freebsd man page for vm_map_find

VM_MAP_FIND(9)						   BSD Kernel Developer's Manual					    VM_MAP_FIND(9)

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>.

BSD
								September 12, 2013							       BSD