The system prints the following warning message while booting:
SunOS Release 5.5.1 Version Generic_103640-03 [UNIX(R) System V Release 4.0] Copyright (c) 1983-1996, Sun Microsystems, Inc. WARNING: add_spec: No major number for sf
If no SENA is attached to the system, the message can be safely ignored. To stop seeing the message, comment out the last line in /kernel/drv/ssd.conf that references sf(7D).
If you do this, and then later attach a SENA to your system, remember to uncomment this line again.