Date: Tue, 16 Feb 1999 09:56:29 -0800 From: Charles Henrich <henrich@flnet.com> To: freebsd-questions@freebsd.org Subject: 3.1 Trouble.txt ? Message-ID: <19990216095628.21912@orbit.flnet.com>
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Does anyone have an update for this section of trouble.txt for the 3.1 Boot?
Q: What is this 'bios_drive:interface(unit,partition)kernel_name' thing
that is displayed with the boot help?
A: There is a longstanding problem in the case where the boot disk is
not the first disk in the system. The BIOS uses a different numbering
scheme to FreeBSD, and working out which numbers correspond to which
is difficult to get right.
In the case where the boot disk is not the first disk in the system,
FreeBSD can need some help finding it. There are two common situations
here, and in both of these cases, you need to tell FreeBSD where the
root filesystem is. You do this by specifying the BIOS disk number,
the disk type and the FreeBSD disk number for that type.
The first situation is where you have two IDE disks, each configured as
the master on their respective IDE busses, and wish to boot FreeBSD from
the second disk. The BIOS sees these as disk 0 and disk 1, while
FreeBSD sees them as wd0 and wd2.
FreeBSD is on BIOS disk 1, of type 'wd' and the FreeBSD disk number
is 2, so you would say:
1:wd(2,a)kernel
Note that if you have a slave on the primary bus, the above is not
necessary (and is effectively wrong).
The second situation involves booting from a SCSI disk when you have
one or more IDE disks in the system. In this case, the FreeBSD disk
number is lower than the BIOS disk number. If you have two IDE disks
as well as the SCSI disk, the SCSI disk is BIOS disk 2, type 'da' and
FreeBSD disk number 0, so you would say:
2:da(0,a)kernel
To tell FreeBSD that you want to boot from BIOS disk 2, which is
the first SCSI disk in the system. If you only had one IDE disk,
you would use '1:' instead.
Once you have determined the correct values to use, you can put the
command exactly as you would have typed it in the /boot.config file
using a standard text editor.
Unless instructed otherwise, FreeBSD will use the contents of this
file as the default response to the 'boot:' prompt.
-Crh
Charles Henrich Manex Visual Effects henrich@flnet.com
http://orbit.flnet.com/~henrich
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