anchor.diff:    "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*)
  +
  +(defvar *world-stopper*)
   
   ;; FIXME: There must be one idle thread per cpu.
   ;; The cold-generator creates an idle thread for the BSP.
  
positive.code:   (setf (sys.int::%array-like-ref-t thread +thread-lock+) :unlocked))
  
  (defun push-run-queue (thread)
    (cond ((null *thread-run-queue-head*)
           (setf *thread-run-queue-head* thread
                 *thread-run-queue-tail* thread)
  
negative.code:              (t ;; Wait for an interrupt.
                (sys.int::%stihlt))))))
  
  (sys.int::define-lap-function %%simple-thread-entry-trampoline ()
    (:gc :no-frame :layout #*1)
    ;; The regular stack contains the function to call.
    (sys.lap-x86:pop :rbx)
  