[Gllug] mount ancient SGI CDs on current Ubuntu

[Richard Cottrill]

Hi People,

I'm messing about with an old SGI Octane I have in my nerd cupboard
and trying to bring it into the land of the living. Right now I don't
particularly care what OS it runs, but I have some Irix CDs, and they
seem like a good start (Linux support for Octane might force me into
using Gentoo, and life's too short for that).

Unfortunately, Linux kernel doesn't support the SGI disk labelling
scheme (man fdisk - could be out of date), but I've found a workaround
for that ( http://www.geraldthewes.info/pd-2lf-d100onlinux2.6.xhtml ),
but I can't get it to work.

I get:
richard at bletch:~$ fdisk -l -u /dev/scd0
Note: sector size is 2048 (not 512)

Disk /dev/scd0 (SGI disk label): 255 heads, 63 sectors, 13 cylinders
Units = sectors of 1 * 2048 bytes

----- partitions -----
Pt#     Device  Info     Start       End   Sectors  Id  System
 8: /dev/scd0p1           47776    868935    821160   5  SGI sysv
 9: /dev/scd0p2               0     47775     47776   0  SGI volhdr
11: /dev/scd0p3               0    868959    868960   6  SGI volume
----- Bootinfo -----
Bootfile:
----- Directory Entries -----
 0: sgilabel   sector   32 size     512
 1: mr         sector   33 size18688000
 2: sash64     sector36533 size  281656
 3: sashARCS   sector37084 size  341332

This suggests to me I need to use an huge offset of (2048 [sector
size] * 47776 [starting sector of sysv disk partition]) 97845248. So I
use this unwieldy number thus:

richard at bletch:~$ sudo losetup -o 97845248 -r /dev/loop0 /dev/scd0

and now mount:

richard at bletch:~$ sudo mount -o ro -t sysv /dev/loop0 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

dmesg says something is bust:

[422121.924000] VFS: unable to find oldfs superblock on device loop0

Any ideas on how to read this CD?

Thanks,

Richard
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