Sun3 machines usually need little or no preparation before installing
OpenBSD, other than the usual, well advised precaution of BACKING UP
ALL DATA on any attached storage devices.

You will need to know the SCSI target ID of the drive on which you
will install OpenBSD.  Note that SunOS/sun3 uses confusing names for
the SCSI devices: target 1 is sd2, target 2 is sd4, etc.

It might be a good time to run the diagnostics on your Sun3.  First,
attach a terminal to the "ttya" serial port, then set the "Diag/Norm"
switch to the Diagnostic position, and power-on the machine.  The
Diag. switch setting forces console interaction to occur on ttya.

The console location (ttya, ttyb, or keyboard/display) is controlled
by address 0x1F in the EEPROM, which you can examine and change in
the PROM monitor by entering "q1f" followed by a numeric value (or
just a '.' if you don't want to change it).  Console values are:
	00: default graphics display
	10: tty a (9600-N-8-1)
	11: tty b (1200-N-8-1)
	20: Color option board on P4

OpenBSD will use the EEPROM setting to determine which device to
use as the console, so you should make sure it is correct.
Before you start you might need to consider your disk configuration
to sort out a quirk in SCSI-ID to SD-UNIT mapping that exists on
Sun Sparcstations.

Please note that while OpenBSD and SunOS have a reasonable degree of
compatibility between disk labels and filesystems there are some problems
to watch out for during initial installation or when trying to maintain
both OpenBSD and SunOS environments on the same system.

    If the OpenBSD fsck(8) utility is used on a SunOS filesystem, it will
    set OpenBSD "clean flags" and BSD4.4 summary fields in the superblock.
    SunOS does *not* like this and you will have to do a "fsck -b 32" under
    SunOS to access an alternate superblock to repair the filesystem.  You
    should always specify SunOS filesystem with a "pass number" of 0 in
    their /etc/fstab entry to prevent this, and preferably mount them "RO".

    If SunOS fsck is used on an OpenBSD filesystem in the default OpenBSD
    (4.4BSD) format, it will first complain about the superblock and then
    about missing . and .. entries.  Do *not* try to "correct" these
    problems, as attempting to do so will completely trash the filesystem.

    You should avoid using the new OpenBSD "-s enable" option to the 
    "tunefs" command, which enable the soft update feature.  
    Although untested, it is likely that SunOS would be confused by a 
    filesystem with soft update flags enabled.

OpenBSD supports both OpenBSD "native" disklabels and "Sun compatible"
disklabels.  Unless you have some really good reason, you should stick
with the Sun compatible labels.  The disklabel(8) "-r" switch says to
use OpenBSD labels, which is a bit counter-intuitive and contrary to
the reasons why might want to use "-r" on other OpenBSD ports.

Don't use "-r" with disklabel(8).


The OpenBSD "Sun Compatible" disklabel have been extended to support 16
partitions, which may be compatible with Solaris, but the old SunOS
format(8) utility only sees the first 8 partititions and may "lose"
information about the extended partitions.

Use SunOS format(8) only with *extreme* caution on drives that contain
OpenBSD partitions.


OpenBSD and Sun BSD bootblocks are similar in concept, though implemented
differently.  The OpenBSD bootblocks are architecture independent and also
understand the extended disklabels with 16 partitions.  You can use SunOS
bootblocks, but remember that OpenBSD bootblocks must be installed with
OpenBSD installboot and SunOS bootblocks with SunOS installboot.