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>.