---
name: "et"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/et/4"
---

# et(4)

Agere ET1310 10/100/Gigabit Ethernet driver

## NAME

**et** – Agere ET1310 10/100/Gigabit Ethernet driver

## SYNOPSIS

To compile this driver into the kernel, place the following lines in your kernel configuration file:

**device miibus** **device et**

Alternatively, to load the driver as a module at boot time, place the following line in [loader.conf(5)](/loader.conf/5.md):

```
if_et_load="YES"
```

## DESCRIPTION

The **et** driver supports PCI Express Ethernet adapters based on the Agere ET1310 chip.

The **et** driver supports the following media types:

- autoselect

  Enable autoselection of the media types and options. The user can manually override the autoselected mode by adding media options to the */etc/rc.conf* file.

- 10baseT/UTP

  Set 10Mbps operation. The *mediaopt* option can also be used to select either *full-duplex* or *half-duplex* modes.

- 100baseTX

  Set 100Mbps (Fast Ethernet) operation. The *mediaopt* option can also be used to select either *full-duplex* or *half-duplex* modes.

- 1000baseT

  Set 1000Mbps (Gigabit Ethernet) operation. The *mediaopt* option can only be set to *full-duplex* mode.

The **et** driver supports the following *media* options:

- full-duplex

  Force full-duplex operation.

- half-duplex

  Force half-duplex operation.

Note that the 1000baseT media type is only available if it is supported by the adapter. For more information on configuring this device, see [ifconfig(8)](/ifconfig/8.md).

## HARDWARE

The **et** driver supports Agere ET1310 10/100/Gigabit Ethernet adapters.

## TUNABLES

- *hw.et.rx\_intr\_npkts*

  This value controls how many packets should be received before a receive interrupt is generated. The default value is 32. It is recommended to set this value above 38 to prevent the host from being livelocked under a high degree of stress.

- *hw.et.rx\_intr\_delay*

  This value delays the generation of receive interrupts in units of ~4 microseconds. It is used together with *hw.et.rx\_intr\_npkts* to achieve RX interrupt moderation. The default value is 20.

- *hw.et.tx\_intr\_nsegs*

  This value controls how many segments (not packets) should be transmitted before a transmit interrupt is generated. The default value is 126. It is recommended to set this value below 280 to prevent the TX ring from underflowing.

- *hw.et.timer*

  This value controls how often a timer interrupt should be generated. It is used together with *hw.et.tx\_intr\_nsegs* to achieve TX interrupt moderation. The default value is 1000000000 (nanoseconds).

## SEE ALSO

[altq(4)](/altq/4.md), [arp(4)](/arp/4.md), [miibus(4)](/miibus/4.md), [netintro(4)](/netintro/4.md), [ng\_ether(4)](/ng_ether/4.md), [vlan(4)](/vlan/4.md), [ifconfig(8)](/ifconfig/8.md)

## HISTORY

The **et** device driver first appeared in DragonFly 1.11. The first FreeBSD release to include it was FreeBSD 8.0.

## AUTHORS

The **et** driver was written by Sepherosa Ziehau ⟨*sepherosa@gmail.com*⟩ for DragonFly. It was ported to FreeBSD by Xin LI ⟨*delphij@FreeBSD.org*⟩.