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Date:      Sat, 26 Jan 2002 13:12:25 -0700
From:      Ian <freebsd@damnhippie.dyndns.org>
To:        Dragon Fire <dragonfire820@mediaone.net>, <freebsd-hackers@freebsd.org>
Subject:   Re: Emergency Help Needed
Message-ID:  <B8785BB9.96BD%freebsd@damnhippie.dyndns.org>
In-Reply-To: <008b01c1a6a0$a2942300$6401a8c0@gandalf>

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> Hi Folks,
> 
> I have an emergency and I need some quick help.
> 
> I just ran boot0cfg to install boot0 as my boot code instead of the standard
> mbr. This is on a dedicated FreeBSD system. Now the system boots and gives
> me a choice F4 FreeBSD or F5 Disk 1 both selections hang. I had numerous
> problems getting 4.4 to boot from the hard disk in the first place because
> of BIOS disk settings.

I've had a lot of trouble with the mbr since FreeBSD 4.0.  The trouble I
usually run into is when I stick a new scsi drive into a system which is
unformatted or has who-knows-what on it (like it was formerly in a Mac).
The adaptec card adds it as "bios drive 1" and then the mbr on drive 0
detects it and gives me choices of F1 or F5, the latter being the new drive.
Even if I hit F1 or let it choose that by default, the btx loader crashes.
If I reboot and use the adaptec bios settings to exclude the new drive from
the bios drive set, then I can boot off the existing drive and properly
fdisk and disklabel the new drive so it can be added back to the bios list
for the next reboot.

It acts very much like the presence of garbage in the mbr of the new drive
causes the btx loader stuff to fail.  It's been a long time since I've
messed with mbr stuff (like, the MSDOS 3.3 days), but I vaguely remember
that there's supposed to be a checksum there or something to indicate
whether the data and/or loader code is valid.

Anyway, I don't know if any of this is appropriate to your situation, just
thought I'd mention that in my experience the boot process can get screwed
up by data on a drive you're NOT booting from, which is way counter-
intuitive to me.  If you can exclude other drives from the bios drive list
with your bios or scsi-card settings, that might help.

-- Ian


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