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

# gem(4)

GEM 10/100/1Gb Ethernet device

## NAME

**gem** – GEM 10/100/1Gb Ethernet device

## SYNOPSIS

**gem\* at pci?** **gem\* at sbus?** **bmtphy\* at mii?** **brgphy\* at mii?** **eephy\* at mii?** **gentbi\* at mii?** **luphy\* at mii?** **lxtphy\* at mii?**

## DESCRIPTION

The **gem** driver provides support for various NICs based on the GEM Ethernet controller chips, including the following:

- Apple GMAC (10/100/1000baseT)

- Sun ERI (10/100baseT)

- Sun GEM (10/100/1000baseT)

- Sun GEM (1000baseSX)

It uses an external PHY or an external 10-bit interface.

The **gem** driver supports several media types, which are selected via the [ifconfig(8)](/ifconfig/8.md) command. The supported media types are:

- **media** autoselect

  Attempt to autoselect the media type (default)

- **media** 1000baseT **mediaopt** full-duplex

  Use 1000baseT on copper, full duplex

- **media** 1000baseT **mediaopt** half-duplex

  Use 1000baseT on copper, half duplex

- **media** 1000baseSX **mediaopt** full-duplex

  Use 1000baseSX on fiber, full duplex

- **media** 1000baseSX **mediaopt** half-duplex

  Use 1000baseSX on fiber, half duplex

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

  Use 100baseTX, full duplex

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

  Use 100baseTX, half duplex

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

  Use 10baseT, full duplex

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

  Use 10baseT, half duplex

## SEE ALSO

[arp(4)](/arp/4.md), [bmtphy(4)](/bmtphy/4.md), [brgphy(4)](/brgphy/4.md), [eephy(4)](/eephy/4.md), [gentbi(4)](/gentbi/4.md), [ifmedia(4)](/ifmedia/4.md), [inet(4)](/inet/4.md), [intro(4)](/intro/4.md), [luphy(4)](/luphy/4.md), [lxtphy(4)](/lxtphy/4.md), [netintro(4)](/netintro/4.md), [hostname.if(5)](/hostname.if/5.md), [ifconfig(8)](/ifconfig/8.md)

## HISTORY

OpenBSD support for **gem** first appeared in OpenBSD 3.0.