diff --git a/include/mach/mach4.defs b/include/mach/mach4.defs
index 114edf4..4ecc0f5 100644
--- a/include/mach/mach4.defs
+++ b/include/mach/mach4.defs
@@ -110,3 +110,18 @@ routine memory_object_create_proxy(
 		start		: vm_offset_array_t;
 		len		: vm_offset_array_t;
 		out proxy	: mach_port_t);
+
+
+/*
+ *	Specify that the range of the virtual address space
+ *	of the task must not cause page faults for
+ *	the indicated accesses.
+ *
+ *	[ To unwire the pages, specify VM_PROT_NONE. ]
+ */
+routine	vm_task_wire(
+		task		: vm_task_t;
+		address		: vm_address_t;
+		size		: vm_size_t;
+		access		: vm_prot_t);
+
diff --git a/vm/vm_map.c b/vm/vm_map.c
index 6b13724..ae3ce21 100644
--- a/vm/vm_map.c
+++ b/vm/vm_map.c
@@ -208,6 +208,7 @@ void vm_map_setup(
 	rbtree_init(&map->hdr.tree);
 
 	map->size = 0;
+	map->user_wired = 0;
 	map->ref_count = 1;
 	map->pmap = pmap;
 	map->min_offset = min;
@@ -1409,7 +1410,10 @@ kern_return_t vm_map_pageable_common(
 
 		    if (user_wire) {
 			if (--(entry->user_wired_count) == 0)
+			{
+			    map->user_wired -= entry->vme_end - entry->vme_start;
 			    entry->wired_count--;
+			}
 		    }
 		    else {
 			entry->wired_count--;
@@ -1486,7 +1490,10 @@ kern_return_t vm_map_pageable_common(
 
 		    if (user_wire) {
 			if ((entry->user_wired_count)++ == 0)
+			{
+			    map->user_wired += entry->vme_end - entry->vme_start;
 			    entry->wired_count++;
+			}
 		    }
 		    else {
 			entry->wired_count++;
@@ -1512,6 +1519,7 @@ kern_return_t vm_map_pageable_common(
 				(entry->vme_end > start)) {
 				    if (user_wire) {
 					if (--(entry->user_wired_count) == 0)
+					    map->user_wired -= entry->vme_end - entry->vme_start;
 					    entry->wired_count--;
 				    }
 				    else {
@@ -1627,6 +1635,8 @@ void vm_map_entry_delete(
 	    if (entry->wired_count != 0) {
 		vm_fault_unwire(map, entry);
 		entry->wired_count = 0;
+		if (entry->user_wired_count)
+		    map->user_wired -= entry->vme_end - entry->vme_start;
 		entry->user_wired_count = 0;
 	    }
 
@@ -2274,6 +2284,8 @@ start_pass_1:
 			entry->offset = copy_entry->offset;
 			entry->needs_copy = copy_entry->needs_copy;
 			entry->wired_count = 0;
+			if (entry->user_wired_count)
+			    dst_map->user_wired -= entry->vme_end - entry->vme_start;
 			entry->user_wired_count = 0;
 
 			vm_map_copy_entry_unlink(copy, copy_entry);
@@ -2869,6 +2881,7 @@ create_object:
 
 	if (must_wire) {
 		entry->wired_count = 1;
+		dst_map->user_wired += entry->vme_end - entry->vme_start;
 		entry->user_wired_count = 1;
 	} else {
 		entry->wired_count = 0;
@@ -3954,6 +3967,8 @@ retry:
 
 					assert(src_entry->wired_count > 0);
 				        src_entry->wired_count = 0;
+					if (src_entry->user_wired_count)
+					    src_map->user_wired -= src_entry->vme_end - src_entry->vme_start;
 				        src_entry->user_wired_count = 0;
 					unwire_end = src_entry->vme_end;
 				        pmap_pageable(vm_map_pmap(src_map),
diff --git a/vm/vm_map.h b/vm/vm_map.h
index fc7730a..9b31f90 100644
--- a/vm/vm_map.h
+++ b/vm/vm_map.h
@@ -170,6 +170,7 @@ struct vm_map {
 #define max_offset		hdr.links.end	/* end of range */
 	pmap_t			pmap;		/* Physical map */
 	vm_size_t		size;		/* virtual size */
+	vm_size_t		user_wired;	/* wired by user size */
 	int			ref_count;	/* Reference count */
 	decl_simple_lock_data(,	ref_lock)	/* Lock for ref_count field */
 	vm_map_entry_t		hint;		/* hint for quick lookups */
diff --git a/vm/vm_user.c b/vm/vm_user.c
index f7c87cc..e62dc42 100644
--- a/vm/vm_user.c
+++ b/vm/vm_user.c
@@ -431,3 +431,37 @@ kern_return_t vm_wire(host, map, start, size, access)
 				    round_page(start+size),
 				    access);
 }
+
+/*
+ *	Specify that the range of the virtual address space
+ *	of the target task must not cause page faults for
+ *	the indicated accesses.
+ *
+ *	[ To unwire the pages, specify VM_PROT_NONE. ]
+ */
+kern_return_t vm_task_wire(task, start, size, access)
+	vm_map_t		task;
+	vm_offset_t		start;
+	vm_size_t		size;
+	vm_prot_t		access;
+{
+	if (task == VM_MAP_NULL)
+		return KERN_INVALID_TASK;
+
+	if (access & ~VM_PROT_ALL)
+		return KERN_INVALID_ARGUMENT;
+
+	/*Check if range includes projected buffer;
+	  user is not allowed direct manipulation in that case*/
+	if (projected_buffer_in_range(task, start, start+size))
+		return(KERN_INVALID_ARGUMENT);
+
+	/* TODO: make it tunable */
+	if (access != VM_PROT_NONE && task->user_wired + size > 65536)
+		return KERN_NO_ACCESS;
+
+	return vm_map_pageable_user(task,
+				    trunc_page(start),
+				    round_page(start+size),
+				    access);
+}