anchor.diff:    idle-thread
     wired-stack
     exception-stack
  -  irq-stack)
  +  irq-stack
  +  lapic-timer-active)
   
   (defconstant +ap-trampoline-physical-address+ #x7000
     "Where the AP trampoline should be copied to in physical memory.
  
positive.code:       (cond (time-remaining
               (setf (lapic-reg +lapic-reg-timer-initial-count+)
                     (max 1 (lapic-timer-convert-from-internal-time-units time-remaining)))
               (setf *lapic-timer-active* t))
              (t
               (setf (lapic-reg +lapic-reg-timer-initial-count+) 0)
               (setf *lapic-timer-active* nil)))
        old-remaining)))
  
  (defun preemption-timer-remaining ()
  
negative.code:   (debug-print-line "  timer-current: " (lapic-reg +lapic-reg-timer-current-count+))
    (debug-print-line "  timer-divide: " (lapic-reg +lapic-reg-timer-divide-configuration+)))
  
  (defun lapic-timer-active ()
    ;; Preemption timers are per-CPU...
    (cpu-lapic-timer-active (local-cpu-object)))
  
  (defun preemption-timer-reset (time-remaining)
    "Configure the preemption timer to go off after TIME-REMAINING internal time units.
  