[Sbcl-help] mmap on 64 bit sbcl

[Andras S. <as...@ma...>]

Following Juho Snellman's nicely commented example on
http://paste.lisp.org/display/27891 I tried to write out/mmap in
arrays on both 32 and 64 bit sbcl (both on Linux). It went
smoothly on x86, but on x86_64 I get the following:

(require 'sb-posix)

(defvar *a*)

(defun create-lisp-mem-from-array (array file)
  (declare (optimize (speed 1)))
  (with-open-file (map-file file
                            :direction :output
                            :if-exists :supersede
                            :element-type '(unsigned-byte 64))
    ;; Header
    (write-byte sb-vm::simple-array-unsigned-byte-60-widetag map-file)
    ;; Array size placeholder
    (write-byte 8 map-file)
    (loop for in across array
          with count = 0
          do
          (let ((data (ash in sb-vm::n-fixnum-tag-bits)))
            (incf count)
            (write-byte data map-file))
          finally
          (file-position map-file 1)
          (write-byte (ash count sb-vm:n-fixnum-tag-bits)
                      map-file))))


(defun load-lisp-mem (map-file variable)
  (with-open-file (file map-file)
    (let* ((sap (sb-posix:mmap nil
                               (file-length file)
                               sb-posix:prot-read
                               sb-posix:map-private
                               (sb-impl::fd-stream-fd file)
                               0))
           (addr (logior (sb-sys:sap-int sap)
                         sb-vm:other-pointer-lowtag)))
      (setf (symbol-value variable) (sb-kernel:make-lisp-obj addr))
            (values))))


CL-USER> (create-lisp-mem-from-array #(9 8 7 6) "map")
NIL
CL-USER> (load-lisp-mem "map" '*a*)
; No value
CL-USER> (typep *a* 'array)
NIL

and the value of *a* is garbage.

$ od map 
0000000 000000 000000 000000 133000 000000 000000 000000 020000
0000020 000000 000000 000000 044000 000000 000000 000000 040000
0000040 000000 000000 000000 034000 000000 000000 000000 030000
0000060

(sbcl is 0.9.17 binary downloaded from sf.)

What am I missing?

Andras