Adding a new linux partition is a multi-step process...

1. Use pdisk (or other partitioning utility) to create the new
partition as a free unix block. This can be done under Mac O/S or
Mklinux.
2. As root in Mklinux, create a mount point. For example, if you want
to mount the new partition at /data, then "mkdir /data".
3. As root, make the file system using "mkfs -c -t ext2 /dev/sdxx",
where sdxx is the physical loation of new partition and ext2 is the file
system type. This will create the superblock that fsck complained about.
The process should take a couple of minutes, because the -c option scans
the new partition of for anomolies.

2a.  (4/25/97 fadushin@top.cis.syr.edu)  I had to use mke2fs without the
-t ext2 option under linux-pmac to build an extra linux parition.  mkfs reported
an error to mkfs.minix.

4. just to check and see if things worked, do a "mount -nrw /dev/sdxx
/data" as root to check if the file system will mount properly. If this
works, then go to 5.
5. Make an entry into the /etc/fstab file analagous to the entries that
are already there. This should be fairly obvious, because you must
already have at least two entries, one for your / partition and another
for /usr.
6. reboot. This may take longer than normal, as fsck will do a thorough
job at checking the new partition.

yengst@photon.com