anchor.diff:  (defun quiesce-cpus-for-world-stop ()
     ;; Bring all CPUs to a consistent state to stop the world.
     (setf *non-quiescent-cpus-remaining* (1- *n-up-cpus*))
  -  (broadcast-ipi +quiesce-ipi-vector+)
  +  (broadcast-ipi +ipi-type-fixed+ +quiesce-ipi-vector+)
     (loop
        (when (eql *non-quiescent-cpus-remaining* 0)
          (return))
  
positive.code:   (maybe-preempt-via-interrupt interrupt-frame))
  
  (defun broadcast-panic-ipi ()
    (broadcast-ipi +panic-ipi-vector+))
  
  (defun panic-ipi-handler (interrupt-frame info)
    (declare (ignore interrupt-frame info))
  
negative.code:                                                               (ash type 8)
                                                                vector)))
  
  (defun broadcast-ipi (type vector &optional including-self)
    (dolist (cpu *cpus*)
      (when (and (eql (cpu-state cpu) :online)
                 (or including-self
                     (not (eql cpu (local-cpu-object)))))
        (send-ipi (cpu-apic-id cpu) type vector))))
  
  (defun broadcast-wakeup-ipi ()
    (broadcast-ipi +ipi-type-fixed+ +wakeup-ipi-vector+))
  
  (defun wakeup-ipi-handler (interrupt-frame info)
    (declare (ignore info))
  