Documentation/networking/e1000e.txt - arm/linux - Git at Google

 Linux* Driver for Intel(R) Ethernet Network Connection
 ======================================================

 Intel Gigabit Linux driver.
 Copyright(c) 1999 - 2013 Intel Corporation.

 Contents
 ========

 - Identifying Your Adapter
 - Command Line Parameters
 - Additional Configurations
 - Support

 Identifying Your Adapter
 ========================

 The e1000e driver supports all PCI Express Intel(R) Gigabit Network
 Connections, except those that are 82575, 82576 and 82580-based*.

 * NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by
   the e1000 driver, not the e1000e driver due to the 82546 part being used
   behind a PCI Express bridge.

 For more information on how to identify your adapter, go to the Adapter &
 Driver ID Guide at:

     http://support.intel.com/support/go/network/adapter/idguide.htm

 For the latest Intel network drivers for Linux, refer to the following
 website.  In the search field, enter your adapter name or type, or use the
 networking link on the left to search for your adapter:

     http://support.intel.com/support/go/network/adapter/home.htm

 Command Line Parameters
 =======================

 The default value for each parameter is generally the recommended setting,
 unless otherwise noted.

 NOTES:  For more information about the InterruptThrottleRate,
         RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
         parameters, see the application note at:
         http://www.intel.com/design/network/applnots/ap450.htm

 InterruptThrottleRate
 ---------------------
 Valid Range:   0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
                                    4=simplified balancing)
 Default Value: 3

 The driver can limit the amount of interrupts per second that the adapter
 will generate for incoming packets. It does this by writing a value to the
 adapter that is based on the maximum amount of interrupts that the adapter
 will generate per second.

 Setting InterruptThrottleRate to a value greater or equal to 100
 will program the adapter to send out a maximum of that many interrupts
 per second, even if more packets have come in. This reduces interrupt
 load on the system and can lower CPU utilization under heavy load,
 but will increase latency as packets are not processed as quickly.

 The default behaviour of the driver previously assumed a static
 InterruptThrottleRate value of 8000, providing a good fallback value for
 all traffic types, but lacking in small packet performance and latency.
 The hardware can handle many more small packets per second however, and
 for this reason an adaptive interrupt moderation algorithm was implemented.

 The driver has two adaptive modes (setting 1 or 3) in which
 it dynamically adjusts the InterruptThrottleRate value based on the traffic
 that it receives. After determining the type of incoming traffic in the last
 timeframe, it will adjust the InterruptThrottleRate to an appropriate value
 for that traffic.

 The algorithm classifies the incoming traffic every interval into
 classes.  Once the class is determined, the InterruptThrottleRate value is
 adjusted to suit that traffic type the best. There are three classes defined:
 "Bulk traffic", for large amounts of packets of normal size; "Low latency",
 for small amounts of traffic and/or a significant percentage of small
 packets; and "Lowest latency", for almost completely small packets or
 minimal traffic.

 In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
 for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
 latency" or "Lowest latency" class, the InterruptThrottleRate is increased
 stepwise to 20000. This default mode is suitable for most applications.

 For situations where low latency is vital such as cluster or
 grid computing, the algorithm can reduce latency even more when
 InterruptThrottleRate is set to mode 1. In this mode, which operates
 the same as mode 3, the InterruptThrottleRate will be increased stepwise to
 70000 for traffic in class "Lowest latency".

 In simplified mode the interrupt rate is based on the ratio of TX and
 RX traffic.  If the bytes per second rate is approximately equal, the
 interrupt rate will drop as low as 2000 interrupts per second.  If the
 traffic is mostly transmit or mostly receive, the interrupt rate could
 be as high as 8000.

 Setting InterruptThrottleRate to 0 turns off any interrupt moderation
 and may improve small packet latency, but is generally not suitable
 for bulk throughput traffic.

 NOTE:  InterruptThrottleRate takes precedence over the TxAbsIntDelay and
        RxAbsIntDelay parameters.  In other words, minimizing the receive
        and/or transmit absolute delays does not force the controller to
        generate more interrupts than what the Interrupt Throttle Rate
        allows.

