Puzzle involving serial console and ...??!?

[Dieter BSD]

> I have determined that whether or not I have a functioning serial
> console for freebeast depends on whether I boot albert from slice
> 1 or slice 2:  if from slice 1, it doesn't work; if from slice 2,
> it does.
>
> Even when the contents of the 2 slices are functionally equivalent
> (that is, the file systems of the 2 slices are as "the same" as a
> "dump 0Lf | restore" pipeline can make them, except for a deliberate
> difference in the contents of /etc/fstab (as the root and /usr file
> systems are on different slices in the two cases)).

You could verify that the 2 slices are *really* the same with
find(1) and cmp(1). (both root and /usr)

You could compare the boot messages in /var/log to see if there are
any differences.

Are there any pesky error messages on the console or in /var/log?

You could try cu(1) instead of tip and see if the same thing happens.

When it doesn't work, what, exactly, happens differently?

Obviously, albert has an intermittent connection, and booting
from a different part of the disk causes different vibrations,
which causes the connection to either short or open.  What's that?
SSD?  Never mind.  :-)