--- src/backend/port/sysv_shmem.c.orig	2014-07-01 21:22:16.196805686 +0300
+++ src/backend/port/sysv_shmem.c	2014-07-01 21:22:49.171498000 +0300
@@ -54,7 +54,15 @@
 #define MAP_HASSEMAPHORE		0
 #endif
 
-#define PG_MMAP_FLAGS			(MAP_SHARED|MAP_ANONYMOUS|MAP_HASSEMAPHORE)
+#if defined(MAP_SHARED_PHYS) && defined(MAP_PREFAULT_READ)
+#define	PG_MAP_EXTRA	MAP_SHARED_PHYS|MAP_PREFAULT_READ
+#elif defined(MAP_SHARED_PHYS)
+#define	PG_MAP_EXTRA	MAP_SHARED_PHYS
+#else
+#define	PG_MAP_EXTRA	0
+#endif
+
+#define PG_MMAP_FLAGS			(MAP_SHARED|MAP_ANONYMOUS|MAP_HASSEMAPHORE|PG_MAP_EXTRA)
 
 /* Some really old systems don't define MAP_FAILED. */
 #ifndef MAP_FAILED