--- //depot/vendor/freebsd/src/sys/sys/mman.h	2008/03/28 04:30:29
+++ //depot/user/jhb/pat/sys/mman.h	2009/05/13 13:56:34
@@ -87,6 +87,8 @@
  * Extended flags
  */
 #define	MAP_NOCORE	 0x00020000 /* dont include these pages in a coredump */
+#define	MAP_PREFAULT_READ 0x00040000 /* prefault mapping for reading */
+#define	MAP_PREFAULT_WRITE 0x00080000 /* prefault mapping for writing */
 #endif /* __BSD_VISIBLE */
 
 #if __POSIX_VISIBLE >= 199309
--- //depot/vendor/freebsd/src/sys/vm/vm_mmap.c	2009/04/04 23:15:14
+++ //depot/user/jhb/pat/vm/vm_mmap.c	2009/05/14 19:54:38
@@ -1471,6 +1507,22 @@
 	if ((rv == KERN_SUCCESS) && (map->flags & MAP_WIREFUTURE))
 		vm_map_wire(map, *addr, *addr + size,
 		    VM_MAP_WIRE_USER|VM_MAP_WIRE_NOHOLES);
+	else if ((rv == KERN_SUCCESS) &&
+	    (flags & (MAP_PREFAULT_READ | MAP_PREFAULT_WRITE))) {
+		vm_offset_t va;
+		vm_size_t len;
+		int prot;
+
+		prot = VM_PROT_READ;
+		if (flags & MAP_PREFAULT_WRITE)
+			prot |= VM_PROT_WRITE;
+		va = trunc_page(*addr);
+		len = size + (*addr - va);
+		for (; len > 0; va += PAGE_SIZE, len -= PAGE_SIZE) {
+			vm_fault(map, va, prot, (prot & VM_PROT_WRITE) ?
+			    VM_FAULT_DIRTY : VM_FAULT_NORMAL);
+		}
+	}
 
 	switch (rv) {
 	case KERN_SUCCESS: