diff -Naur ocaml-4.00.1/asmrun/natdynlink.c ocaml-4.00.1-data-marsh/asmrun/natdynlink.c
--- ocaml-4.00.1/asmrun/natdynlink.c	2013-03-11 22:23:41.000000000 +0100
+++ ocaml-4.00.1-data-marsh/asmrun/natdynlink.c	2013-03-11 22:24:09.000000000 +0100
@@ -75,7 +75,7 @@
   CAMLparam1 (symbol);
   CAMLlocal1 (result);
   void *sym,*sym2;
-  struct code_fragment * cf;
+  struct code_fragment * cf = NULL;
 
 #define optsym(n) getsym(handle,unit,n)
   char *unit;
@@ -89,11 +89,6 @@
   sym = optsym("");
   if (NULL != sym) caml_register_dyn_global(sym);
 
-  sym = optsym("__data_begin");
-  sym2 = optsym("__data_end");
-  if (NULL != sym && NULL != sym2)
-    caml_page_table_add(In_static_data, sym, sym2);
-
   sym = optsym("__code_begin");
   sym2 = optsym("__code_end");
   if (NULL != sym && NULL != sym2) {
@@ -101,10 +96,23 @@
     cf = caml_stat_alloc(sizeof(struct code_fragment));
     cf->code_start = (char *) sym;
     cf->code_end = (char *) sym2;
+    cf->data_start = NULL;
+    cf->data_end = NULL;
     cf->digest_computed = 0;
-    caml_ext_table_add(&caml_code_fragments_table, cf);
   }
 
+  sym = optsym("__data_begin");
+  sym2 = optsym("__data_end");
+  if (NULL != sym && NULL != sym2) {
+    caml_page_table_add(In_static_data, sym, sym2);
+    if (cf != NULL) {
+      cf->data_start = (char *) sym;
+      cf->data_end = (char *) sym2;
+    }
+  }
+
+  if (cf != NULL) caml_ext_table_add(&caml_code_fragments_table, cf);
+
   entrypoint = optsym("__entry");
   if (NULL != entrypoint) result = caml_callback((value)(&entrypoint), 0);
   else result = Val_unit;
diff -Naur ocaml-4.00.1/asmrun/startup.c ocaml-4.00.1-data-marsh/asmrun/startup.c
--- ocaml-4.00.1/asmrun/startup.c	2013-03-11 22:23:41.000000000 +0100
+++ ocaml-4.00.1-data-marsh/asmrun/startup.c	2013-03-11 22:24:09.000000000 +0100
@@ -59,6 +59,22 @@
                           caml_atom_table, caml_atom_table + 256) != 0)
     caml_fatal_error("Fatal error: not enough memory for the initial page table");
 
+  /* Register the data in the table of code fragments */
+  cf = caml_stat_alloc(sizeof(struct code_fragment));
+  if (caml_data_segments[0].begin != 0) {
+    cf->data_start = caml_data_segments[0].begin;
+    cf->data_end = caml_data_segments[0].end;
+    for (i = 1 ; caml_data_segments[i].begin != 0; i ++) {
+      if (caml_data_segments[i].begin < cf->data_start)
+        cf->data_start = caml_data_segments[i].begin;
+      if (caml_data_segments[i].end > cf->data_end)
+        cf->data_end = caml_data_segments[i].end;
+    }
+  } else {
+    cf->data_start = NULL;
+    cf->data_end = NULL;
+  }
+
   for (i = 0; caml_data_segments[i].begin != 0; i++) {
     /* PR#5509: we must include the zero word at end of data segment,
        because pointers equal to caml_data_segments[i].end are static data. */
@@ -66,6 +82,7 @@
                             caml_data_segments[i].begin,
                             caml_data_segments[i].end + sizeof(value)) != 0)
       caml_fatal_error("Fatal error: not enough memory for the initial page table");
+    
   }
 
