Re: "grub" command works, but GRUB boot loader hangs

[Ben Liblit]

In my original problem report, I described my machine's hardware
setup.  This is an old machine, so it's pretty cluttered in there.
Like a good scientist, I decided to start unplugging things and see if
there is one particular piece of hardware that is causing the problem.

Recall that this system has a SCSI controller with two drives, one of
which is ordinarily used as the boot drive.  There's also an old IDE
drive hanging off the secondary channel, a SCSI CD-ROM, and a floppy
tape drive controller.  (For more complete details, see
<http://mail.gnu.org/pipermail/bug-grub/2001-August/005353.html> for
my original message, or 
<http://mail.gnu.org/pipermail/bug-grub/2001-August/005360.html> for a
shorter configuration summary produced by "fdisk -l".)

Recall as well that under normal use, with everything plugged in, GRUB
detects (fd0), (fd1), (hd0), and (hd1).  That's one floppy drive too
many, as I have only one.  It's also one hard drive too few, as I have
three.  The "geometry (fd0)" command produces error messages 18 and
22, while the "geometry (fd1)" command produces error message 25.
Using "geometry" or any other nontrivial command on (hd0) or (hd1)
hangs the system.

First off, the floppy tape drive controller is not relevant.  I can
remove the card and nothing changes.  I thought that perhaps this
controller was causing the extra "(fd1)" floppy drive to be detected,
but apparently that's not where it's coming from.

Unplugging the SCSI CD-ROM drive also has no effect.

Unplugging the secondary master IDE hard drive has no effect.  This is
surprising, because when GRUB is working correctly it should detect
this drive and make it available.

Unplugging either one of the two SCSI hard drives removes (hd1).
Accessing (fd0) or (fd1) yields the same errors as before, and (hd0)
still hangs.  Unplugging both SCSI hard drives removes both (hd0) and
(hd1).

Removing the SCSI controller card itself removes both (hd0) and
(hd1).  The two floppy devices are still present, and still yield the
same errors as before.

So this leaves me with some specific questions:

   - Why does (fd0) yield errors, and why is an extra floppy device
     being detected as (fd1)?  Note that this remains constant no
     matter how much hardware I unplug or remove.

   - Why is the secondary master IDE hard drive not detected?

   - Why do the two SCSI hard drives, which are detected as (hd0) and
     (hd1), hang GRUB on any nontrivial effort to use them?

   - Why is there an eleven second hang when GRUB first tries to
     detect my hardware?