W_INITIATE_OFFLOAD_HANDLER callback function (ndischimney.h)

[The TCP chimney offload feature is deprecated and should not be used.]

MiniportInitiateOffload offloads TCP chimney state from the host stack.

Syntax

W_INITIATE_OFFLOAD_HANDLER WInitiateOffloadHandler;

void WInitiateOffloadHandler(
  [in]      IN NDIS_HANDLE MiniportAdapterContext,
  [in, out] IN OUT PNDIS_MINIPORT_OFFLOAD_BLOCK_LIST OffloadBlockList
)
{...}

Parameters

[in] MiniportAdapterContext

The handle to an offload-target allocated context area in which the offload target maintains state information about this instance of the adapter. The miniport driver provided this handle to NDIS when it called NdisMSetMiniportAttributes from its MiniportInitializeEx function.

[in, out] OffloadBlockList

A pointer to an NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structure that can be a stand-alone structure or the root of a linked list of such structures.

Return value

None

Remarks

The MiniportInitiateOffload function stores the OffloadBlockList pointer and then returns. The offload target always completes the offload operation asynchronously by calling NdisMInitiateOffloadComplete. The state tree pointed to by the OffloadBlockList pointer is valid until the miniport driver calls NdisMInitiateOffloadComplete.

After returning from its MiniportInitiateOffload function, the offload target offloads state from the state tree. An NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structure whose MiniportOffloadContext member points to a memory location that contains a NULL value is followed by state to be offloaded. For more information, see Storing and Referencing Offloaded State. The Header member of an NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structure contains a Type member that specifies the type of offload state, and by implication, the offload state structure or structures, that immediately follow the NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structure in memory.

The offload target offloads the offload state associated with an NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structure into an offload context area. For more information, see Storing and Referencing Offloaded State.

When offloading state, the offload target must traverse the state tree in depth-first/breadth-next fashion. It is critical that an offload target offloads state in this way.

Some of the NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structures in the state tree that are passed to the MiniportInitiateOffload function can be placeholders or linking nodes that do not have accompanying state to be offloaded. For more information, see Placeholders, Linkers, and New Offloads.

The offload target can receive buffered data from the host stack for a connection that is being offloaded. The offload target must copy this data into its own buffer before completing the offload operation. For more information about processing buffered receive data, see Handling Buffered Receive Data During and After an Offload Operation.

For each state object that it offloads, the offload target must also supply a PVOID value that references the offload context area in which the offload target stores the state object. The offload target writes this PVOID value to the memory location pointed to by the *MiniportOffloadContext member of the NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structure associated with the state. If the offload target did not successfully offload the state associated with the NDIS_MINIPORT_OFFLOAD_BLOCK_LIST structure, it should not write a value to the memory location pointed to by the *MiniportOffloadContext member. For more information, see Storing and Referencing Offloaded State.

Requirements

See also

MiniportInitializeEx

NdisMInitiateOffloadComplete

NdisMSetMiniportAttributes