VM_MAP_FINDSPACE(9) BSD Kernel Developer's Manual VM_MAP_FINDSPACE(9)NAME
vm_map_findspace -- find a free region within a map
SYNOPSIS
#include <sys/param.h>
#include <vm/vm.h>
#include <vm/vm_map.h>
int
vm_map_findspace(vm_map_t map, vm_offset_t start, vm_size_t length, vm_offset_t *addr);
DESCRIPTION
The vm_map_findspace() function attempts to find a region with sufficient space in the map for an object of size length at the address addr.
IMPLEMENTATION NOTES
It is the caller's responsibility to obtain a lock on the map using vm_map_lock(9) before calling this function.
This routine may call pmap_growkernel(9) to grow the kernel's address space, if and only if the mapping is being made within the kernel
address space, and if insufficient space remains in the kernel_map.
RETURN VALUES
The vm_map_findspace() function returns the value 0 if successful, and *addr will contain the first virtual address in the found region; oth-
erwise, the value 1 is returned.
SEE ALSO pmap_growkernel(9), vm_map(9), vm_map_entry_resize_free(9), vm_map_lock(9)AUTHORS
This manual page was written by Bruce M Simpson <bms@spc.org>.
BSD July 19, 2003 BSD
Check Out this Related Man Page
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