vm_map_wire(9)

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 un

wire operation.

The flags argument is a bit mask, consisting of the follow

ing 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 us

ing
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_un

lock_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 identi

cal 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_IN

VALID_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>.

BSD July 19, 2003

BSD