.\"	$OpenBSD: gem.4,v 1.4 2002/11/26 22:28:20 nate Exp $
.\"
.\" Copyright (c) 2001 Miodrag Vallat.
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.Dd October 5, 2001
.Dt GEM 4
.Os
.Sh NAME
.Nm gem
.Nd GEM gigabit ethernet interface
.Sh SYNOPSIS
.Cd "gem* at pci? dev ? function ?"
.Cd "bmtphy* at mii? phy ?"
.Cd "brgphy* at mii? phy ?"
.Cd "lxtphy* at mii? phy ?"
.\" .Cd "nsphy* at mii? phy ?"
.\" .Cd "qsphy* at mii? phy ?"
.Sh DESCRIPTION
The
.Nm
interface provides access to the 10Mb/s, 100Mb/s and 1Gb/s Ethernet networks.
The
.Nm
is found on the
.Tn Sun
GEM and ERI 10/100 boards, as well as the
.Tn Apple
internal GMAC ethernet.
.Pp
Each of the host's network addresses
is specified at boot time with an
.Dv SIOCSIFADDR
.Xr ioctl 2 .
The
.Nm
interface employs the address resolution protocol described in
.Xr arp 4
to dynamically map between Internet and Ethernet addresses on the local
network.
.Pp
When a
.Nm
interface is brought up, by default, it will attempt to auto-negotiate the
link speed and duplex.
The speeds are tried in descending order; first in full duplex mode, then
half duplex.
.Pp
The
.Nm
supports several media types, which are selected via the
.Xr ifconfig 8
command.
The supported media types are:
.Bl -tag -width "media autoselect" -offset indent
.It media autoselect
Attempt to autoselect the media type (default)
.\" Check and correct the gigabit modes. Are both copper and fiber supported?
.\" And in both duplex modes as well?
.It media 1000baseT  mediaopt full-duplex
Use 1000baseT on copper, full duplex
.It media 1000baseT Op mediaopt half-duplex
Use 1000baseT on copper, half duplex
.It media 1000baseSX  mediaopt full-duplex
Use 1000baseSX on fiber, full duplex
.It media 1000baseSX Op mediaopt half-duplex
Use 1000baseSX on fiber, half duplex
.It media 100baseTX  mediaopt full-duplex
Use 100baseTX, full duplex
.It media 100baseTX Op mediaopt half-duplex
Use 100baseTX, half duplex
.It media 10baseT mediaopt full-duplex
Use 10baseT, full duplex
.It media 10baseT Op mediaopt half-duplex
Use 10baseT, half duplex
.El
.Sh SEE ALSO
.Xr arp 4 ,
.Xr bmtphy 4 ,
.xr brgphy 4 ,
.Xr ifmedia 4 ,
.Xr inet 4 ,
.Xr intro 4 ,
.Xr lxtphy 4 ,
.Xr netintro 4 ,
.\" .Xr nsphy 4
.\" .Xr qsphy 4
.Xr hostname.if 5 ,
.Xr ifconfig 8
.Sh HISTORY
.Ox
support for the
.Nm
first appeared in
.Ox 3.0 .