4/28  Is it safe to rlogin/ssh to a FreeBSD computer and do a "make
      installworld" to upgrade?  Or must this be done in single user
      mode with the computer off the net? I have a rackmount machine
      to upgrade.  I am trying to avoid putting console on it.
        \_ It's doable, but you should:
           1. double check that mergemaster will bring up sshd
           2. make sure your enet driver works and is installed correctly
           3. be on location for the reboot, just in case.
        \_ Do you have another machine with a free serial port? If so,
           I would enable serial console on the machine you want to
           upgrade, and then connect to it on serial console using
           minicom (or whatever) from the other machine. This way you
           can bring the system down to single user, do the upgrade and
           debug the result without a console.