- oc->image = mmap(map_addr, n, PROT_EXEC|PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+
+ /* Link objects into the lower 2Gb on x86_64. GHC assumes the
+ * small memory model on this architecture (see gcc docs,
+ * -mcmodel=small).
+ */
+#ifdef x86_64_HOST_ARCH
+#define EXTRA_MAP_FLAGS MAP_32BIT
+#else
+#define EXTRA_MAP_FLAGS 0
+#endif
+
+ oc->image = mmap(map_addr, n, PROT_EXEC|PROT_READ|PROT_WRITE,
+ MAP_PRIVATE|EXTRA_MAP_FLAGS, fd, 0);