anchor.diff:  
   (defun generic-timer-irq-handler (interrupt-frame irq)
     (declare (ignore irq))
  -  (setf (%cntp-tval) *generic-timer-reset-value*)
  +  (setf (%cntv-tval) *generic-timer-reset-value*)
     (beat-heartbeat *run-time-advance*)
     (profile-sample interrupt-frame)
     :completed)
  
positive.code:   (mezzano.lap.arm64:msr :cntp-ctl-el0 :x9)
    (mezzano.lap.arm64:ret))
  
  (sys.int::defglobal *generic-timer-rate*)
  (sys.int::defglobal *generic-timer-reset-value*)
  (sys.int::defglobal *run-time-advance*)
  
negative.code:                 fdt-node
                  :exclusive t)
      ;; Set countdown value.
      ;; ### why is this 0 and not *generic-timer-reset-value*?
      (setf (%cntv-tval) 0)
      (%isb)
      ;; Enable the timer.
      (setf (%cntv-ctl) 1)
      (%isb)))
  
  (defun get-universal-time ()
    (+ *rtc-adjust* (truncate (%cntvct) *generic-timer-rate*)))
  
  (defun sys.int::tsc ()
    ;; This isn't the cycle counter, but it's close enough for now.
    (prog1
        (%cntvct)
      (%isb)))
  
  (defun get-high-precision-timer ()
    ;; TODO
    (prog1
        (%cntvct)
      (%isb)))
  
  (defun high-precision-time-units-to-internal-time-units (hp-time)
  