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Determining SR-IOV Capabilities

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This topic describes how NDIS and overlying drivers determine the single root I/O virtualization (SR-IOV) capabilities of a network adapter. This topic contains the following information:

Reporting SR-IOV Capabilities during MiniportInitializeEx

Querying SR-IOV Capabilities by Overlying Drivers

Reporting SR-IOV Capabilities during MiniportInitializeEx

When NDIS calls the miniport driver's MiniportInitializeEx function, the driver provides the following SR-IOV capabilities:

  • The complete set of SR-IOV hardware capabilities that the network adapter can support.

  • The SR-IOV capabilities that are currently enabled on the network adapter.

  • Whether the miniport driver is managing the PCI Express (PCIe) Physical Function (PF) or Virtual Function (VF) on the network adapter.

The miniport driver reports the SR-IOV hardware capabilities of the underlying network adapter through an NDIS_SRIOV_CAPABILITIES structure that is initialized in the following way:

  1. The miniport driver initializes the Header member. The driver sets the Type member of Header to NDIS_OBJECT_TYPE_DEFAULT.

    Starting with NDIS 6.30, the miniport driver sets the Revision member of Header to NDIS_SRIOV_CAPABILITIES _REVISION_1 and the Size member to NDIS_SIZEOF_SRIOV_CAPABILITIES_REVISION_1.

  2. The miniport driver sets the appropriate flags in the SriovCapabilities member to report SR-IOV capabilities.

    If the network adapter supports SR-IOV, the miniport driver for the PCI Express (PCIe) Physical Function of the adapter must set the following flags:

    • NDIS_SRIOV_CAPS_SRIOV_SUPPORTED

    • NDIS_SRIOV_CAPS_PF_MINIPORT

    Note

     The miniport driver for a PCIe Virtual Function (VF) of the network adapter must set both the NDIS_SRIOV_CAPS_VF_MINIPORT flag and the NDIS_SRIOV_CAPS_SRIOV_SUPPORTED flag.  

When NDIS calls the miniport driver's MiniportInitializeEx function, the driver registers the SR-IOV capabilities of the network adapter by following these steps:

  1. The miniport driver initializes an NDIS_MINIPORT_ADAPTER_HARDWARE_ASSIST_ATTRIBUTES structure.

    The miniport driver sets the HardwareSriovCapabilities member to a pointer to the previously initialized NDIS_SRIOV_CAPABILITIES structure.

    If the registry setting for the *SRIOV INF keyword has a value of one, the SR-IOV capabilities are currently enabled on the network adapter. The miniport driver sets the CurrentSriovCapabilities members to a pointer to the same NDIS_SRIOV_CAPABILITIES structure.

    If the registry setting for the *SRIOV INF keyword has a value of zero, the SR-IOV capabilities are currently disabled on the network adapter. The miniport driver must set the CurrentSriovCapabilities member to NULL.

    For more information about the *SRIOV INF keyword, see Standardized INF Keywords for SR-IOV.

  2. The driver calls NdisMSetMiniportAttributes and sets the MiniportAttributes parameter to a pointer to the NDIS_MINIPORT_ADAPTER_HARDWARE_ASSIST_ATTRIBUTES structure.

For more information about the adapter initialization process, see Initializing a Miniport Adapter.

Querying SR-IOV Capabilities by Overlying Drivers

NDIS passes the network adapter's currently enabled SR-IOV capabilities to overlying drivers that bind to the network adapter in the following way:

  • When NDIS calls an overlying filter driver's FilterAttach function, NDIS passes the network adapter's SR-IOV capabilities through the AttachParameters parameter. This parameter contains a pointer to an NDIS_FILTER_ATTACH_PARAMETERS structure. The SriovCapabilities member of this structure contains a pointer to an NDIS_SRIOV_CAPABILITIES structure.

  • When NDIS calls an overlying protocol driver's ProtocolBindAdapterEx function, NDIS passes the network adapter's SR-IOV capabilities through the BindParameters parameter. This parameter contains a pointer to an NDIS_FILTER_ATTACH_PARAMETERS structure. The SriovCapabilities member of this structure contains a pointer to an NDIS_SRIOV_CAPABILITIES structure.

NDIS also returns the NDIS_SRIOV_CAPABILITIES structure when it handles object identifier (OID) query requests of OID_SRIOV_HARDWARE_CAPABILITIES and OID_SRIOV_CURRENT_CAPABILITIES that are issued by overlying protocol or filter drivers.