461 lines
18 KiB
Text
461 lines
18 KiB
Text
Linux* Base Driver for Intel(R) Ethernet Network Connection
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===========================================================
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Intel Gigabit Linux driver.
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Copyright(c) 1999 - 2013 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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- Speed and Duplex Configuration
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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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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 AutoNeg, Duplex, and Speed
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parameters, see the "Speed and Duplex Configuration" section in
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this document.
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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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AutoNeg
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-------
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(Supported only on adapters with copper connections)
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Valid Range: 0x01-0x0F, 0x20-0x2F
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Default Value: 0x2F
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This parameter is a bit-mask that specifies the speed and duplex settings
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advertised by the adapter. When this parameter is used, the Speed and
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Duplex parameters must not be specified.
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NOTE: Refer to the Speed and Duplex section of this readme for more
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information on the AutoNeg parameter.
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Duplex
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------
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(Supported only on adapters with copper connections)
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Valid Range: 0-2 (0=auto-negotiate, 1=half, 2=full)
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Default Value: 0
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This defines the direction in which data is allowed to flow. Can be
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either one or two-directional. If both Duplex and the link partner are
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set to auto-negotiate, the board auto-detects the correct duplex. If the
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link partner is forced (either full or half), Duplex defaults to half-
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duplex.
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FlowControl
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-----------
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Valid Range: 0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx)
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Default Value: Reads flow control settings from the EEPROM
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This parameter controls the automatic generation(Tx) and response(Rx)
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to Ethernet PAUSE frames.
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InterruptThrottleRate
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---------------------
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(not supported on Intel(R) 82542, 82543 or 82544-based adapters)
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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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Since 7.3.x, 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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CAUTION: If you are using the Intel(R) PRO/1000 CT Network Connection
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(controller 82547), setting InterruptThrottleRate to a value
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greater than 75,000, may hang (stop transmitting) adapters
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under certain network conditions. If this occurs a NETDEV
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WATCHDOG message is logged in the system event log. In
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addition, the controller is automatically reset, restoring
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the network connection. To eliminate the potential for the
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hang, ensure that InterruptThrottleRate is set no greater
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than 75,000 and is not set to 0.
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NOTE: When e1000 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 e1000 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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RxDescriptors
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-------------
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Valid Range: 80-256 for 82542 and 82543-based adapters
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80-4096 for all other supported adapters
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Default Value: 256
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This value specifies the number of receive buffer descriptors allocated
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by the driver. Increasing this value allows the driver to buffer more
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incoming packets, at the expense of increased system memory utilization.
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Each descriptor is 16 bytes. A receive buffer is also allocated for each
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descriptor and can be either 2048, 4096, 8192, or 16384 bytes, depending
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on the MTU setting. The maximum MTU size is 16110.
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NOTE: MTU designates the frame size. It only needs to be set for Jumbo
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Frames. Depending on the available system resources, the request
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for a higher number of receive descriptors may be denied. In this
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case, use a lower number.
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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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(This parameter is supported only on 82540, 82545 and later adapters.)
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Valid Range: 0-65535 (0=off)
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Default Value: 128
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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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Speed
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-----
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(This parameter is supported only on adapters with copper connections.)
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Valid Settings: 0, 10, 100, 1000
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Default Value: 0 (auto-negotiate at all supported speeds)
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Speed forces the line speed to the specified value in megabits per second
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(Mbps). If this parameter is not specified or is set to 0 and the link
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partner is set to auto-negotiate, the board will auto-detect the correct
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speed. Duplex should also be set when Speed is set to either 10 or 100.
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TxDescriptors
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-------------
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Valid Range: 80-256 for 82542 and 82543-based adapters
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80-4096 for all other supported adapters
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Default Value: 256
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This value is the number of transmit descriptors allocated by the driver.
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Increasing this value allows the driver to queue more transmits. Each
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descriptor is 16 bytes.
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NOTE: Depending on the available system resources, the request for a
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higher number of transmit descriptors may be denied. In this case,
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use a lower number.
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TxDescriptorStep
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----------------
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Valid Range: 1 (use every Tx Descriptor)
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4 (use every 4th Tx Descriptor)
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Default Value: 1 (use every Tx Descriptor)
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On certain non-Intel architectures, it has been observed that intense TX
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traffic bursts of short packets may result in an improper descriptor
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writeback. If this occurs, the driver will report a "TX Timeout" and reset
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the adapter, after which the transmit flow will restart, though data may
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have stalled for as much as 10 seconds before it resumes.
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The improper writeback does not occur on the first descriptor in a system
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memory cache-line, which is typically 32 bytes, or 4 descriptors long.
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Setting TxDescriptorStep to a value of 4 will ensure that all TX descriptors
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are aligned to the start of a system memory cache line, and so this problem
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will not occur.