 NOTE:  When e1000e is loaded with default settings and multiple adapters
        are in use simultaneously, the CPU utilization may increase non-
        linearly.  In order to limit the CPU utilization without impacting
        the overall throughput, we recommend that you load the driver as
        follows:

            modprobe e1000e InterruptThrottleRate=3000,3000,3000

        This sets the InterruptThrottleRate to 3000 interrupts/sec for
        the first, second, and third instances of the driver.  The range
        of 2000 to 3000 interrupts per second works on a majority of
        systems and is a good starting point, but the optimal value will
        be platform-specific.  If CPU utilization is not a concern, use
        RX_POLLING (NAPI) and default driver settings.

 RxIntDelay
 ----------
 Valid Range:   0-65535 (0=off)
 Default Value: 0

 This value delays the generation of receive interrupts in units of 1.024
 microseconds.  Receive interrupt reduction can improve CPU efficiency if
 properly tuned for specific network traffic.  Increasing this value adds
 extra latency to frame reception and can end up decreasing the throughput
 of TCP traffic.  If the system is reporting dropped receives, this value
 may be set too high, causing the driver to run out of available receive
 descriptors.

 CAUTION:  When setting RxIntDelay to a value other than 0, adapters may
           hang (stop transmitting) under certain network conditions.  If
           this occurs a NETDEV WATCHDOG message is logged in the system
           event log.  In addition, the controller is automatically reset,
           restoring the network connection.  To eliminate the potential
           for the hang ensure that RxIntDelay is set to 0.

 RxAbsIntDelay
 -------------
 Valid Range:   0-65535 (0=off)
 Default Value: 8

 This value, in units of 1.024 microseconds, limits the delay in which a
 receive interrupt is generated.  Useful only if RxIntDelay is non-zero,
 this value ensures that an interrupt is generated after the initial
 packet is received within the set amount of time.  Proper tuning,
 along with RxIntDelay, may improve traffic throughput in specific network
 conditions.

 TxIntDelay
 ----------
 Valid Range:   0-65535 (0=off)
 Default Value: 8

 This value delays the generation of transmit interrupts in units of
 1.024 microseconds.  Transmit interrupt reduction can improve CPU
 efficiency if properly tuned for specific network traffic.  If the
 system is reporting dropped transmits, this value may be set too high
 causing the driver to run out of available transmit descriptors.

 TxAbsIntDelay
 -------------
 Valid Range:   0-65535 (0=off)
 Default Value: 32

 This value, in units of 1.024 microseconds, limits the delay in which a
 transmit interrupt is generated.  Useful only if TxIntDelay is non-zero,
 this value ensures that an interrupt is generated after the initial
 packet is sent on the wire within the set amount of time.  Proper tuning,
 along with TxIntDelay, may improve traffic throughput in specific
 network conditions.

 Copybreak
 ---------
 Valid Range:   0-xxxxxxx (0=off)
 Default Value: 256

 Driver copies all packets below or equaling this size to a fresh RX
 buffer before handing it up the stack.

 This parameter is different than other parameters, in that it is a
 single (not 1,1,1 etc.) parameter applied to all driver instances and
 it is also available during runtime at
 /sys/module/e1000e/parameters/copybreak

 SmartPowerDownEnable
 --------------------
 Valid Range: 0-1
 Default Value:  0 (disabled)

 Allows PHY to turn off in lower power states. The user can set this parameter
 in supported chipsets.

 KumeranLockLoss
 ---------------
 Valid Range: 0-1
 Default Value: 1 (enabled)

 This workaround skips resetting the PHY at shutdown for the initial
 silicon releases of ICH8 systems.

 IntMode
 -------
 Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X)
 Default Value: 2

 Allows changing the interrupt mode at module load time, without requiring a
 recompile. If the driver load fails to enable a specific interrupt mode, the
 driver will try other interrupt modes, from least to most compatible.  The
 interrupt order is MSI-X, MSI, Legacy.  If specifying MSI (IntMode=1)
 interrupts, only MSI and Legacy will be attempted.

 CrcStripping
 ------------
 Valid Range: 0-1
 Default Value: 1 (enabled)

 Strip the CRC from received packets before sending up the network stack.  If
 you have a machine with a BMC enabled but cannot receive IPMI traffic after
 loading or enabling the driver, try disabling this feature.

 WriteProtectNVM
 ---------------
 Valid Range: 0,1
 Default Value: 1

 If set to 1, configure the hardware to ignore all write/erase cycles to the
 GbE region in the ICHx NVM (in order to prevent accidental corruption of the
 NVM). This feature can be disabled by setting the parameter to 0 during initial
 driver load.
 NOTE: The machine must be power cycled (full off/on) when enabling NVM writes
 via setting the parameter to zero. Once the NVM has been locked (via the
 parameter at 1 when the driver loads) it cannot be unlocked except via power
 cycle.

