vm_map_find — find a free region within a map, and optionally map a vm_object

       This manual page was written by Bruce M Simpson <bms@spc.org>.

Debian                                         September 12, 2013                                 VM_MAP_FIND(9)

       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.

       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.

       vm_map_find — find a free region within a map, and optionally map a vm_object

       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.

vm_map(9), vm_map_findspace(9), vm_map_insert(9), vm_map_lock(9)

#include<sys/param.h>#include<vm/vm.h>#include<vm/vm_map.h>intvm_map_find(vm_map_tmap,  vm_object_tobject,  vm_ooffset_toffset, vm_offset_t*addr, vm_size_tlength,
           vm_offset_tmax_addr, intfind_space, vm_prot_tprot, vm_prot_tmax, intcow);