisk headache Message-ID: <199701262114.OAA02297@phaeton.artisoft.com> In-Reply-To: <Mutt.19970126104601.j@uriah.heep.sax.de> from "J Wunsch" at Jan 26, 97 10:46:01 am
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> > Boot selectors won't work either. > > Since there's nothing to select from. ;-) > > Right now, there are three reasons to still call it ``dangerously > dedicated'': > > . Since the MBR is identical to the BSD bootstrap, there's no room for > things like `nextboot' after the MBR, and you can't replace the MBR > by fancy things like a boot selector. Hence, in a system that is > not FreeBSD-only, you could at best make drives != #0 ``DD'', and > you won't be able to boot select away from that drive once you > switched there. (Normally, booteasy allows to wander around back > and forth through all the drives.) This is evil. The purpose of the DOS MBR and partition table is to make BIOS happy and to allow multiboot. We don't do ourselves any favors by sabotoging that for other OS's. > The plus side is: [ ... ] > . The number of BIOS geometry constraints to care for reduces drastic- > ally, so you can usually (*) ignore any geometry issues. > > (*) I.e., the BIOS's geometry idea involves at least 15 sectors per > track, 4 heads, and the root file system is not larger than 30 MB. This is a bogus argument based on the assumption that we wouldn't put an absolute sector address in the partition entry like we should so a sector-offset based driver (BSD) could still use the partition table entry without multiplying out C/H/S values. Note that we should put the entry there for our parttition: we should not rely on a DOS tool to do it correctly for us. 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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