 Additional Configurations
 =========================

   Jumbo Frames
   ------------
   Jumbo Frames support is enabled by changing the MTU to a value larger than
   the default of 1500.  Use the ifconfig command to increase the MTU size.
   For example:

        ifconfig eth<x> mtu 9000 up

   This setting is not saved across reboots.

   Notes:

   - The maximum MTU setting for Jumbo Frames is 9216.  This value coincides
     with the maximum Jumbo Frames size of 9234 bytes.

   - Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
     poor performance or loss of link.

   - Some adapters limit Jumbo Frames sized packets to a maximum of
     4096 bytes and some adapters do not support Jumbo Frames.

   - Jumbo Frames cannot be configured on an 82579-based Network device, if
     MACSec is enabled on the system.

   ethtool
   -------
   The driver utilizes the ethtool interface for driver configuration and
   diagnostics, as well as displaying statistical information.  We
   strongly recommend downloading the latest version of ethtool at:

   https://kernel.org/pub/software/network/ethtool/

   NOTE: When validating enable/disable tests on some parts (82578, for example)
   you need to add a few seconds between tests when working with ethtool.

   Speed and Duplex
   ----------------
   Speed and Duplex are configured through the ethtool* utility. For
   instructions,  refer to the ethtool man page.

   Enabling Wake on LAN* (WoL)
   ---------------------------
   WoL is configured through the ethtool* utility. For instructions on
   enabling WoL with ethtool, refer to the ethtool man page.

   WoL will be enabled on the system during the next shut down or reboot.
   For this driver version, in order to enable WoL, the e1000e driver must be
   loaded when shutting down or rebooting the system.

   In most cases Wake On LAN is only supported on port A for multiple port
   adapters. To verify if a port supports Wake on Lan run ethtool eth<X>.

 Support
 =======

 For general information, go to the Intel support website at:

     www.intel.com/support/

 or the Intel Wired Networking project hosted by Sourceforge at:

     http://sourceforge.net/projects/e1000

 If an issue is identified with the released source code on the supported
 kernel with a supported adapter, email the specific information related
 to the issue to e1000-devel@lists.sf.net
	Linux* Driver for Intel(R) Ethernet Network Connection
	======================================================

	Intel Gigabit Linux driver.
	Copyright(c) 1999 - 2013 Intel Corporation.

	Contents
	========

	- Identifying Your Adapter
	- Command Line Parameters
	- Additional Configurations
	- Support

	Identifying Your Adapter
	========================

	The e1000e driver supports all PCI Express Intel(R) Gigabit Network
	Connections, except those that are 82575, 82576 and 82580-based*.

	* NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by
	the e1000 driver, not the e1000e driver due to the 82546 part being used
	behind a PCI Express bridge.

	For more information on how to identify your adapter, go to the Adapter &
	Driver ID Guide at:

	http://support.intel.com/support/go/network/adapter/idguide.htm

	For the latest Intel network drivers for Linux, refer to the following
	website. In the search field, enter your adapter name or type, or use the
	networking link on the left to search for your adapter:

	http://support.intel.com/support/go/network/adapter/home.htm

	Command Line Parameters
	=======================

	The default value for each parameter is generally the recommended setting,
	unless otherwise noted.

	NOTES: For more information about the InterruptThrottleRate,
	RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
	parameters, see the application note at:
	http://www.intel.com/design/network/applnots/ap450.htm

	InterruptThrottleRate
	---------------------
	Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
	4=simplified balancing)
	Default Value: 3

	The driver can limit the amount of interrupts per second that the adapter
	will generate for incoming packets. It does this by writing a value to the
	adapter that is based on the maximum amount of interrupts that the adapter
	will generate per second.

	Setting InterruptThrottleRate to a value greater or equal to 100
	will program the adapter to send out a maximum of that many interrupts
	per second, even if more packets have come in. This reduces interrupt
	load on the system and can lower CPU utilization under heavy load,
	but will increase latency as packets are not processed as quickly.

	The default behaviour of the driver previously assumed a static
	InterruptThrottleRate value of 8000, providing a good fallback value for
	all traffic types, but lacking in small packet performance and latency.
	The hardware can handle many more small packets per second however, and
	for this reason an adaptive interrupt moderation algorithm was implemented.

