Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
$FreeBSD$
.Dd September 12, 2013 .Dt VM_MAP_FIND 9 .Os .Sh NAME .Nm vm_map_find .Nd find a free region within a map, and optionally map a vm_object .Sh SYNOPSIS n sys/param.h n vm/vm.h n vm/vm_map.h .Ft int .Fo vm_map_find .Fa "vm_map_t map" "vm_object_t object" "vm_ooffset_t offset" .Fa "vm_offset_t *addr" "vm_size_t length" "vm_offset_t max_addr" .Fa "int find_space" "vm_prot_t prot" "vm_prot_t max" "int cow" .Fc .Sh DESCRIPTION The .Fn vm_map_find function attempts to find a free region in the target .Fa map , with the given .Fa length. If a free region is found, .Fn vm_map_find creates a mapping of .Fa object via a call to .Xr vm_map_insert 9 .
p The arguments .Fa offset , .Fa prot , .Fa max , and .Fa cow are passed unchanged to .Xr vm_map_insert 9 when creating the mapping, if and only if a free region is found.
p If .Fa object is
f non- Dv NULL , the reference count on the object must be incremented by the caller before calling this function to account for the new entry.
p If .Fa max_addr is non-zero, it specifies an upper bound on the mapping. The mapping will only succeed if a free region can be found that resides entirely below .Fa max_addr .
p The .Fa find_space argument specifies the strategy to use when searching for a free region of the requested length. For all values other than .Dv VMFS_NO_SPACE , .Xr vm_map_findspace 9 is called to locate a free region of the requested length with a starting address at or above .Fa *addr . The following strategies are supported: l -tag -width "Dv VMFS_ALIGNED_SPACE Ns" t Dv VMFS_NO_SPACE The mapping will only succeed if there is a free region of the requested length at the given address .Fa *addr . t Dv VMFS_ANY_SPACE The mapping will succeed as long as there is a free region. t Dv VMFS_SUPER_SPACE The mapping will succeed as long as there is a free region that begins on a superpage boundary. If .Fa object is
f non- Dv NULL and is already backed by superpages, then the mapping will require a free region that aligns relative to the existing superpages rather than one beginning on a superpage boundary. t Dv VMFS_OPTIMAL_SPACE The mapping will succeed as long as there is a free region. However, if .Fa object is
f non- Dv NULL and is already backed by superpages, this strategy will attempt to find a free region aligned relative to the existing superpages. t Dv VMFS_ALIGNED_SPACE Ns Pq Fa n The mapping will succeed as long as there is a free region that aligns on a
f 2^ Fa n boundary. .El .Sh IMPLEMENTATION NOTES This function acquires a lock on .Fa map by calling .Xr vm_map_lock 9 , and holds it until the function returns.
p The search for a free region is defined to be first-fit, from the address .Fa addr onwards. .Sh RETURN VALUES The .Fn vm_map_find function returns .Dv KERN_SUCCESS if the mapping was successfully created. If space could not be found or .Fa find_space was .Dv VMFS_NO_SPACE and the given address, .Fa addr , was already mapped, .Dv KERN_NO_SPACE will be returned. If the discovered range turned out to be bogus, .Dv KERN_INVALID_ADDRESS will be returned. .Sh SEE ALSO .Xr vm_map 9 , .Xr vm_map_findspace 9 , .Xr vm_map_insert 9 , .Xr vm_map_lock 9 .Sh AUTHORS This manual page was written by .An Bruce M Simpson Aq Mt bms@spc.org .