307 lines
12 KiB
Plaintext
307 lines
12 KiB
Plaintext
Linux* Driver for Intel(R) Network Connection
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=============================================
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Intel Gigabit Linux driver.
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Copyright(c) 1999 - 2010 Intel Corporation.
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Contents
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========
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- Identifying Your Adapter
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- Command Line Parameters
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- Additional Configurations
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- Support
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Identifying Your Adapter
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========================
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The e1000e driver supports all PCI Express Intel(R) Gigabit Network
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Connections, except those that are 82575, 82576 and 82580-based*.
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* NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by
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the e1000 driver, not the e1000e driver due to the 82546 part being used
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behind a PCI Express bridge.
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For more information on how to identify your adapter, go to the Adapter &
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Driver ID Guide at:
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http://support.intel.com/support/go/network/adapter/idguide.htm
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For the latest Intel network drivers for Linux, refer to the following
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website. In the search field, enter your adapter name or type, or use the
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networking link on the left to search for your adapter:
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http://support.intel.com/support/go/network/adapter/home.htm
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Command Line Parameters
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=======================
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The default value for each parameter is generally the recommended setting,
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unless otherwise noted.
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NOTES: For more information about the InterruptThrottleRate,
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RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
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parameters, see the application note at:
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http://www.intel.com/design/network/applnots/ap450.htm
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InterruptThrottleRate
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---------------------
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Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
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4=simplified balancing)
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Default Value: 3
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The driver can limit the amount of interrupts per second that the adapter
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will generate for incoming packets. It does this by writing a value to the
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adapter that is based on the maximum amount of interrupts that the adapter
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will generate per second.
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Setting InterruptThrottleRate to a value greater or equal to 100
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will program the adapter to send out a maximum of that many interrupts
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per second, even if more packets have come in. This reduces interrupt
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load on the system and can lower CPU utilization under heavy load,
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but will increase latency as packets are not processed as quickly.
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The default behaviour of the driver previously assumed a static
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InterruptThrottleRate value of 8000, providing a good fallback value for
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all traffic types, but lacking in small packet performance and latency.
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The hardware can handle many more small packets per second however, and
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for this reason an adaptive interrupt moderation algorithm was implemented.
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The driver has two adaptive modes (setting 1 or 3) in which
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it dynamically adjusts the InterruptThrottleRate value based on the traffic
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that it receives. After determining the type of incoming traffic in the last
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timeframe, it will adjust the InterruptThrottleRate to an appropriate value
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for that traffic.
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The algorithm classifies the incoming traffic every interval into
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classes. Once the class is determined, the InterruptThrottleRate value is
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adjusted to suit that traffic type the best. There are three classes defined:
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"Bulk traffic", for large amounts of packets of normal size; "Low latency",
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for small amounts of traffic and/or a significant percentage of small
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packets; and "Lowest latency", for almost completely small packets or
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minimal traffic.
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In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
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for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
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latency" or "Lowest latency" class, the InterruptThrottleRate is increased
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stepwise to 20000. This default mode is suitable for most applications.
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For situations where low latency is vital such as cluster or
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grid computing, the algorithm can reduce latency even more when
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InterruptThrottleRate is set to mode 1. In this mode, which operates
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the same as mode 3, the InterruptThrottleRate will be increased stepwise to
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70000 for traffic in class "Lowest latency".
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In simplified mode the interrupt rate is based on the ratio of TX and
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RX traffic. If the bytes per second rate is approximately equal, the
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interrupt rate will drop as low as 2000 interrupts per second. If the
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traffic is mostly transmit or mostly receive, the interrupt rate could
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be as high as 8000.
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Setting InterruptThrottleRate to 0 turns off any interrupt moderation
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and may improve small packet latency, but is generally not suitable
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for bulk throughput traffic.
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NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
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RxAbsIntDelay parameters. In other words, minimizing the receive
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and/or transmit absolute delays does not force the controller to
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generate more interrupts than what the Interrupt Throttle Rate
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allows.
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NOTE: When e1000e is loaded with default settings and multiple adapters
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are in use simultaneously, the CPU utilization may increase non-
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linearly. In order to limit the CPU utilization without impacting
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the overall throughput, we recommend that you load the driver as
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follows:
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modprobe e1000e InterruptThrottleRate=3000,3000,3000
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This sets the InterruptThrottleRate to 3000 interrupts/sec for
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the first, second, and third instances of the driver. The range
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of 2000 to 3000 interrupts per second works on a majority of
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systems and is a good starting point, but the optimal value will
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be platform-specific. If CPU utilization is not a concern, use
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RX_POLLING (NAPI) and default driver settings.
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RxIntDelay
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----------
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Valid Range: 0-65535 (0=off)
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Default Value: 0
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This value delays the generation of receive interrupts in units of 1.024
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microseconds. Receive interrupt reduction can improve CPU efficiency if
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properly tuned for specific network traffic. Increasing this value adds
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extra latency to frame reception and can end up decreasing the throughput
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of TCP traffic. If the system is reporting dropped receives, this value
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may be set too high, causing the driver to run out of available receive
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descriptors.
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CAUTION: When setting RxIntDelay to a value other than 0, adapters may
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hang (stop transmitting) under certain network conditions. If
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this occurs a NETDEV WATCHDOG message is logged in the system
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event log. In addition, the controller is automatically reset,
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restoring the network connection. To eliminate the potential
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for the hang ensure that RxIntDelay is set to 0.
