Using Shared Memory in Network Drivers
Miniport drivers for bus-master direct memory access (DMA) devices allocate shared memory for use by the network interface card (NIC) and the miniport driver.
NdisMAllocateSharedMemory can be called by a bus-master miniport driver to allocate memory for permanent sharing between the network adapter and the miniport driver. This function returns a virtual address and a physical address for the shared memory. The addresses are valid until a call to NdisMFreeSharedMemory frees the memory.