   caml_code_area_start = caml_code_segments[0].begin;
@@ -76,8 +93,8 @@
     if (caml_code_segments[i].end > caml_code_area_end)
       caml_code_area_end = caml_code_segments[i].end;
   }
+
   /* Register the code in the table of code fragments */
-  cf = caml_stat_alloc(sizeof(struct code_fragment));
   cf->code_start = caml_code_area_start;
   cf->code_end = caml_code_area_end;
   cf->digest_computed = 0;
diff -Naur ocaml-4.00.1/byterun/extern.c ocaml-4.00.1-data-marsh/byterun/extern.c
--- ocaml-4.00.1/byterun/extern.c	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/extern.c	2013-03-11 22:24:09.000000000 +0100
@@ -24,7 +24,6 @@
 #include "gc.h"
 #include "intext.h"
 #include "io.h"
-#include "md5.h"
 #include "memory.h"
 #include "misc.h"
 #include "mlvalues.h"
@@ -815,10 +814,7 @@
   int i;
   for (i = caml_code_fragments_table.size - 1; i >= 0; i--) {
     struct code_fragment * cf = caml_code_fragments_table.contents[i];
-    if (! cf->digest_computed) {
-      caml_md5_block(cf->digest, cf->code_start, cf->code_end - cf->code_start);
-      cf->digest_computed = 1;
-    }
+    if (!cf->digest_computed) caml_update_code_fragment_digest(cf);
     if (cf->code_start <= addr && addr < cf->code_end) return cf;
   }
   return NULL;
diff -Naur ocaml-4.00.1/byterun/fix_code.c ocaml-4.00.1-data-marsh/byterun/fix_code.c
--- ocaml-4.00.1/byterun/fix_code.c	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/fix_code.c	2013-03-11 22:24:09.000000000 +0100
@@ -25,12 +25,13 @@
 #include "fix_code.h"
 #include "instruct.h"
 #include "intext.h"
-#include "md5.h"
 #include "memory.h"
 #include "misc.h"
 #include "mlvalues.h"
 #include "reverse.h"
 
+char *caml_data;
+asize_t caml_data_size;
 code_t caml_start_code;
 asize_t caml_code_size;
 unsigned char * caml_saved_code;
@@ -44,7 +45,9 @@
   cf = caml_stat_alloc(sizeof(struct code_fragment));
   cf->code_start = (char *) caml_start_code;
   cf->code_end = (char *) caml_start_code + caml_code_size;
-  caml_md5_block(cf->digest, caml_start_code, caml_code_size);
+  cf->data_start = (char *) caml_data;
+  cf->data_end = (char *) caml_data + caml_data_size;
+  caml_update_code_fragment_digest(cf);
   cf->digest_computed = 1;
   caml_ext_table_init(&caml_code_fragments_table, 8);
   caml_ext_table_add(&caml_code_fragments_table, cf);
diff -Naur ocaml-4.00.1/byterun/fix_code.h ocaml-4.00.1-data-marsh/byterun/fix_code.h
--- ocaml-4.00.1/byterun/fix_code.h	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/fix_code.h	2013-03-11 22:24:09.000000000 +0100
@@ -23,6 +23,8 @@
 #include "misc.h"
 #include "mlvalues.h"
 
+extern char *caml_data;
+extern asize_t caml_data_size;
 extern code_t caml_start_code;
 extern asize_t caml_code_size;
 extern unsigned char * caml_saved_code;
diff -Naur ocaml-4.00.1/byterun/intern.c ocaml-4.00.1-data-marsh/byterun/intern.c
--- ocaml-4.00.1/byterun/intern.c	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/intern.c	2013-03-11 22:24:09.000000000 +0100
@@ -26,7 +26,6 @@
 #include "gc.h"
 #include "intext.h"
 #include "io.h"
-#include "md5.h"
 #include "memory.h"
 #include "mlvalues.h"
 #include "misc.h"
@@ -738,10 +737,7 @@
   int i;
   for (i = caml_code_fragments_table.size - 1; i >= 0; i--) {
     struct code_fragment * cf = caml_code_fragments_table.contents[i];
-    if (! cf->digest_computed) {
-      caml_md5_block(cf->digest, cf->code_start, cf->code_end - cf->code_start);
-      cf->digest_computed = 1;
-    }
+    if (!cf->digest_computed) caml_update_code_fragment_digest(cf);
     if (memcmp(digest, cf->digest, 16) == 0) {
       if (cf->code_start + offset < cf->code_end)
         return cf->code_start + offset;
diff -Naur ocaml-4.00.1/byterun/intext.h ocaml-4.00.1-data-marsh/byterun/intext.h
--- ocaml-4.00.1/byterun/intext.h	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/intext.h	2013-03-11 22:24:09.000000000 +0100
@@ -155,12 +155,18 @@
 struct code_fragment {
   char * code_start;
   char * code_end;
+  char * data_start;
+  char * data_end;
   unsigned char digest[16];
   char digest_computed;
 };
 
