EVT_NET_ADAPTER_RECEIVE_SCALING_ENABLE callback function

Description

The EvtNetAdapterReceiveScalingEnable callback function is implemented by the client driver to enable receive side scaling (RSS) for a network interface controller (NIC).

Parameters

Adapter [_In_]

The NETADAPTER object the client driver obtained in a previous call to NetAdapterCreate.

HashType [_In_]

A NET_ADAPTER_RECEIVE_SCALING_HASH_TYPE value that specifies the type of receive side scaling (RSS) hash function that a NIC should use to compute the hash values for incoming packets.

ProtocolType [_In_]

A NET_ADAPTER_RECEIVE_SCALING_PROTOCOL_TYPE value that specifies the portion of received network data that an RSS-capable NIC must use to calculate an RSS hash value.

Return value

Returns STATUS_SUCCESS if RSS was successfully enabled. Otherwise, returns an appropriate NTSTATUS error code.

Prototype

//Declaration

EVT_NET_ADAPTER_RECEIVE_SCALING_ENABLE EvtNetAdapterReceiveScalingEnable;

// Definition

NTSTATUS EvtNetAdapterReceiveScalingEnable
(
    _In_ NETADAPTER Adapter,
    _In_ NET_ADAPTER_RECEIVE_SCALING_HASH_TYPE HashType,
    _In_ NET_ADAPTER_RECEIVE_SCALING_PROTOCOL_TYPE ProtocolType
)
{...}

typedef EVT_NET_ADAPTER_RECEIVE_SCALING_ENABLE *PFN_NET_ADAPTER_RECEIVE_SCALING_ENABLE;

Remarks

Register your implementation of this callback function by setting the appropriate member of the NET_ADAPTER_RECEIVE_SCALING_CAPABILITIES structure and then calling NetAdapterSetReceiveScalingCapabilities. Client drivers typically call NetAdapterSetReceiveScalingCapabilities when starting a net adapter, before calling NetAdapterStart.

Example

In this callback, clients turn RSS on with the supplied information by setting the appropriate control bits in hardware.

[!IMPORTANT] Client drivers should not clear or reset their indirection table from their EvtNetAdapterReceiveScalingEnable callback. The framework will set the driver's initial indirection table state.

NTSTATUS
MyEvtNetAdapterReceiveScalingEnable(
    _In_ NETADAPTER Adapter,
    _In_ NET_ADAPTER_RECEIVE_SCALING_HASH_TYPE HashType,
    _In_ NET_ADAPTER_RECEIVE_SCALING_PROTOCOL_TYPE ProtocolType
)
{
    NTSTATUS status = STATUS_SUCCESS;

    // Not using the hash type in this example
    UNREFERENCED_PARAMETER(HashType);

    UINT32 controlBitsEnable = MY_RSS_MULTI_CPU_ENABLE | MY_RSS_HASH_BITS_ENABLE;

    // Set the appropriate control bits for IPv4
    if(ProtocolType & NetAdapterReceiveScalingProtocolTypeIPv4)
    {
        controlBitsEnable |= MY_RSS_IPV4_ENABLE;

        if (ProtocolType & NetAdapterReceiveScalingProtocolTypeTcp)
        {
            controlBitsEnable |= MY_RSS_IPV4_TCP_ENABLE;
        }
    }

    // Repeat for IPv6
    ...

    // Set the bits in hardware
    if(!MyHardwareRssSetControl(controlBitsEnable))
    {
        WdfDeviceSetFailed(Adapter->WdfDevice, WdfDeviceFailedAttemptRestart);
        return STATUS_UNSUCCESSFUL;
    }

    // Perform other tasks like restarting the Rx queue

    return STATUS_SUCCESS;
}

See also

EvtNetAdapterReceiveScalingDisable

NetAdapterCx Receive Side Scaling