Date: Mon, 30 Oct 2000 18:19:18 +0200 (SAST) From: Robert Nordier <rnordier@nordier.com> To: obrien@FreeBSD.ORG (David O'Brien) Cc: dillon@earth.backplane.com (Matt Dillon), tlambert@primenet.com (Terry Lambert), freebsd-stable@FreeBSD.ORG (freebsd-stable@FreeBSD.ORG), hackers@FreeBSD.ORG Subject: Re: Really odd "BTX halted" problem booting FreeBSD on VALinux hardware Message-ID: <200010301619.SAA53310@siri.nordier.com> In-Reply-To: <20001030055307.B41250@dragon.nuxi.com> from "David O'Brien" at Oct 30, 2000 05:53:07 AM
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David O'Brien wrote:
> On Fri, Oct 27, 2000 at 01:10:56PM +0200, Robert Nordier wrote:
> > Just doing the disklabel -w -r followed by the disklabel -B is creating
> > a dangerously dedicated disk,
>
> Actually this is a "fully dedicated" disk. (made to look like a 50MB or
> so disk to M$ products)
> Sysinstall is used to create a "dangeriously dedicated" disk (when not
> create slices.
I can't say I agree with the distinction (though I'm not sure it
really matters).
Consider this comment in sys/i386/i386/autoconf.c:
| * For properly dangerously dedicated disks (ones with a historical
| * bogus partition table), the boot blocks will give slice = 4, but
| * the kernel will only provide the compatibility slice since it
| * knows that slice 4 is not a real slice. [....]
The "historical bogus partition table" is defined in the file
sys/kern/subr_diskmbr.c as follows:
| static struct dos_partition historical_bogus_partition_table[NDOSPART] = {
| { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
| { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
| { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
| { 0x80, 0, 1, 0, DOSPTYP_386BSD, 255, 255, 255, 0, 50000, },
| };
and this is the same table entry that appears in the hexdump provided
by Matt Dillon:
| Raw data on disk after 'disklabel -w -r da0 auto; disklabel -B da0 auto'
|
| 000000f0 66 8b 46 08 52 66 0f b6 d9 66 31 d2 66 f7 f3 88 |f.F.Rf...f1.f...|
| . . . . .
| 000001e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 80 00 |................|
| 000001f0 01 00 a5 ff ff ff 00 00 00 00 50 c3 00 00 55 aa |..........P...U.|
It's a long time since I used sysinstall, but I assume that a "fully
dedicated disk" just has a normal partition table with a single entry
that allocates all available space.
The above, OTOH, is an illegal fdisk partition table entry, and what
I think most of us would refer to as "dangerously dedicated".
--
Robert Nordier
rnordier@nordier.com
rnordier@FreeBSD.org
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