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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 and 82573 Ethernet controller
     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.  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 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 and 82573 controller chips:

     ·   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 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.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
             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.

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〉.

SEE ALSO

     altq(4), arp(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).