NAME¶
vm_map_find
—
find a free region within a map, and optionally map a
vm_object
SYNOPSIS¶
#include
<sys/param.h>
#include
<vm/vm.h>
#include
<vm/vm_map.h>
int
vm_map_find
(
vm_map_t
map,
vm_object_t object,
vm_ooffset_t offset,
vm_offset_t *addr,
vm_size_t length,
vm_offset_t max_addr,
int find_space,
vm_prot_t prot,
vm_prot_t max,
int
cow);
DESCRIPTION¶
The
vm_map_find
() function attempts to find a
free region in the target
map, with the given
length. If a free region is found,
vm_map_find
() creates a mapping of
object via a call to
vm_map_insert(9).
The arguments
offset,
prot,
max,
and
cow are passed unchanged to
vm_map_insert(9) when creating the mapping, if
and only if a free region is found.
If
object is
non-
NULL
, the reference count on the object
must be incremented by the caller before calling this function to account for
the new entry.
If
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
max_addr.
The
find_space argument specifies the strategy
to use when searching for a free region of the requested length. For all
values other than
VMFS_NO_SPACE
,
vm_map_findspace(9) is called to locate a free
region of the requested length with a starting address at or above
*addr. The following strategies are
supported:
VMFS_NO_SPACE
- The mapping will only succeed if there is a free region of the requested
length at the given address *addr.
VMFS_ANY_SPACE
- The mapping will succeed as long as there is a free region.
VMFS_SUPER_SPACE
- The mapping will succeed as long as there is a free region that begins on
a superpage boundary. If object is
non-
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.
VMFS_OPTIMAL_SPACE
- The mapping will succeed as long as there is a free region. However, if
object is
non-
NULL
and is already backed by
superpages, this strategy will attempt to find a free region aligned
relative to the existing superpages.
VMFS_ALIGNED_SPACE
(n)
- The mapping will succeed as long as there is a free region that aligns on
a 2^n boundary.
IMPLEMENTATION NOTES¶
This function acquires a lock on
map by calling
vm_map_lock(9), and holds it until the function
returns.
The search for a free region is defined to be first-fit, from the address
addr onwards.
RETURN VALUES¶
The
vm_map_find
() function returns
KERN_SUCCESS
if the mapping was
successfully created. If space could not be found or
find_space was
VMFS_NO_SPACE
and the given address,
addr, was already mapped,
KERN_NO_SPACE
will be returned. If the
discovered range turned out to be bogus,
KERN_INVALID_ADDRESS
will be returned.
SEE ALSO¶
vm_map(9),
vm_map_findspace(9),
vm_map_insert(9),
vm_map_lock(9)
AUTHORS¶
This manual page was written by
Bruce M
Simpson ⟨bms@spc.org⟩.