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EM(4)			     Kernel Interfaces Manual			   EM(4)

NAME
     em -- Intel(R) PRO/1000 Gigabit Ethernet adapter driver

SYNOPSIS
     To compile this driver into the kernel, place the following lines in your
     kernel configuration file:

	   device iflib
	   device em

     Alternatively, to load the driver as a module at boot time, place the
     following line in loader.conf(5):

	   if_em_load="YES"

DESCRIPTION
     The  em  driver provides support for PCI Gigabit Ethernet adapters based on
     the Intel 82540, 82541ER,	82541PI,  82542,  82543,  82544,  82545,  82546,
     82546EB, 82546GB, 82547, 82571, 81572, 82573, and 82574 Ethernet controller
     chips.

     The  em  driver  also  provides  support  for  PCI Express Gigabit Ethernet
     adapters based on the Intel 82575, 82576, 82580, i21x and i35x.

     The driver supports Transmit/Receive checksum offload and Jumbo  Frames  on
     all but 82542-based adapters.

     Furthermore  it supports TCP segmentation offload (TSO) on all adapters but
     those based on the 82543, 82544 and 82547 controller chips.  The  identifi-
     cation  LEDs  of  the adapters supported by the em driver can be controlled
     via the led(4) API for localization purposes.  For further hardware  infor-
     mation, see the README included with the driver.

     For  questions related to hardware requirements, refer to the documentation
     supplied with your  Intel	PRO/1000  adapter.   All  hardware  requirements
     listed apply to use with FreeBSD.

     Support  for  Jumbo  Frames is provided via the interface MTU setting.  Se-
     lecting an MTU larger than 1500 bytes with the ifconfig(8) utility  config-
     ures  the	adapter  to  receive and transmit Jumbo Frames.  The maximum MTU
     size for Jumbo Frames is 16114.

     This driver supports hardware assisted VLANs.  The em driver  supports  the
     following media types:

     autoselect   Enables auto-negotiation for speed and duplex.

     10baseT/UTP  Sets	10Mbps	operation.   Use  the  mediaopt option to select
		  full-duplex mode.

     100baseTX	  Sets 100Mbps operation.  Use the  mediaopt  option  to  select
		  full-duplex mode.

     1000baseSX   Sets	1000Mbps  operation.  Only full-duplex mode is supported
		  at this speed.

     1000baseTX   Sets 1000Mbps operation.  Only full-duplex mode  is  supported
		  at this speed.

     The em driver supports the following media options:

     full-duplex  Forces full-duplex operation

     half-duplex  Forces half-duplex operation.

     Only  use	mediaopt  to  set the driver to full-duplex.  If mediaopt is not
     specified, the driver defaults to half-duplex.

     For more information on configuring this device, see ifconfig(8).

HARDWARE
     The em driver supports Gigabit Ethernet adapters based on the Intel  82540,
     82541ER,  82541PI,  82542,  82543,  82544,  82545, 82546, 82546EB, 82546GB,
     82547, 82571, 82572, 82573,  82574,  82575,  82576,  and  82580  controller
     chips:

     *	 Intel Gigabit ET Dual Port Server Adapter (82576)
     *	 Intel Gigabit VT Quad Port Server Adapter (82575)
     *	 Intel Single, Dual and Quad Gigabit Ethernet Controller (82580)
     *	 Intel i210 and i211 Gigabit Ethernet Controller
     *	 Intel i350 and i354 Gigabit Ethernet Controller
     *	 Intel PRO/1000 CT Network Connection (82547)
     *	 Intel PRO/1000 F Server Adapter (82543)
     *	 Intel PRO/1000 Gigabit Server Adapter (82542)
     *	 Intel PRO/1000 GT Desktop Adapter (82541PI)
     *	 Intel PRO/1000 MF Dual Port Server Adapter (82546)
     *	 Intel PRO/1000 MF Server Adapter (82545)
     *	 Intel PRO/1000 MF Server Adapter (LX) (82545)
     *	 Intel PRO/1000 MT Desktop Adapter (82540)
     *	 Intel PRO/1000 MT Desktop Adapter (82541)
     *	 Intel PRO/1000 MT Dual Port Server Adapter (82546)
     *	 Intel PRO/1000 MT Quad Port Server Adapter (82546EB)
     *	 Intel PRO/1000 MT Server Adapter (82545)
     *	 Intel PRO/1000 PF Dual Port Server Adapter (82571)
     *	 Intel PRO/1000 PF Quad Port Server Adapter (82571)
     *	 Intel PRO/1000 PF Server Adapter (82572)
     *	 Intel PRO/1000 PT Desktop Adapter (82572)
     *	 Intel PRO/1000 PT Dual Port Server Adapter (82571)
     *	 Intel PRO/1000 PT Quad Port Server Adapter (82571)
     *	 Intel PRO/1000 PT Server Adapter (82572)
     *	 Intel PRO/1000 T Desktop Adapter (82544)
     *	 Intel PRO/1000 T Server Adapter (82543)
     *	 Intel PRO/1000 XF Server Adapter (82544)
     *	 Intel PRO/1000 XT Server Adapter (82544)

