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Dynamic Creation of a NIC Switch

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A network adapter that supports single root I/O virtualization (SR-IOV) must be able to create a NIC switch. For some adapters, the NIC switch can be created dynamically after the miniport driver has returned from the call to MiniportInitializeEx.

Only the miniport driver for the PCI Express (PCIe) Physical Function (PF) of the SR-IOV adapter can create a NIC switch on the adapter.

Note  Starting with Windows Server 2012, the SR-IOV interface supports only one NIC switch on the network adapter. This switch is known as the default NIC switch, and is referenced by the NDIS_DEFAULT_SWITCH_ID identifier.

NDIS issues an object identifier (OID) method request of OID_NIC_SWITCH_CREATE_SWITCH to create a NIC switch on the SR-IOV network adapter. The InformationBuffer member of the NDIS_OID_REQUEST structure contains a pointer to the NDIS_NIC_SWITCH_PARAMETERS structure that contains the parameters for the switch.

If the PF miniport driver supports dynamic NIC switch creation, it must follow these steps when it handles this OID request:

  1. The PF miniport driver allocates the necessary hardware and software resources for the NIC switch based on these parameters. The driver also configures the network adapter with these parameters.

    Note  PF miniport drivers that support dynamic NIC switch creation do not have to read the switch parameters through the standardized SR-IOV keyword settings in the registry. NDIS reads these keywords to initialize the NDIS_NIC_SWITCH_PARAMETERS structure before it issues the OID_NIC_SWITCH_CREATE_SWITCH request. For more information on these keywords, see Standardized INF Keywords for SR-IOV.

  2. The miniport driver calls NdisMEnableVirtualization to enable SR-IOV and set the number of VFs on the network adapter. This function configures the SR-IOV Extended Capability in adapter's PCI configuration space. If this function returns NDIS_STATUS_SUCCESS, SR-IOV is enabled and the VFs are exposed over the PCIe interface.

For more information on how to handle the OID_NIC_SWITCH_CREATE_SWITCH request, see Handling the OID_NIC_SWITCH_CREATE_SWITCH Request.