.\"
.\" Copyright (c) 2007 The DragonFly Project.  All rights reserved.
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.\" modification, are permitted provided that the following conditions
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.\"    notice, this list of conditions and the following disclaimer.
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.\" $FreeBSD: releng/10.1/share/man/man4/et.4 228370 2011-12-09 19:17:51Z yongari $
.\"
.Dd December 9, 2011
.Dt ET 4
.Os
.Sh NAME
.Nm et
.Nd "Agere ET1310 10/100/Gigabit Ethernet driver"
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device miibus"
.Cd "device et"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
if_et_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver supports PCI Express Ethernet adapters based on the Agere ET1310 chip.
.\".Pp
.\"Support for Jumbo Frames is provided via the interface MTU setting.
.\"Selecting an MTU larger than 1500 bytes with the
.\".Xr ifconfig 8
.\"utility configures the adapter to receive and transmit Jumbo Frames.
.\"The maximum MTU setting for Jumbo Frames is 15572.
.\"This value coincides with the maximum Jumbo Frames size of 15594.
.Pp
The
.Nm
driver supports the following media types:
.Pp
.Bl -tag -width 10baseT/UTP -compact
.It autoselect
Enable autoselection of the media types and options.
The user can manually override
the autoselected mode by adding media options to the
.Pa /etc/rc.conf
file.
.Pp
.It 10baseT/UTP
Set 10Mbps operation.
The
.Ar mediaopt
option can also be used to select either
.Ar full-duplex
or
.Ar half-duplex
modes.
.Pp
.It 100baseTX
Set 100Mbps (Fast Ethernet) operation.
The
.Ar mediaopt
option can also be used to select either
.Ar full-duplex
or
.Ar half-duplex
modes.
.Pp
.It 1000baseT
Set 1000Mbps (Gigabit Ethernet) operation.
The
.Ar mediaopt
option can only be set to
.Ar full-duplex
mode.
.El
.Pp
The
.Nm
driver supports the following
.Ar media
options:
.Pp
.Bl -tag -width full-duplex -compact
.It full-duplex
Force full-duplex operation.
.Pp
.It half-duplex
Force half-duplex operation.
.El
.Pp
Note that the 1000baseT media type is only available
if it is supported by the adapter.
For more information on configuring this device, see
.Xr ifconfig 8 .
.Sh HARDWARE
The
.Nm
driver supports Agere ET1310 10/100/Gigabit
Ethernet adapters.
.Sh TUNABLES
.Bl -tag -width ".Va hw.et.rx_intr_npkts"
.It Va 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.
.It Va hw.et.rx_intr_delay
This value delays the generation of receive interrupts
in units of ~4 microseconds.
It is used together with
.Va hw.et.rx_intr_npkts
to achieve RX interrupt moderation.
The default value is 20.
.It Va 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.
.It Va hw.et.timer
This value controls how often a timer interrupt should be generated.
It is used together with
.Va hw.et.tx_intr_nsegs
to achieve TX interrupt moderation.
The default value is 1000000000 (nanoseconds).
.El
.Sh SEE ALSO
.Xr altq 4 ,
.Xr arp 4 ,
.Xr miibus 4 ,
.Xr netintro 4 ,
.Xr ng_ether 4 ,
.Xr vlan 4 ,
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
device driver first appeared in
.Dx 1.11 .
The first
.Fx
release to include it was
.Fx 8.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Sepherosa Ziehau Aq sepherosa@gmail.com
for
.Dx .
It was ported to
.Fx
by
.An Xin LI Aq delphij@FreeBSD.org .