/share/man/man9/vm_map_wire.9

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 26.\" $FreeBSD$
 27.\"
 28.Dd July 19, 2003
 29.Dt VM_MAP_WIRE 9
 30.Os
 31.Sh NAME
 32.Nm vm_map_wire ,
 33.Nm vm_map_unwire
 34.Nd manage page wiring within a virtual memory map
 35.Sh SYNOPSIS
 36.In sys/param.h
 37.In vm/vm.h
 38.In vm/vm_map.h
 39.Ft int
 40.Fn vm_map_wire "vm_map_t map" "vm_offset_t start" "vm_offset_t end" "int flags"
 41.Ft int
 42.Fo vm_map_unwire
 43.Fa "vm_map_t map" "vm_offset_t start" "vm_offset_t end" "int flags"
 44.Fc
 45.Sh DESCRIPTION
 46The
 47.Fn vm_map_wire
 48function is responsible for wiring pages in the range between
 49.Fa start
 50and
 51.Fa end
 52within the map
 53.Fa map .
 54Wired pages are locked into physical memory, and may not be paged out
 55as long as their wire count remains above zero.
 56.Pp
 57The
 58.Fn vm_map_unwire
 59function performs the corresponding unwire operation.
 60.Pp
 61The
 62.Fa flags
 63argument is a bit mask, consisting of the following flags:
 64.Pp
 65If the
 66.Dv VM_MAP_WIRE_USER
 67flag is set, the function operates within user address space.
 68.Pp
 69If the
 70.Dv VM_MAP_WIRE_HOLESOK
 71flag is set, it may operate upon an arbitrary range within the
 72address space of
 73.Fa map .
 74.Pp
 75If a contiguous range is desired, callers should explicitly express
 76their intent by specifying the
 77.Dv VM_MAP_WIRE_NOHOLES
 78flag.
 79.Sh IMPLEMENTATION NOTES
 80Both functions will attempt to acquire a lock on the map using
 81.Xr vm_map_lock 9
 82and hold it for the duration of the call.
 83If they detect
 84.Dv MAP_ENTRY_IN_TRANSITION ,
 85they will call
 86.Xr vm_map_unlock_and_wait 9
 87until the map becomes available again.
 88.Pp
 89The map could have changed during this window as it was held by another
 90consumer, therefore consumers of this interface should check for this
 91condition using the return values below.
 92.Sh RETURN VALUES
 93The
 94.Fn vm_map_wire
 95and
 96.Fn vm_map_unwire
 97functions have identical return values.
 98The functions return
 99.Dv KERN_SUCCESS
100if all pages within the range were [un]wired successfully.
101.Pp
102Otherwise, if the specified range was not valid,
103or if the map changed while the
104.Dv MAP_ENTRY_IN_TRANSITION
105flag was set,
106.Dv KERN_INVALID_ADDRESS
107is returned.
108.Sh SEE ALSO
109.Xr mlockall 2 ,
110.Xr munlockall 2 ,
111.Xr vm_map 9
112.Sh AUTHORS
113This manual page was written by
114.An Bruce M Simpson Aq bms@spc.org .