LOADER TUNABLES
     Tunables  can  be	set at the loader(8) prompt before booting the kernel or
     stored in loader.conf(5).

     hw.em.disable_crc_stripping
	     Disable or enable hardware stripping of CRC field.  This is  mostly
	     useful on BMC/IPMI shared interfaces where stripping the CRC causes
	     remote access over IPMI to fail.  Default 0 (enabled).

     hw.em.eee_setting
	     Disable or enable Energy Efficient Ethernet.  Default 1 (disabled).

     hw.em.msix
	     Enable or disable MSI-X style interrupts.	Default 1 (enabled).

     hw.em.smart_pwr_down
	     Enable or disable smart power down features on newer adapters.  De-
	     fault 0 (disabled).

     hw.em.sbp
	     Show bad packets when in promiscuous mode.  Default 0 (off).

     hw.em.rxd
	     Number of receive descriptors allocated by the driver.  The default
	     value  is	1024  for  adapters  newer than 82547, and 256 for older
	     ones.  The 82542 and 82543-based adapters can handle up to 256  de-
	     scriptors, while others can have up to 4096.

     hw.em.txd
	     Number  of  transmit  descriptors allocated by the driver.  The de-
	     fault value is 1024 for adapters newer  than  82547,  and	256  for
	     older  ones.   The  82542 and 82543-based adapters can handle up to
	     256 descriptors, while others can have up to 4096.

     hw.em.rx_int_delay
	     This value delays the generation of receive interrupts in units  of
	     1.024  microseconds.   The  default  value is 0, since adapters may
	     hang with this feature being enabled.

     hw.em.rx_abs_int_delay
	     If hw.em.rx_int_delay is non-zero, this tunable limits the  maximum
	     delay in which a receive interrupt is generated.

     hw.em.tx_int_delay
	     This value delays the generation of transmit interrupts in units of
	     1.024 microseconds.  The default value is 64.

     hw.em.tx_abs_int_delay
	     If  hw.em.tx_int_delay is non-zero, this tunable limits the maximum
	     delay in which a transmit interrupt is generated.

FILES
     /dev/led/em*  identification LED device nodes

EXAMPLES
     Make the identification LED of em0 blink:

	   echo f2 > /dev/led/em0

     Turn the identification LED of em0 off again:

	   echo 0 > /dev/led/em0

DIAGNOSTICS
     em%d: Unable to allocate bus resource: memory  A fatal initialization error
     has occurred.

     em%d: Unable to allocate bus resource: interrupt	A  fatal  initialization
     error has occurred.

     em%d:  watchdog  timeout -- resetting  The device has stopped responding to
     the network, or there is a problem with the network connection (cable).

SUPPORT
     For general information and support, go to the Intel  support  website  at:
     http://support.intel.com.

     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 <freebsd@intel.com>.

SEE ALSO
     altq(4),  arp(4),	iflib(4),  led(4), netintro(4), ng_ether(4), polling(4),
     vlan(4), ifconfig(8)

HISTORY
     The em device driver first appeared in FreeBSD 4.4.  em was merged with the
     igb device driver and converted to the iflib framework in FreeBSD 12.0.

AUTHORS
     The em driver was originally  written  by	Intel  Corporation  <freebsd@in-
     tel.com>.	 It was merged with igb driver and converted to the iflib frame-
     work   by	  Matthew    Macy    <mmacy@mattmacy.io>    and    Sean    Bruno
     <sbruno@FreeBSD.org>.

FreeBSD 12.2			January 30, 2019			   EM(4)
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