	The driver has two adaptive modes (setting 1 or 3) in which
	it dynamically adjusts the InterruptThrottleRate value based on the traffic
	that it receives. After determining the type of incoming traffic in the last
	timeframe, it will adjust the InterruptThrottleRate to an appropriate value
	for that traffic.

	The algorithm classifies the incoming traffic every interval into
	classes. Once the class is determined, the InterruptThrottleRate value is
	adjusted to suit that traffic type the best. There are three classes defined:
	"Bulk traffic", for large amounts of packets of normal size; "Low latency",
	for small amounts of traffic and/or a significant percentage of small
	packets; and "Lowest latency", for almost completely small packets or
	minimal traffic.

	In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
	for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
	latency" or "Lowest latency" class, the InterruptThrottleRate is increased
	stepwise to 20000. This default mode is suitable for most applications.

	For situations where low latency is vital such as cluster or
	grid computing, the algorithm can reduce latency even more when
	InterruptThrottleRate is set to mode 1. In this mode, which operates
	the same as mode 3, the InterruptThrottleRate will be increased stepwise to
	70000 for traffic in class "Lowest latency".

	In simplified mode the interrupt rate is based on the ratio of TX and
	RX traffic. If the bytes per second rate is approximately equal, the
	interrupt rate will drop as low as 2000 interrupts per second. If the
	traffic is mostly transmit or mostly receive, the interrupt rate could
	be as high as 8000.

	Setting InterruptThrottleRate to 0 turns off any interrupt moderation
	and may improve small packet latency, but is generally not suitable
	for bulk throughput traffic.

	NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
	RxAbsIntDelay parameters. In other words, minimizing the receive
	and/or transmit absolute delays does not force the controller to
	generate more interrupts than what the Interrupt Throttle Rate
	allows.

	NOTE: When e1000e is loaded with default settings and multiple adapters
	are in use simultaneously, the CPU utilization may increase non-
	linearly. In order to limit the CPU utilization without impacting
	the overall throughput, we recommend that you load the driver as
	follows:

	modprobe e1000e InterruptThrottleRate=3000,3000,3000

	This sets the InterruptThrottleRate to 3000 interrupts/sec for
	the first, second, and third instances of the driver. The range
	of 2000 to 3000 interrupts per second works on a majority of
	systems and is a good starting point, but the optimal value will
	be platform-specific. If CPU utilization is not a concern, use
	RX_POLLING (NAPI) and default driver settings.

	RxIntDelay
	----------
	Valid Range: 0-65535 (0=off)
	Default Value: 0

	This value delays the generation of receive interrupts in units of 1.024
	microseconds. Receive interrupt reduction can improve CPU efficiency if
	properly tuned for specific network traffic. Increasing this value adds
	extra latency to frame reception and can end up decreasing the throughput
	of TCP traffic. If the system is reporting dropped receives, this value
	may be set too high, causing the driver to run out of available receive
	descriptors.

	CAUTION: When setting RxIntDelay to a value other than 0, adapters may
	hang (stop transmitting) under certain network conditions. If
	this occurs a NETDEV WATCHDOG message is logged in the system
	event log. In addition, the controller is automatically reset,
	restoring the network connection. To eliminate the potential
	for the hang ensure that RxIntDelay is set to 0.

	RxAbsIntDelay
	-------------
	Valid Range: 0-65535 (0=off)
	Default Value: 8

	This value, in units of 1.024 microseconds, limits the delay in which a
	receive interrupt is generated. Useful only if RxIntDelay is non-zero,
	this value ensures that an interrupt is generated after the initial
	packet is received within the set amount of time. Proper tuning,
	along with RxIntDelay, may improve traffic throughput in specific network
	conditions.

	TxIntDelay
	----------
	Valid Range: 0-65535 (0=off)
	Default Value: 8

	This value delays the generation of transmit interrupts in units of
	1.024 microseconds. Transmit interrupt reduction can improve CPU
	efficiency if properly tuned for specific network traffic. If the
	system is reporting dropped transmits, this value may be set too high
	causing the driver to run out of available transmit descriptors.

