---
name: "ef"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["linux", "openbsd"]
url: "https://new.carta.tech/ef"
---

# ef(4)

3Com Fast EtherLink ISA (3c515) 10/100 Ethernet device

## NAME

**ef** – 3Com Fast EtherLink ISA (3c515) 10/100 Ethernet device

## SYNOPSIS

**ef\* at isapnp?** **nsphy\* at mii?**

## DESCRIPTION

The **ef** device driver supports the 3Com Fast EtherLink ISA family of Ethernet cards, and embedded controllers based on the 3Com “corkscrew” EtherLink chips.

The following media types and options (as given to [ifconfig(8)](/ifconfig/8.md)) are supported:

- **media** autoselect

  Enable autoselection of the media type and options (default).

- **media** 100baseTX **mediaopt** full-duplex

  Set 100Mbps (Fast Ethernet) operation and force full-duplex mode.

- **media** 100baseTX **mediaopt** half-duplex

  Set 100Mbps (Fast Ethernet) operation and force half-duplex mode.

- **media** 10baseT **mediaopt** full-duplex

  Set 10Mbps operation and force full-duplex.

- **media** 10baseT **mediaopt** half-duplex

  Set 10Mbps operation and force half-duplex.

If no media options are present, the **ef** driver places the card into autoselect mode.

For more information on configuring this device, see [ifconfig(8)](/ifconfig/8.md).

## DIAGNOSTICS

- ef0: adapter failure (XXXX)

  A fatal error during receive or transmit has occurred.

- ef0: eeprom failed to come ready

  When reading/writing the EEPROM, the busy bit failed to clear. This may indicate a hardware problem.

- ef0: device timeout

  The device has stopped responding to the network, or there is a problem with the network connection (cable).

## SEE ALSO

[ifmedia(4)](/ifmedia/4.md), [intro(4)](/intro/4.md), [isapnp(4)](/isapnp/4.md), [nsphy(4)](/nsphy/4.md), [hostname.if(5)](/hostname.if/5.md), [ifconfig(8)](/ifconfig/8.md)

## HISTORY

The **ef** device driver first appeared in OpenBSD 2.6.

## AUTHORS

The **ef** driver was written by Jason L. Wright ⟨*jason@thought.net*⟩.