Allocating Backfill for the Data Buffer
NDIS specifies the amount of data backfill space that the miniport driver should allocate in the BackfillSize member of the NDIS_HD_SPLIT_ATTRIBUTES structure. For more information about setting header-data split attributes, see Initializing a Header-Data Split Provider.
When a NIC splits the header and data in a received Ethernet frame, the miniport driver must pre-allocate backfill storage of at least the number of bytes that BackfillSize specifies before the starting address of data portion of the frame. The backfill storage must not cross a page boundary.
The driver stack can use the pre-allocated backfill storage to copy the header portion of the frame and create a virtually contiguous frame for network drivers that cannot handle split Ethernet frames.