NAME¶
vm_map_wire
,
vm_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
vm_map_unwire
(
vm_map_t
map,
vm_offset_t start,
vm_offset_t end,
int flags);
DESCRIPTION¶
The
vm_map_wire
() function is responsible for
wiring pages in the range between
start and
end within the map
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
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
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_lock(9) and hold it for the duration of
the call. If they detect
MAP_ENTRY_IN_TRANSITION
, they will call
vm_map_unlock_and_wait(9) 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.
SEE ALSO¶
mlockall(2),
munlockall(2),
vm_map(9)
AUTHORS¶
This manual page was written by
Bruce M
Simpson ⟨bms@spc.org⟩.