I noticed that if I run ultra2 long enought any reboot command
	(fastboot, fasthalt, reboot) hangs so machine should be power-cycled.
	I don't know how long is 'long enought' because I use machine
	in two limits, whether trace+ddb+no-load or normal under load. 

	I havn't noticed any harm or system degradation. Is there anything
	I can check before issuing reboot. Some directions are needed.

Yes, that is a problem that is known to occur on just about
all sparc64 machines.  The hang happens is that when the OS
terminates and the machine tries to enter the PROM.  It began
after I enabled 64-bit address spaces.  In order to debug the
problem, the machine will need to be issued an XIR and the 
register dumps analyzed.  Most machines require a special
jumper to generate and XIR.  Exx00 and I understand E240,
E250, E420, and E450 machines will generate an XIR if given
a special character sequence on the console.

Eduardo