EM(4)                  FreeBSD 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
     identification LEDs of the adapters supported by the em driver can be
     controlled via the led(4) API for localization purposes.  For further
     hardware information, 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.
     Selecting an MTU larger than 1500 bytes with the ifconfig(8) utility
     configures 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.
             Default 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 descriptors, while others can have up to 4096.

     hw.em.txd
             Number of transmit 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 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@intel.com>.  It was merged with igb driver and converted to the
     iflib framework by Matthew Macy <mmacy@mattmacy.io> and Sean Bruno
     <sbruno@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6        January 30, 2019        FreeBSD 13.1-RELEASE-p6