getting grub's view of disk geometry from "grub rescue>" prompt?

[Nathan Stratton Treadway]

Question in brief: how can you get Grub, from the "grub recovery>"
prompt, to display its boot-time view of disk drive geometry, etc?


Background: We trying to install Debian Stretch on an old (circa 2004)
system which uses CF cards as the storage medium.  As part of the
upgrade we switched the previous 1GB card to a new 32GB one, and then
proceed to use the Debian Installer CD to install onto the card, with a
single / partition using all the space.

The install appears to complete normally, but when the system is
rebooted grub reports the error message "read or write outside of disk
(hd0)" and then drops to the "grub recovery>" prompt.

(And in fact "ls (hd0,msdos1)/" shows the expected contents of the root
directory, but "ls (hd0,msdos1)/boot" gives that same "outside of disk"
error.)

We figure this error is related grub being unable to access the full
32GB of the device (though the BIOS Setup does report the correct/full
size for the card on the screen showing detected IDE devices).... but I
so far I haven't been able to find any information in the Grub2 manual
or in general web searching explaining how to tell what limits grub is
actually hitting there at boot time.

Can anyone point to a website or previous mailing list thread that
discusses what commands or procedures are available from the grub prompt
to find out grub's internal view of the available devices and
partitions, which mode it is using to access them (i.e. Int13 v.s. LBA),
etc.?

Thanks.

                                                Nathan  


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