Appendix A. NetKVM Driver Parameters After the NetKVM driver is installed, you can configure it to better suit your environment. The parameters listed in this section can be configured in the Windows Device Manager ( devmgmt.msc ). Important Modifying the driver's parameters causes Windows to reload that driver. This interrupts existing network activity. Procedure A.1. Configuring NetKVM Parameters Open Device Manager Click on the Start button. In the right-hand pane, right-click on Computer , and click Manage . If prompted, click Continue on the User Account Control window. This opens the Computer Management window. In the left-hand pane of the Computer Management window, click Device Manager . Locate the correct device In the central pane of the Computer Management window, click on the + symbol beside Network adapters . Under the list of Red Hat VirtIO Ethernet Adapter devices, double-click on NetKVM . This opens the Properties window for that device. View device parameters In the Properties window, click on the Advanced tab. Modify device parameters Click on the parameter you wish to modify to display the options for that parameter. Modify the options as appropriate, then click on OK to save your changes. A.1. Configurable Parameters for NetKVM Logging parameters Logging.Enable A Boolean value that determines whether logging is enabled. The default value is 1 (enabled). Logging.Level An integer that defines the logging level. As the integer increases, so does the verbosity of the log. The default value is 0 (errors only). 1-2 adds configuration messages. 3-4 adds packet flow information. 5-6 adds interrupt and DPC level trace information. Important High logging levels will slow down your guest virtual machine. Logging.Statistics(sec) An integer that defines whether log statistics are printed, and the time in seconds between each periodical statistics printout. The default value is 0 (no logging statistics). Initial parameters Assign MAC A string that defines the locally-administered MAC address for the paravirtualized NIC. This is not set by default. Init.ConnectionRate(Mb) An integer that represents the connection rate in megabytes. The default value for Windows 2008 and later is 10000 . Init.Do802.1PQ A Boolean value that enables Priority/VLAN tag population and removal support. The default value is 1 (enabled). Init.UseMergedBuffers A Boolean value that enables merge-able RX buffers. The default value is 1 (enabled). Init.UsePublishEvents A Boolean value that enables published event use. The default value is 1 (enabled). Init.MTUSize An integer that defines the maximum transmission unit (MTU). The default value is 1500 . Any value from 500 to 65500 is acceptable. Init.IndirectTx Controls whether indirect ring descriptors are in use. The default value is Disable , which disables use of indirect ring descriptors. Other valid values are Enable , which enables indirect ring descriptor usage; and Enable* , which enables conditional use of indirect ring descriptors. Init.MaxTxBuffers An integer that represents the amount of TX ring descriptors that will be allocated. The default value is 1024 . Valid values are: 16, 32, 64, 128, 256, 512, or 1024. Init.MaxRxBuffers An integer that represents the amount of RX ring descriptors that will be allocated. The default value is 256 . Valid values are: 16, 32, 64, 128, 256, 512, or 1024. Offload.Tx.Checksum Specifies the TX checksum offloading mode. In Red Hat Enterprise Linux 6.4 and onward, the valid values for this parameter are All (the default), which enables IP, TCP and UDP checksum offloading for both IPv4 and IPv6; TCP/UDP(v4,v6) , which enables TCP and UDP checksum offloading for both IPv4 and IPv6; TCP/UDP(v4) , which enables TCP and UDP checksum offloading for IPv4 only; and TCP(v4) , which enables only TCP checksum offloading for IPv4 only. In Red Hat Enterprise Linux 6.3 and earlier, the valid values for this parameter are TCP/UDP (the default value), which enables TCP and UDP checksum offload; TCP , which enables only TCP checksum offload; or Disable , which disables TX checksum offload. Offload.Tx.LSO A Boolean value that enables TX TCP Large Segment Offload (LSO). The default value is 1 (enabled). Offload.Rx.Checksum Specifies the RX checksum offloading mode. In Red Hat Enterprise Linux 6.4 and onward, the valid values for this parameter are All (the default), which enables IP, TCP and UDP checksum offloading for both IPv4 and IPv6; TCP/UDP(v4,v6) , which enables TCP and UDP checksum offloading for both IPv4 and IPv6; TCP/UDP(v4) , which enables TCP and UDP checksum offloading for IPv4 only; and TCP(v4) , which enables only TCP checksum offloading for IPv4 only. In Red Hat Enterprise Linux 6.3 and earlier, the valid values are Disable (the default), which disables RX checksum offloading; All , which enables TCP, UDP, and IP checksum offloading; TCP/UDP , which enables TCP and UDP checksum offloading; and TCP , which enables only TCP checksum offloading. Test and debug parameters Important Test and debug parameters should only be used for testing or debugging; they should not be used in production. TestOnly.DelayConnect(ms) The period for which to delay connection upon startup, in milliseconds. The default value is 0 . TestOnly.DPCChecking Sets the DPC checking mode. 0 (the default) disables DPC checking. 1 enables DPC checking; each hang test verifies DPC activity and acts as if the DPC was spawned. 2 clears the device interrupt status and is otherwise identical to 1 . TestOnly.Scatter-Gather A Boolean value that determines whether scatter-gather functionality is enabled. The default value is 1 (enabled). Setting this value to 0 disables scatter-gather functionality and all dependent capabilities. TestOnly.InterruptRecovery A Boolean value that determines whether interrupt recovery is enabled. The default value is 1 (enabled). TestOnly.PacketFilter A Boolean value that determines whether packet filtering is enabled. The default value is 1 (enabled). TestOnly.BatchReceive A Boolean value that determines whether packets are received in batches, or singularly. The default value is 1 , which enables batched packet receipt. TestOnly.Promiscuous A Boolean value that determines whether promiscuous mode is enabled. The default value is 0 (disabled). TestOnly.AnalyzeIPPackets A Boolean value that determines whether the checksum fields of outgoing IP packets are tested and verified for debugging purposes. The default value is 0 (no checking). TestOnly.RXThrottle An integer that determines the number of receive packets handled in a single DPC. The default value is 1000 . TestOnly.UseSwTxChecksum A Boolean value that determines whether hardware checksumming is enabled. The default value is 0 (disabled).

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