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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 line in your
     kernel configuration file:

	   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 con-
     troller chips.  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 documenta-
     tion supplied with	your Intel PRO/1000 adapter.  All hardware require-
     ments 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 con-
     figures the adapter to receive and	transmit Jumbo Frames.	The maximum
     MTU size for Jumbo	Frames is 16114.

     This driver version supports 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, and 82574 controller chips:

     +o	 Intel PRO/1000	CT Network Connection (82547)
     +o	 Intel PRO/1000	F Server Adapter (82543)
     +o	 Intel PRO/1000	Gigabit	Server Adapter (82542)
     +o	 Intel PRO/1000	GT Desktop Adapter (82541PI)
     +o	 Intel PRO/1000	MF Dual	Port Server Adapter (82546)
     +o	 Intel PRO/1000	MF Server Adapter (82545)
     +o	 Intel PRO/1000	MF Server Adapter (LX) (82545)
     +o	 Intel PRO/1000	MT Desktop Adapter (82540)
     +o	 Intel PRO/1000	MT Desktop Adapter (82541)
     +o	 Intel PRO/1000	MT Dual	Port Server Adapter (82546)
     +o	 Intel PRO/1000	MT Quad	Port Server Adapter (82546EB)
     +o	 Intel PRO/1000	MT Server Adapter (82545)
     +o	 Intel PRO/1000	PF Dual	Port Server Adapter (82571)
     +o	 Intel PRO/1000	PF Quad	Port Server Adapter (82571)
     +o	 Intel PRO/1000	PF Server Adapter (82572)
     +o	 Intel PRO/1000	PT Desktop Adapter (82572)
     +o	 Intel PRO/1000	PT Dual	Port Server Adapter (82571)
     +o	 Intel PRO/1000	PT Quad	Port Server Adapter (82571)
     +o	 Intel PRO/1000	PT Server Adapter (82572)
     +o	 Intel PRO/1000	T Desktop Adapter (82544)
     +o	 Intel PRO/1000	T Server Adapter (82543)
     +o	 Intel PRO/1000	XF Server Adapter (82544)
     +o	 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.rxd
	     Number of receive descriptors allocated by	the driver.  The
	     default value is 256.  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 256.  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	maxi-
	     mum 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	maxi-
	     mum delay in which	a transmit interrupt is	generated.

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 <freebsdnic@mailbox.intel.com>.

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

SEE ALSO
     altq(4), arp(4), igb(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.

AUTHORS
     The em driver was written by Intel	Corporation
     <freebsdnic@mailbox.intel.com>.

BUGS
     Hardware-assisted VLAN processing is disabled by default.	You can	enable
     it	on an em interface using ifconfig(8).

FreeBSD	9.2			 May 14, 2010			   FreeBSD 9.2

NAME | SYNOPSIS | DESCRIPTION | HARDWARE | LOADER TUNABLES | DIAGNOSTICS | SUPPORT | FILES | EXAMPLES | SEE ALSO | HISTORY | AUTHORS | BUGS

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