Sun V100 error: Fast Data Access MMU Miss

This post is an alternative method to: http://netmgt.blogspot.com/2010/04/your-sun-v100-openbootprom-cant-find.html

After replacing or removing the CD/DVD-ROM on a Sun V100, it's likely you'll get an odd/annoying boot sequence error:

Fast Data Access MMU Miss

You'll need to access the OpenBOOT PROM (OBP) to resolve this issue. Usually the easiest way is:

# sync; sync; init 0 (if you're able to do this, go to the bottom of post for OBP commands to resolve the MMU error)

Lacking the ability to reach a normal command line, ensure you are connected to the server's LOM (Lights Out Management) port with a console cable, and use the LOM break key-sequence, an octothorpe followed by a period at any time:

#.

lom>

This will immediately drop you into the LOM level. (If the screen is blank after the break sequence, press the enter key and the LOM prompt should appear.) LOM is a low level system; the higher level OS is still running and must be shut down:

lom> poweroff

We'll now temporarily alter the boot sequence:

lom> bootmode forth

We're now ready to boot into the OBP:

lom> poweron

You're at the OBP (OpenBOOT was Sun's version of the FORTH operating system thus the odd bootmode command) famous for its OK prompt and postfix aka Reverse Polish Notation (RPN) of equations. If you're ever in doubt whether you're using FORTH or that it's functioning correctly, type:

ok 3 2 + .

and it will return:

5

ok

You're ready to correct the problematic setting:

ok setenv auto-boot? false

Reboot:

ok reset-all

The new setting is saved and subsequent boots will not have a Fast Data Access MMU Miss error.