NdisAllocateBuffer参数问题

VOID  NdisAllocateBuffer(
    OUT PNDIS_STATUS  Status,
    OUT PNDIS_BUFFER  *Buffer,
    IN NDIS_HANDLE  PoolHandle,
    IN PVOID  VirtualAddress,
    IN UINT  Length
    );
请问其中PoolHandle和 VirtualAddress分别是什么意思啊？？
（附英文解释：
PoolHandle
              Specifies the handle returned by a preceding call to NdisAllocateBufferPool.
VirtualAddress
              Pointer to the base virtual address of previously allocated system-space memory to be mapped in the returned buffer descriptor.
）