2.4 Miniport NIC Driver Operations

To begin network communications, the miniport must register itself with the NDIS library and initialize its device. The miniport NIC driver also allocates memory for the packets and buffers it needs. After this initialization step, protocol drivers can bind to the NIC managed by the miniport and submit requests to the underlying NIC miniport. To submit requests, a protocol driver calls the NDIS library supplying the handle to the NIC returned from its call to NdisOpenAdapter. The NDIS library, in turn, calls one of the upper-edge functions in the miniport.

A Typical Miniport Operation

Sending a packet across the network is a typical operation involving the miniport. The following describes a common asynchronous operation:

1. To communicate with its remote-node peer, a highest-level protocol driver on a local node repackages messages from upper level network layers into data packets. The protocol driver then calls NDIS with the packet.

2. Assuming no intermediate NDIS driver between the highest level protocol driver and the miniport NIC driver, NDIS calls the miniport’s MiniportSend function with a pointer to the packet.

3. The NIC driver sets up its device, starts the send operation and returns NDIS_STATUS_PENDING to NDIS.

4. When the NIC has finished transmitting the packet, it generates an interrupt, which causes a call to the NDIS library.

5. The NDIS library calls the MiniportISR function for the NIC.

6. The miniport NIC driver performs only the minimum necessary work in MiniportISR and returns, deferring most of the interrupt handling to its MiniportHandleInterrupt function.

7. The NDIS library’s deferred processing function runs and then calls MiniportHandleInterrupt to complete interrupt processing for the transmission. MiniportHandleInterrupt completes the send and calls NdisMSendComplete. NDIS calls the appropriate protocol driver’s ProtocolSendComplete function. A NIC driver can wait to call NdisMSendComplete until it has completed several transmits.

When return data is available from the remote node, the NIC captures the data and interrupts. NDIS intercepts the interrupt and signals its miniport drive either by calling MiniportISR or MiniportHandleInterrupt. The miniport copies the data to a buffer and calls NdisM...IndicateReceive. NDIS notifies the protocol driver of incoming packets by calling its ProtocolReceive function and subsequently the miniport’s MiniportTransferData function is called to transfer the data to a protocol driver-supplied packet.

NDIS Library Operations

The NdisXxx functions for miniports in the NDIS library assist in handling multiprocessor synchronization operations, protocol filters, and hardware problems on the NIC.

• The NDIS library queues requests from different processors and sends them to the miniport when the driver is free.

• The NDIS library multiplexes requests from different protocols onto a single miniport NIC driver for a specific network card.

• The NDIS library has a built-in deadman timer that calls the MiniportCheckForHang function periodically to detect problems on the network interface card.

Miniport Driver Operations

The NDIS library maintains a driver-descriptor block for each miniport NIC driver that registers itself on a network. The descriptor block contains the addresses of the upper-edge functions exported by the miniport. With the exception of MiniportISR, MiniportInitialize, possibly MiniportShutdown and possibly MiniportHalt, miniport processing occurs at IRQL DISPATCH_LEVEL. Typical operations are:

• Initializing the NDIS library and registering the NIC driver.

• Registering a network interface card.

• Sending data.

• Indicating and, possibly transferring received data.

• Indicating status.

• Querying and setting NIC and driver capabilities.

• Querying global statistics (per network interface card).

• Resetting a network interface card.

• Removing a network interface card.

• Unloading and deregistering drivers and terminating the NDIS library.

For help in following the descriptions, refer to the function definitions in Section 2.3. For more descriptions of the functions, refer to the Network Driver Reference.