anchor.diff:  (defun address-l3-bits (address) (ldb (byte 9 30) address))
   (defun address-l2-bits (address) (ldb (byte 9 21) address))
   (defun address-l1-bits (address) (ldb (byte 9 12) address))
  +
  +(declaim (inline zeroize-page))
  +(defun zeroize-page (addr)
  +  (dotimes (i 512)
  +    (setf (sys.int::memref-unsigned-byte-64 addr i) 0)))
   
   (defun detect-paging-disk ()
     (dolist (disk (all-disks))
  
positive.code:        (let* ((frame (or (allocate-physical-pages 1)
                           (panic "Aiee. No memory.")))
                (cache-addr (+ +physical-map-base+ (ash frame 12))))
           (dotimes (i 512)
             (setf (sys.int::memref-unsigned-byte-64 cache-addr i) 0))
           (setf (sys.int::memref-t cache-addr 511) *block-cache*
                 *block-cache* cache-addr)
           (setf (sys.int::memref-unsigned-byte-64 cache-addr 0) block-id
  
negative.code:         (let* ((frame (or (allocate-physical-pages 1)
                            (panic "Aiee. No memory.")))
                 (addr (+ +physical-map-base+ (ash frame 12))))
            (zeroize-page addr)
            (setf (page-table-entry page-table index) (logior (ash frame 12)
                                                              +page-table-present+
                                                              +page-table-write+))
  