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EM(4) Device Drivers Manual EM(4)

emIntel PRO/1000 10/100/Gigabit Ethernet device

em* at pci?

The em driver provides support for PCI, PCI-X and PCI Express Gigabit Ethernet adapters based on the Intel 82540EM, 82540EP, 82541EI, 82541ER, 82541GI, 82541PI, 82542, 82543GC, 82544EI, 82544GC, 82545EM, 82545GM, 82546EB, 82546GB, 82547EI, 82547GI, 82562V, 82563EB, 82564EB, 82566DC, 82566DM, 82571EB, 82571GB, 82572EI, 82572GI, 82573E, 82573L, 82573V, 82574L, 82575EB, 82575GB, 82576EB, 82577LC, 82577LM, 82578DC, 82578DM, 82579LM, 82579V, 82580DB, 82580EB, 82583V, I210, I211, I217, I218, I350, I354 Ethernet controller chips and the embedded chips found on EP80579 platform, including the following:

The em driver supports IPv4 receive IP/TCP/UDP checksum offload and transmit TCP/UDP checksum offload on all but 82542-based adapters, VLAN tag insertion and stripping, and Jumbo frames on all but 82562V, 82566DC/82566DM and 82573E/82573L/82573V-based adapters. The 82562V Ethernet controller chip only supports 10/100 media types.

The em driver supports the following media types:

autoselect
Enables auto-negotiation for speed and duplex.
10baseT mediaopt full-duplex
Sets 10Mbps operation.
100baseTX mediaopt full-duplex
Sets 100Mbps operation.
1000baseLX
Sets 1000Mbps operation. Only full-duplex mode is supported at this speed.
1000baseSX
Sets 1000Mbps operation. Only full-duplex mode is supported at this speed.
1000baseT
Sets 1000Mbps operation. Only full-duplex mode is supported at this speed.

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

arp(4), gcu(4), ifmedia(4), intro(4), netintro(4), pci(4), hostname.if(5), ifconfig(8)

The em device driver first appeared in OpenBSD 3.2.

The em driver was written by Intel Corporation.

There are known performance issues with this driver when running UDP traffic with Jumbo frames.

There is a known compatibility issue where time to link is slow or link is not established between 82541/82547 controllers and some switches. Known switches include:

February 22, 2014 OpenBSD-5.6