Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
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$FreeBSD: releng/10.2/share/man/man9/vm_map_find.9 255525 2013-09-13 19:08:10Z joel $
.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 bms@spc.org .