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110 lines
3.4 KiB
Groff
110 lines
3.4 KiB
Groff
.\"
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.\" Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 19, 2003
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.Dt vm_map_wire 9
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.Sh NAME
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.Nm vm_map_wire ,
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.Nm vm_map_unwire
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.Nd manage page wiring within a virtual memory map
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.Sh SYNOPSIS
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.In sys/param.h
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.In vm/vm.h
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.In vm/vm_map.h
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.Ft int
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.Fn vm_map_wire "vm_map_t map" "vm_offset_t start" "vm_offset_t end" "int flags"
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.Ft int
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.Fn vm_map_unwire "vm_map_t map" "vm_offset_t start" "vm_offset_t end" "int flags"
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.Sh DESCRIPTION
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The
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.Fn vm_map_wire
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function is responsible for wiring pages in the range between
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.Fa start
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and
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.Fa end
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within the map
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.Fa map .
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Wired pages are locked into physical memory, and may not be paged out
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as long as their wire count remains above zero.
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.Pp
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The
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.Fn vm_map_unwire
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function performs the corresponding unwire operation.
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.Pp
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The
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.Fa flags
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argument is a bit mask, consisting of the following flags:
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.Pp
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If the
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.Dv VM_MAP_WIRE_USER
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flag is set, the function operates within user address space.
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.Pp
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If the
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.Dv VM_MAP_WIRE_HOLESOK
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flag is set, it may operate upon an arbitrary range within the
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address space of
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.Fa map .
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.Pp
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If a contiguous range is desired, callers should explicitly express
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their intent by specifying the
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.Dv VM_MAP_WIRE_NOHOLES
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flag.
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.Sh IMPLEMENTATION NOTES
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Both functions will attempt to acquire a lock on the map using
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.Xr vm_map_lock 9
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and hold it for the duration of the call.
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If they detect
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.Dv MAP_ENTRY_IN_TRANSITION ,
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they will call
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.Xr vm_map_unlock_and_wait 9
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until the map becomes available again.
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.Pp
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The map could have changed during this window as it was held by another
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consumer, therefore consumers of this interface should check for this
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condition using the return values below.
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.Sh RETURN VALUES
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The
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.Fn vm_map_wire
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and
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.Fn vm_map_unwire
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functions have identical return values.
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The functions return
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.Dv KERN_SUCCESS
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if all pages within the range were [un]wired successfully.
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.Pp
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Otherwise, if the specified range was not valid,
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or if the map changed while the MAP_ENTRY_IN_TRANSITION flag was set,
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.Dv KERN_INVALID_ADDRESS
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is returned.
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.Sh SEE ALSO
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.Xr mlockall 2 ,
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.Xr munlockall 2 ,
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.Xr vm_map 9
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.Sh AUTHORS
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This man page was written by
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.An Bruce M Simpson Aq bms@spc.org .
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