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NOTES: Setting TxDescriptorStep to 4 effectively reduces the number of
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TxDescriptors available for transmits to 1/4 of the normal allocation.
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This has a possible negative performance impact, which may be
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compensated for by allocating more descriptors using the TxDescriptors
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module parameter.
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There are other conditions which may result in "TX Timeout", which will
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not be resolved by the use of the TxDescriptorStep parameter. As the
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issue addressed by this parameter has never been observed on Intel
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Architecture platforms, it should not be used on Intel platforms.
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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: 64
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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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(This parameter is supported only on 82540, 82545 and later adapters.)
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Valid Range: 0-65535 (0=off)
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Default Value: 64
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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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XsumRX
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------
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(This parameter is NOT supported on the 82542-based adapter.)
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Valid Range: 0-1
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Default Value: 1
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A value of '1' indicates that the driver should enable IP checksum
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offload for received packets (both UDP and TCP) to the adapter hardware.
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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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Usage: insmod e1000.ko copybreak=128
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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/e1000/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 turn off
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this parameter 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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Speed and Duplex Configuration
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==============================
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Three keywords are used to control the speed and duplex configuration.
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These keywords are Speed, Duplex, and AutoNeg.
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If the board uses a fiber interface, these keywords are ignored, and the
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fiber interface board only links at 1000 Mbps full-duplex.
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For copper-based boards, the keywords interact as follows:
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The default operation is auto-negotiate. The board advertises all
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supported speed and duplex combinations, and it links at the highest
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common speed and duplex mode IF the link partner is set to auto-negotiate.
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If Speed = 1000, limited auto-negotiation is enabled and only 1000 Mbps
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is advertised (The 1000BaseT spec requires auto-negotiation.)
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If Speed = 10 or 100, then both Speed and Duplex should be set. Auto-
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negotiation is disabled, and the AutoNeg parameter is ignored. Partner
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SHOULD also be forced.
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The AutoNeg parameter is used when more control is required over the
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auto-negotiation process. It should be used when you wish to control which
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speed and duplex combinations are advertised during the auto-negotiation
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process.
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The parameter may be specified as either a decimal or hexadecimal value as
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determined by the bitmap below.
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Bit position 7 6 5 4 3 2 1 0
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Decimal Value 128 64 32 16 8 4 2 1
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Hex value 80 40 20 10 8 4 2 1
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Speed (Mbps) N/A N/A 1000 N/A 100 100 10 10
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Duplex Full Full Half Full Half
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Some examples of using AutoNeg:
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modprobe e1000 AutoNeg=0x01 (Restricts autonegotiation to 10 Half)
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modprobe e1000 AutoNeg=1 (Same as above)
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modprobe e1000 AutoNeg=0x02 (Restricts autonegotiation to 10 Full)
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modprobe e1000 AutoNeg=0x03 (Restricts autonegotiation to 10 Half or 10 Full)
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modprobe e1000 AutoNeg=0x04 (Restricts autonegotiation to 100 Half)
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modprobe e1000 AutoNeg=0x05 (Restricts autonegotiation to 10 Half or 100
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Half)
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modprobe e1000 AutoNeg=0x020 (Restricts autonegotiation to 1000 Full)
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modprobe e1000 AutoNeg=32 (Same as above)
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Note that when this parameter is used, Speed and Duplex must not be specified.
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If the link partner is forced to a specific speed and duplex, then this
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parameter should not be used. Instead, use the Speed and Duplex parameters
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previously mentioned to force the adapter to the same speed and duplex.
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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. It can be made permanent if
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you add:
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MTU=9000
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to the file /etc/sysconfig/network-scripts/ifcfg-eth<x>. This example
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applies to the Red Hat distributions; other distributions may store this
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setting in a different location.
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Notes:
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Degradation in throughput performance may be observed in some Jumbo frames
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environments. If this is observed, increasing the application's socket buffer
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size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values may help.
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See the specific application manual and /usr/src/linux*/Documentation/
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networking/ip-sysctl.txt for more details.
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- The maximum MTU setting for Jumbo Frames is 16110. This value coincides
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with the maximum Jumbo Frames size of 16128.
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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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- Adapters based on the Intel(R) 82542 and 82573V/E controller do not
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support Jumbo Frames. These correspond to the following product names:
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Intel(R) PRO/1000 Gigabit Server Adapter
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Intel(R) PRO/1000 PM Network Connection
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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. The ethtool
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version 1.6 or later is required for this functionality.
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The latest release of ethtool can be found from
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http://ftp.kernel.org/pub/software/network/ethtool/
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Enabling Wake on LAN* (WoL)
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---------------------------
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WoL is configured through the ethtool* utility.
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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 e1000 driver must be
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loaded when shutting down or rebooting the system.
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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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http://support.intel.com
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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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