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
Thevm_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-
NULLand 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-
NULLand 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>.