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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>.