anchor.diff:       #'dx-lambda))
   
   (defun call-with-world-stopped (fn)
  -  (funcall fn))
  +  ;; Globally bind it, allow for recursive stoppage.
  +  (let ((prev *world-stopper*))
  +    (assert (or (not prev) (eql prev (current-thread))))
  +    (unwind-protect
  +         (progn
  +           (setf *world-stopper* (current-thread))
  +           (funcall fn))
  +      (setf *world-stopper* prev))))
   
   (defmacro with-world-stopped (&body body)
     `(call-with-world-stopped (dx-lambda () ,@body)))
  
positive.code:   "This lock protects the special variables that make up the thread list and run queues.")
  (defvar *thread-run-queue-head*)
  (defvar *thread-run-queue-tail*)
  
  ;; FIXME: There must be one idle thread per cpu.
  ;; The cold-generator creates an idle thread for the BSP.
  
negative.code: (defun initialize-initial-thread ()
    "Called very early after boot to reset the initial thread."
    (let* ((thread (current-thread)))
      (setf *world-stopper* thread)
      (setf (thread-state thread) :active)))
  
  (defun finish-initial-thread ()
  