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RxAbsIntDelay
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-------------
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Valid Range: 0-65535 (0=off)
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Default Value: 8
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This value, in units of 1.024 microseconds, limits the delay in which a
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receive interrupt is generated. Useful only if RxIntDelay is non-zero,
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this value ensures that an interrupt is generated after the initial
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packet is received within the set amount of time. Proper tuning,
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along with RxIntDelay, may improve traffic throughput in specific network
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conditions.
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TxIntDelay
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----------
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Valid Range: 0-65535 (0=off)
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Default Value: 8
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This value delays the generation of transmit interrupts in units of
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1.024 microseconds. Transmit interrupt reduction can improve CPU
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efficiency if properly tuned for specific network traffic. If the
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system is reporting dropped transmits, this value may be set too high
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causing the driver to run out of available transmit descriptors.
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TxAbsIntDelay
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-------------
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Valid Range: 0-65535 (0=off)
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Default Value: 32
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This value, in units of 1.024 microseconds, limits the delay in which a
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transmit interrupt is generated. Useful only if TxIntDelay is non-zero,
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this value ensures that an interrupt is generated after the initial
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packet is sent on the wire within the set amount of time. Proper tuning,
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along with TxIntDelay, may improve traffic throughput in specific
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network conditions.
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Copybreak
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---------
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Valid Range: 0-xxxxxxx (0=off)
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Default Value: 256
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Driver copies all packets below or equaling this size to a fresh RX
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buffer before handing it up the stack.
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This parameter is different than other parameters, in that it is a
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single (not 1,1,1 etc.) parameter applied to all driver instances and
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it is also available during runtime at
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/sys/module/e1000e/parameters/copybreak
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SmartPowerDownEnable
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--------------------
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Valid Range: 0-1
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Default Value: 0 (disabled)
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Allows PHY to turn off in lower power states. The user can set this parameter
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in supported chipsets.
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KumeranLockLoss
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---------------
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Valid Range: 0-1
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Default Value: 1 (enabled)
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This workaround skips resetting the PHY at shutdown for the initial
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silicon releases of ICH8 systems.
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IntMode
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-------
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Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X)
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Default Value: 2
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Allows changing the interrupt mode at module load time, without requiring a
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recompile. If the driver load fails to enable a specific interrupt mode, the
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driver will try other interrupt modes, from least to most compatible. The
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interrupt order is MSI-X, MSI, Legacy. If specifying MSI (IntMode=1)
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interrupts, only MSI and Legacy will be attempted.
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CrcStripping
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------------
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Valid Range: 0-1
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Default Value: 1 (enabled)
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Strip the CRC from received packets before sending up the network stack. If
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you have a machine with a BMC enabled but cannot receive IPMI traffic after
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loading or enabling the driver, try disabling this feature.
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WriteProtectNVM
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---------------
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Valid Range: 0,1
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Default Value: 1
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If set to 1, configure the hardware to ignore all write/erase cycles to the
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GbE region in the ICHx NVM (in order to prevent accidental corruption of the
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NVM). This feature can be disabled by setting the parameter to 0 during initial
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driver load.
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NOTE: The machine must be power cycled (full off/on) when enabling NVM writes
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via setting the parameter to zero. Once the NVM has been locked (via the
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parameter at 1 when the driver loads) it cannot be unlocked except via power
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cycle.
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Additional Configurations
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=========================
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Jumbo Frames
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------------
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Jumbo Frames support is enabled by changing the MTU to a value larger than
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the default of 1500. Use the ifconfig command to increase the MTU size.
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For example:
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ifconfig eth<x> mtu 9000 up
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This setting is not saved across reboots.
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Notes:
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- The maximum MTU setting for Jumbo Frames is 9216. This value coincides
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with the maximum Jumbo Frames size of 9234 bytes.
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- Using Jumbo Frames at 10 or 100 Mbps is not supported and may result in
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poor performance or loss of link.
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- Some adapters limit Jumbo Frames sized packets to a maximum of
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4096 bytes and some adapters do not support Jumbo Frames.
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Ethtool
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-------
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The driver utilizes the ethtool interface for driver configuration and
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diagnostics, as well as displaying statistical information. We
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strongly recommend downloading the latest version of ethtool at:
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http://ftp.kernel.org/pub/software/network/ethtool/
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Speed and Duplex
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----------------
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Speed and Duplex are configured through the ethtool* utility. For
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instructions, refer to the ethtool man page.
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Enabling Wake on LAN* (WoL)
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---------------------------
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WoL is configured through the ethtool* utility. For instructions on
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enabling WoL with ethtool, refer to the ethtool man page.
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WoL will be enabled on the system during the next shut down or reboot.
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For this driver version, in order to enable WoL, the e1000e driver must be
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loaded when shutting down or rebooting the system.
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In most cases Wake On LAN is only supported on port A for multiple port
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adapters. To verify if a port supports Wake on Lan run ethtool eth<X>.
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Support
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=======
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For general information, go to the Intel support website at:
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www.intel.com/support/
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or the Intel Wired Networking project hosted by Sourceforge at:
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http://sourceforge.net/projects/e1000
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If an issue is identified with the released source code on the supported
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kernel with a supported adapter, email the specific information related
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to the issue to e1000-devel@lists.sf.net
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