primary superblock features???

[Tom Horsley]

A while back I mentioned this nonsense (but never got
a response):

>On two different fedora 8 systems (which happen to have other boot partitions
>as well to different linux distros), I have rebooted recently and gotten
>fsck problems on reboot to fedora 8 with the message:
>
>primary superblock features different from backup, check forced.

I just now rebooted one of the systems that got this error
on a previous reboot, and this time the kernel crashed
with something about "kernel math error" near the top of the
screen, various routines with "superblock" in their name
in the middle of the backtrace, and "unmount" near the bottom
of the screen.

Just for curiosity, I rebooted again (after having fsck fix an
orphan inode apparently leftover from the crash), and it didn't
happen the 2nd time.

I really am curious what the heck is going on with these superblocks
(they don't seem all that super to me :-).