	TxAbsIntDelay
	-------------
	Valid Range: 0-65535 (0=off)
	Default Value: 32

	This value, in units of 1.024 microseconds, limits the delay in which a
	transmit interrupt is generated. Useful only if TxIntDelay is non-zero,
	this value ensures that an interrupt is generated after the initial
	packet is sent on the wire within the set amount of time. Proper tuning,
	along with TxIntDelay, may improve traffic throughput in specific
	network conditions.

	Copybreak
	---------
	Valid Range: 0-xxxxxxx (0=off)
	Default Value: 256

	Driver copies all packets below or equaling this size to a fresh RX
	buffer before handing it up the stack.

	This parameter is different than other parameters, in that it is a
	single (not 1,1,1 etc.) parameter applied to all driver instances and
	it is also available during runtime at
	/sys/module/e1000e/parameters/copybreak

	SmartPowerDownEnable
	--------------------
	Valid Range: 0-1
	Default Value: 0 (disabled)

	Allows PHY to turn off in lower power states. The user can set this parameter
	in supported chipsets.

	KumeranLockLoss
	---------------
	Valid Range: 0-1
	Default Value: 1 (enabled)

	This workaround skips resetting the PHY at shutdown for the initial
	silicon releases of ICH8 systems.

	IntMode
	-------
	Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X)
	Default Value: 2

	Allows changing the interrupt mode at module load time, without requiring a
	recompile. If the driver load fails to enable a specific interrupt mode, the
	driver will try other interrupt modes, from least to most compatible. The
	interrupt order is MSI-X, MSI, Legacy. If specifying MSI (IntMode=1)
	interrupts, only MSI and Legacy will be attempted.

	CrcStripping
	------------
	Valid Range: 0-1
	Default Value: 1 (enabled)

	Strip the CRC from received packets before sending up the network stack. If
	you have a machine with a BMC enabled but cannot receive IPMI traffic after
	loading or enabling the driver, try disabling this feature.

	WriteProtectNVM
	---------------
	Valid Range: 0,1
	Default Value: 1

	If set to 1, configure the hardware to ignore all write/erase cycles to the
	GbE region in the ICHx NVM (in order to prevent accidental corruption of the
	NVM). This feature can be disabled by setting the parameter to 0 during initial
	driver load.
	NOTE: The machine must be power cycled (full off/on) when enabling NVM writes
	via setting the parameter to zero. Once the NVM has been locked (via the
	parameter at 1 when the driver loads) it cannot be unlocked except via power
	cycle.

	Additional Configurations
	=========================

	Jumbo Frames
	------------
	Jumbo Frames support is enabled by changing the MTU to a value larger than
	the default of 1500. Use the ifconfig command to increase the MTU size.
	For example:

	ifconfig eth<x> mtu 9000 up

	This setting is not saved across reboots.

	Notes:

	- The maximum MTU setting for Jumbo Frames is 9216. This value coincides
	with the maximum Jumbo Frames size of 9234 bytes.

	- Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
	poor performance or loss of link.

	- Some adapters limit Jumbo Frames sized packets to a maximum of
	4096 bytes and some adapters do not support Jumbo Frames.

	- Jumbo Frames cannot be configured on an 82579-based Network device, if
	MACSec is enabled on the system.

	ethtool
	-------
	The driver utilizes the ethtool interface for driver configuration and
	diagnostics, as well as displaying statistical information. We
	strongly recommend downloading the latest version of ethtool at:

	https://kernel.org/pub/software/network/ethtool/

	NOTE: When validating enable/disable tests on some parts (82578, for example)
	you need to add a few seconds between tests when working with ethtool.

	Speed and Duplex
	----------------
	Speed and Duplex are configured through the ethtool* utility. For
	instructions, refer to the ethtool man page.

	Enabling Wake on LAN* (WoL)
	---------------------------
	WoL is configured through the ethtool* utility. For instructions on
	enabling WoL with ethtool, refer to the ethtool man page.

	WoL will be enabled on the system during the next shut down or reboot.
	For this driver version, in order to enable WoL, the e1000e driver must be
	loaded when shutting down or rebooting the system.

	In most cases Wake On LAN is only supported on port A for multiple port
	adapters. To verify if a port supports Wake on Lan run ethtool eth<X>.

	Support
	=======

	For general information, go to the Intel support website at:

	www.intel.com/support/

	or the Intel Wired Networking project hosted by Sourceforge at:

	http://sourceforge.net/projects/e1000

	If an issue is identified with the released source code on the supported
	kernel with a supported adapter, email the specific information related
	to the issue to e1000-devel@lists.sf.net