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.


this is a 'known problem.'  my U5 will hang if i boot it, build a
kernel from scratch, and try to reboot it.  it _isn't_ swap related
because my ultra's don't swap.  it happens when entering the prom,
and isn't restricted to shutdown.  eg, a `mach prom' from ddb will
hang if the machine has been sufficiently active.  it *definately*
seems to be triggered by activity... if my U5 sits idle for several
days, doing nothing, it reboots fine.  my U1 which never normally
reboots, and is typically very active, _always_ hangs at rebot time.


it is very annoying.


.mrg.