em(4)

EM(4)

NAME
em - Intel(R) Ethernet Driver for the FreeBSD* operating system

SYNOPSIS
device em

DESCRIPTION
The em driver provides support for Intel(R) Ethernet devices based on the Intel 82540, 82541, 82542, 82543, 82544, 82545, 82546, 82547, and 82575 Ethernet controller chips. The driver does not support Transmit/Receive checksum offload and Jumbo Frames on adapters based on the Intel 82542 and 82573 LAN controllers.

For questions related to hardware requirements, refer to the documentation supplied with your adapter.

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 setting for Jumbo Frames is 16110. This value coincides with the maximum Jumbo Frames size of 16132. Some Intel gigabit adapters that support Jumbo Frames have a frame size limit of 9238 bytes, with a corresponding MTU size limit of 9216 bytes. The adapters with this limitation are based on the Intel(R) 82571EB, 82572EI, 82573L, 82563EB and 82564EI LAN controllers.

The following Intel gigabit LAN devices do not support Jumbo Frames:

Intel(R) PRO/1000 PM Network Connection

Adapters based on the Intel(R) 82542 and 82573 LAN controllers.

This driver version supports VLANs. For information on enabling VLANs, see the README. 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 both full-duplex and half-duplex. Use mediaopt to force the driver to either of these settings. Note that the only valid parameter for mediaopt is full-duplex; to force the driver to half-duplex when running at less than gibabit speed, leave mediaopt unspecified.

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

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 additional information regarding building and installation, see the README included with the driver. For general information, go to the Intel support website at: http://www.intel.com/support/

If an issue is identified with the released source code on a supported kernel with a supported adapter, email the specific information related to the issue to freebsd@intel.com

SEE ALSO
arp(4), netintro(4), ng_ether(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 <freebsd@intel.com>