freebsd-dev/share/man/man9/vm_map_find.9

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.Dd May 10, 2008
.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
.In sys/param.h
.In vm/vm.h
.In 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" "int find_space"
.Fa "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 ,
and will also optionally create a mapping of
.Fa object .
.Pp
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.
.Pp
If
.Fa object
is
.Pf 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.
.Pp
If
.Fa find_space
is either
.Dv VMFS_ALIGNED_SPACE 
or
.Dv VMFS_ANY_SPACE ,
the function will call
.Xr vm_map_findspace 9
to discover a free region.
Moreover, if
.Fa find_space
is
.Dv VMFS_ALIGNED_SPACE ,
the address of the free region will be optimized for the use of superpages.
Otherwise, if
.Fa find_space
is
.Dv VMFS_NO_SPACE ,
.Xr vm_map_insert 9
is called with the given address,
.Fa addr .
.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.
.Pp
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 .