Standardized INF Keywords for VMQ

The following standardized INF keywords are defined to enable or disable support for the virtual machine queue (VMQ) features of network adapters.

*VMQ
A value that describes whether the device has enabled or disabled the VMQ feature.

*VMQLookaheadSplit
A value that describes whether the device has enabled or disabled the ability to split receive buffers into lookahead and post-lookahead buffers. The miniport driver reports this capability with the NDIS_RECEIVE_FILTER_LOOKAHEAD_SPLIT_SUPPORTED flag in the SupportedQueueProperties member of the NDIS_RECEIVE_FILTER_CAPABILITIES structure. For more information about this feature, see Shared Memory in Receive Buffers.

Note Starting with NDIS 6.30, splitting packet data into separate lookahead buffers is no longer supported. Starting with Windows Server 2012, this INF keyword is obsolete.

*VMQVlanFiltering
A value that describes whether the device has enabled or disabled the ability to filter network packets by using the VLAN identifier in the media access control (MAC) header. The miniport driver reports this capability with the NDIS_RECEIVE_FILTER_MAC_HEADER_VLAN_ID_SUPPORTED flag in SupportedMacHeaderFields member of the NDIS_RECEIVE_FILTER_CAPABILITIES structure.

*RssOrVmqPreference
A value that defines whether VMQ capabilities should be enabled instead of receive side scaling (RSS) capabilities.

This is a hidden keyword value that must not be specified in the INF file and is not displayed in Advanced property page for the network adapter. For more information, see Handling VMQ and RSS INF Keywords.

VMQ standardized INF keywords are enumeration keywords. The following table describes the possible INF entries for the VMQ standardized INF keywords.

The columns in this table describe the following attributes for an enumeration keyword:

SubkeyName
The name of the keyword that you must specify in the INF file. This name also appears in the registry under the NDI\params key for the network adapter.

ParamDesc
The display text that is associated with the SubkeyName INF entry.

Note The independent hardware vendor (IHV) can define any descriptive text for the SubkeyName.

Value
The enumeration integer value that is associated with each SubkeyName in the list.

EnumDesc
The display text that is associated with each value that appears in the Advanced property page.

For more information about standardized INF keywords, see Standardized INF Keywords for Network Devices.

Handling VMQ and RSS INF Keywords

Network adapters that support VMQ and receive side scaling (RSS) cannot use these features simultaneously. The operating system enables the use of the RSS or VMQ features in the following way:

• When the network adapter is bound to the TCP/IP stack, the operating enables the use of the RSS feature.

• When the network adapter is bound to the Hyper-V extensible switch driver stack, the operating system enables the use of the VMQ feature.

  For more information, see Hyper-V Extensible Switch.

Because the network adapter is not disabled and then re-enabled when it is unbound from the TCP/IP stack and bound to the Hyper-V driver stack (or the reverse), it is not possible for such network adapters to switch between VMQ and RSS automatically.

When NDIS calls the MiniportInitializeEx function, the miniport driver follows these steps before it reports its currently-enabled VMQ or RSS capabilities to NDIS:

1. The miniport driver reads the *RssOrVmqPreference keyword before reporting its currently-enabled capabilities to NDIS.

   If the value of the *RssOrVmqPreference keyword is 1, the miniport driver is configured for VMQ preference.

   If the value of the *RssOrVmqPreference keyword is zero or the keyword is not present, the miniport driver is configured for RSS preference.

2. If the miniport driver is configured for VMQ preference, it must read the *VMQ keyword to determine if VMQ is enabled on the network adapter. If the keyword is set to 1, the driver reports the currently-enabled VMQ settings. For more information on how the miniport driver reports VMQ settings, see Determining the VMQ Capabilities of a Network Adapter.

   For more information about the VMQ keywords, see Standardized INF Keywords for VMQ.

   Note If the miniport driver is configured for VMQ preference, it must not read any of the RSS standardized keywords.

3. If the miniport driver is configured for RSS preference, it must read the *RSS keyword to determine if RSS is enabled on the network adapter. If the keyword is set to 1, the driver reports the currently-enabled RSS settings. For more information on how the miniport driver reports RSS settings, see RSS Configuration.

   For more information about the RSS keywords, see Standardized INF Keywords for RSS.

   Note If the miniport driver is configured for RSS preference, it must not read any of the VMQ standardized keywords.

The following table describes how the miniport driver determines RSS or VMQ preference and advertises capabilities based on registry keywords:

Note The miniport driver must always report the complete RSS and VMQ hardware capabilities regardless of the values of these keywords. These keyword settings only affect how the driver reports the currently-enabled RSS and VMQ capabilities.

Reserved Registry Keywords

If the miniport driver supports VMQ and the VMQ interface is enabled on the network adapter, the driver must not read the following RSS INF entries:

The miniport driver that supports VMQ must not read the following subkeys under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\VMSMP\Parameters registry key.