Sun computers use a boot monitor program called “OpenBoot”. From the boot monitor we can perform certain hardware tests, issue boot instructions, and set many parameters stored in nonvolatile RAM on the CPU board. Some of these setting must be adjusted for particular situations.
Full documentation is available at:
Getting to the boot monitor
The best way is to cause an orderly system shutdown with
one of these commands, shown in order of preference:
shutdown -yi 0
If this is not possible then it can be forced by:
From the tty console send a RS-232 BREAK signal.
(serial consoles default to 9600,8,N,1)
From a Sun Framebuffer/keyboard press the STOP key
and the ‘a’ key at the same time.
In general this method is BAD and has the same risks to
the file system as just turning off the power.
If you accidently sends a break or STOP-a, you can safely
return to the running OS state with this command:
If you issue ANY other commands first then go may not work.
Restore default NVRAM settings
Set boot device
ok> setenv boot-device disk
Other options include:
disk0 main SCSI controller target 0
disk1 main SCSI controller target 1
disk2 main SCSI controller target 2
disk3 main SCSI controller target 3
disk is same as disk3
[if disk is not main SCSI controller ]
ok> nvalias disk /sbus@1,f8000000/dma@3,81000/esp@3,80000/sd@3,0
System may take 30 seconds during POST to show any response.