vm_map_wirevm_map_unwire
- manage page wiring within a virtual memory map
SYNOPSIS
#include <sys/param.h>
#include <vm/vm.h>
#include <vm/vm_map.h> int
vm_map_wire (vm_map_t map vm_offset_t start vm_offset_t end int flags); int
Fo vm_map_unwire
Fa vm_map_t map vm_offset_t start vm_offset_t end int flags
Fc
DESCRIPTION
The
vm_map_wire ();
function is responsible for wiring pages in the range between
Fa start
and
Fa end
within the map
Fa map .
Wired pages are locked into physical memory, and may not be paged out
as long as their wire count remains above zero.
The
vm_map_unwire ();
function performs the corresponding unwire operation.
The
Fa flags
argument is a bit mask, consisting of the following flags:
If the
VM_MAP_WIRE_USER
flag is set, the function operates within user address space.
If the
VM_MAP_WIRE_HOLESOK
flag is set, it may operate upon an arbitrary range within the
address space of
Fa map .
If a contiguous range is desired, callers should explicitly express
their intent by specifying the
VM_MAP_WIRE_NOHOLES
flag.
IMPLEMENTATION NOTES
Both functions will attempt to acquire a lock on the map using
vm_map_lock9
and hold it for the duration of the call.
If they detect
MAP_ENTRY_IN_TRANSITION
they will call
vm_map_unlock_and_wait9
until the map becomes available again.
The map could have changed during this window as it was held by another
consumer, therefore consumers of this interface should check for this
condition using the return values below.
RETURN VALUES
The
vm_map_wire ();
and
vm_map_unwire ();
functions have identical return values.
The functions return
KERN_SUCCESS
if all pages within the range were [un]wired successfully.
Otherwise, if the specified range was not valid,
or if the map changed while the
MAP_ENTRY_IN_TRANSITION
flag was set,
KERN_INVALID_ADDRESS
is returned.
