## Virtual Device Driver Reference for OS/2

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### VDHMapPages Parameter - flMappingFlag

flMappingFlag (ULONG) Mapping options flag.

Possible values are:

VDHMT_INVALID Make target region pages invalid. vdhmt_hmap can be 0 (zero). This service is faster when the handle is provided, but virtual device drivers that do not store handles can map to invalid before remapping a region. Note that pvdhmsSourceRegion is ignored.

VDHMT_LINEAR Map linear source region into target region. vdhms_laddr contains the linear address to map at the start of the target region. This can only be a page-granular address in a memory allocation that was obtained by using VDHAllocPages or VDHReallocPages. After a successful mapping, the target region aliases the corresponding region of the source.

vdhms_hobj must be 0 (zero) the first time a newly allocated or reallocated source object is mapped. On a successful mapping, vdhms_hobj is filled in. Using this handle on the next mapping that uses the same source object speeds up that mapping call. Any linear address (laddr) at the start of the target region can be mapped using the handle. The returned result must be stored after each mapping call. Virtual device drivers can avoid storing this handle and always use 0 (zero), however, the call will be slower.

VDHMT_PHYSICAL Map physical source region into target region. vdhms_laddr contains the physical address to map at the start of the target region. vdhms_hobj is ignored.

VDHMT_BLACK_HOLE Map target region to black hole pages. pvdhmsSourceRegion is ignored.