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To: "Jordan K. Hubbard" <jkh@time.cdrom.com>
Cc: current@freefall.freebsd.org
Subject: Re: 2.2-ALPHA install failure 
Reply-To: darrylo@sr.hp.com
In-Reply-To: Your message of "Sat, 23 Nov 1996 21:55:50 PST."
Date: Sun, 24 Nov 1996 10:53:50 -0800
From: Darryl Okahata <darrylo@hpnmhjw.sr.hp.com>
Sender: owner-current@FreeBSD.ORG
X-Loop: FreeBSD.org
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> > Humm... let me see... if I get this right (I don't use sysinstall, but
> > I have seen this X/1/1 translation thing it does) sysinstall defaults to
> > a X/1/1 translation, and even goes so far as to write that into the
> > MBR on a ``dangerously dedicated'' install.
> 
> This was what phk recommended as proper "hint" values for libdisk in
> the dangerously-dedicated case.  What would you suggest instead?

     How about the values of "historical_bogus_partition_table", as
given in sys/i386/isa/diskslice_machdep.c?

	The data for partition 3 is: 
	sysid 165,(FreeBSD/NetBSD/386BSD) 
	    start 0, size 50000 (24 Meg), flag 80 
	       beg: cyl 0/ sector 1/ head 0; 
	       end: cyl 1023/ sector 63/ head 255 

These are the "dedicated disk" values installed by disklabel
(indirectly, via the first-stage boot, "/usr/mdec/boot1").

     For dedicated disks (that is, for true dedicated-disks that use the
historical_bogus_partition_table), the first-stage boot uses only the
beginning sector address (0/1/0).  The second-stage boot uses only the
start offset ("start 0", in the above).  The slice size ("50000") and
the end cylinder address are ignored.  Both of these boots obtain the
disk geometry from the BIOS (BIOS int 0x13, function 0x8).  (Hopefully,
the BIOS returns the correct values.)  For more information, see the
following files in sys/i386/boot/biosboot:

	boot.c
	disk.c
	bios.S

[ Side note: I'm coming into the middle of this conversation.  Is there
  any way we can make the mailing list archives browsable?   Being
  searchable isn't enough.  ]

     -- Darryl Okahata
	Internet: darrylo@sr.hp.com

DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion, or policy of Hewlett-Packard, or of the
little green men that have been following him all day.