|VM_MAP_FIND(9)||FreeBSD Kernel Developer's Manual||VM_MAP_FIND(9)|
NAMEvm_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>
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);
DESCRIPTIONThe 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:
- The mapping will only succeed if there is a free region of the requested length at the given address *addr.
- The mapping will succeed as long as there is a free region.
- 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.
- 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 NOTESThis 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 VALUESThe 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.
AUTHORSThis manual page was written by <email@example.com>.
|September 12, 2013||FreeBSD|