 struct ext_table caml_code_fragments_table;
 
+/* Defined in misc.c */
+
+extern void caml_update_code_fragment_digest(struct code_fragment *cf);
+
 /* </private> */
 
 #ifdef __cplusplus
diff -Naur ocaml-4.00.1/byterun/meta.c ocaml-4.00.1-data-marsh/byterun/meta.c
--- ocaml-4.00.1/byterun/meta.c	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/meta.c	2013-03-11 22:24:09.000000000 +0100
@@ -67,6 +67,8 @@
   struct code_fragment * cf = caml_stat_alloc(sizeof(struct code_fragment));
   cf->code_start = (char *) prog;
   cf->code_end = (char *) prog + Long_val(len);
+  cf->data_start = NULL;
+  cf->data_end = NULL;
   memcpy(cf->digest, String_val(digest), 16);
   cf->digest_computed = 1;
   caml_ext_table_add(&caml_code_fragments_table, cf);
diff -Naur ocaml-4.00.1/byterun/misc.c ocaml-4.00.1-data-marsh/byterun/misc.c
--- ocaml-4.00.1/byterun/misc.c	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/misc.c	2013-03-11 22:24:09.000000000 +0100
@@ -16,7 +16,9 @@
 #include <stdio.h>
 #include "config.h"
 #include "misc.h"
+#include "intext.h"
 #include "memory.h"
+#include "md5.h"
 
 #ifdef DEBUG
 
@@ -123,3 +125,13 @@
     for (i = 0; i < tbl->size; i++) caml_stat_free(tbl->contents[i]);
   caml_stat_free(tbl->contents);
 }
+
+void caml_update_code_fragment_digest(struct code_fragment *cf) {
+  int i;
+  unsigned char code_digest[16];
+  unsigned char data_digest[16];
+  caml_md5_block(code_digest, cf->code_start, cf->code_end - cf->code_start);
+  caml_md5_block(data_digest, cf->data_start, cf->data_end - cf->data_start);
+  for (i = 0 ; i < 16 ; i ++)
+    cf->digest[i] = code_digest[i] ^ data_digest[i];
+}
diff -Naur ocaml-4.00.1/byterun/startup.c ocaml-4.00.1-data-marsh/byterun/startup.c
--- ocaml-4.00.1/byterun/startup.c	2013-03-11 22:23:36.000000000 +0100
+++ ocaml-4.00.1-data-marsh/byterun/startup.c	2013-03-11 22:24:09.000000000 +0100
@@ -391,8 +391,11 @@
   /* Initialize the debugger, if needed */
   caml_debugger_init();
   /* Load the code */
+  caml_data_size = caml_seek_section(fd, &trail, "DATA");
+  caml_data = read_section(fd, &trail, "DATA");
   caml_code_size = caml_seek_section(fd, &trail, "CODE");
   caml_load_code(fd, caml_code_size);
+  caml_stat_free(caml_data);
   /* Build the table of primitives */
   shared_lib_path = read_section(fd, &trail, "DLPT");
   shared_libs = read_section(fd, &trail, "DLLS");
@@ -477,6 +480,8 @@
   /* Load the code */
   caml_start_code = code;
   caml_code_size = code_size;
+  caml_data = data;
+  caml_data_size = data_size;
   caml_init_code_fragments();
   if (caml_debugger_in_use) {
     int len, i;