4.7 SMP lockup

[Michael Marchetti]

Hi, 
I'm seeing a problem with 4.7 where, very rarely, the system seems to
"lockup". No panic is given. I was able to track it down to all processors
were halted (in the idle loop) since machdep.cpu_idle_hlt=1. The system is a
2 physical XEON procs with hyperthreading enabled. The system was behaving
as though the 8254 system clock was not going off. The only thing I can
think of is some kind of lapic problem where the interrupt is not being
delivered to the CPU. Any others encounter such a problem? thanks, mike.