any real documentation of the boot2 prompt?

John Baldwin jhb at
Fri Jan 12 17:16:31 UTC 2007

On Friday 12 January 2007 10:56, Jo Rhett wrote:
> John Baldwin wrote:
> > A BIOS driver number is the number you pass to the BIOS to access a drive.
> > Typically drive 0x0 is a floppy drive and hard drives start at 0x80.
> > Usually the SCSI BIOS will list the BIOS driver number during the POST
> > messages and it will look like 80, 81, etc.  There is no standard way
> > as it is at the BIOS' discretion.
> How do I determine this?  It doesn't list them during boot.

To some extent you are at the mercy of your BIOS writers, yes it sucks, and
this why I like things like EFI and OpenFirmware over BIOS.

> Say I boot off the CD, is there any commands I can use to determine what 
> the BIOS numbers are?  They are da0 and da1 to freebsd.

You can try using 'lsdev' in the loader from the CD.  If a disk is called A:
in the loader printfs it's drive 0, if it's C: it's drive 0x80, D: drive 0x81
(the drive letters may only be mentinoed in the printfs at teh start of the
loader and not in lsdev, can't recall).

> > To answer your question: you need to first make sure your SCSI BIOS is
> > registering your second disk with the BIOS.  Assuming it's mapped as
> > drive 81, you can then use '1:da(1,a)'.  If it shows up as drive 82, then
> > use 2:da(1,a)', etc.
> How does one do so?

It would have to be in your SCSI adapter's BIOS.  They tend to have a BIOS
setup you can enter during boot before the OS loads and you would have to
poke around in there.

John Baldwin

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