.\"
.\" Copyright 2021 Intel Corp
.\" Copyright 2021 Rubicon Communications, LLC (Netgate)
.\" SPDX-License-Identifier: BSD-3-Clause
.\"
.Dd August 30, 2026
.Dt IGC 4
.Os
.Sh NAME
.Nm igc
.Nd Intel Ethernet Controller I225 2.5GbE 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 iflib"
.Cd "device igc"
.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_igc_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides support for any PCI Express adapter or LOM (LAN
On Motherboard) based on the Intel I225 Multi Gigabit Controller.
The driver supports Transmit/Receive checksum offload, Jumbo Frames,
MSI/MSI-X, TSO, and RSS.
.Pp
On systems that expose PCI power-management wake, the driver supports the
.Cm wol_magic ,
.Cm wol_ucast ,
and
.Cm wol_mcast
capabilities shown by
.Xr ifconfig 8 .
Magic-packet wake is enabled by default and any advertised wake mode can be
enabled or disabled with
.Xr ifconfig 8 .
Waking the system from an ACPI sleep state also requires enabling the
corresponding device wake source when it is exposed, for example:
.Bd -literal -offset indent
sysctl dev.igc.0.wake=1
.Ed
The interface wake capabilities select the controller packet filters; they do
not enable the ACPI wake source.
.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 size for Jumbo Frames is 9216 bytes.
.Pp
This driver version supports VLAN hardware insertion / extraction,
VLAN checksum offload, and VLAN hardware filtering.
For information on enabling VLANs, see
.Xr ifconfig 8 .
.Pp
The identification LED of an adapter supported by the
.Nm
driver can be controlled via the
.Xr led 4
interface at
.Pa /dev/led/igc* .
The
.Nm
driver supports the following media types:
.Bl -tag -width ".Cm 10baseT/UTP"
.It Cm autoselect
Enables auto-negotiation for speed and duplex.
.It Cm 10baseT/UTP
Sets 10Mbps operation.
Use the
.Cm mediaopt
option to select
.Cm half-duplex
mode.
.It Cm 100baseTX
Sets 100Mbps operation.
Use the
.Cm mediaopt
option to select
.Cm half-duplex
mode.
.It Cm 1000baseT
Sets 1000Mbps operation.
Only
.Cm full-duplex
mode is supported at this speed.
.It Cm 2500baseT
Sets 2500Mbps operation.
Only
.Cm full-duplex
mode is supported at this speed.
.El
.Sh HARDWARE
The
.Nm
driver supports the following 2.5Gb Ethernet controllers:
.Pp
.Bl -bullet -compact
.It
I220-V
.It
I221-V
.It
I225-LM
.It
I225-LMvP(2)
.It
I225-V
.It
I225-IT, I225-IT(2)
.It
I225-K, I225-K(2)
.It
I226-LM
.It
I226-LMvP
.It
I226-V
.It
I226-IT
.It
I226-K
.El
.Sh LOADER TUNABLES
Tunables can be set at the
.Xr loader 8
prompt before booting the kernel or stored in
.Xr loader.conf 5 .
.Bl -tag -width indent
.It Va hw.igc.igc_disable_crc_stripping
Disable or enable hardware stripping of CRC field.
This is mostly useful on BMC/IPMI shared interfaces where stripping the
CRC causes remote access over IPMI to fail.
Default 0 (enabled).
.It Va hw.igc.sbp
Show bad packets when in promiscuous mode.
Default is false.
.It Va hw.igc.eee_setting
Disable or enable Energy Efficient Ethernet.
Default 1 (disabled).
.It Va hw.igc.max_interrupt_rate
Maximum device interrupts per second.
The default is 8000.
This is the rate used when adaptive interrupt moderation is disabled, and
the fallback when it has no usable measurement.
.It Va hw.igc.enable_aim
Adaptive interrupt moderation.
The interrupt rate is derived from the average size of the packets seen
since the previous interrupt, so that bulk traffic is coalesced while small
packet traffic keeps its latency.
A value of 0 disables it and pins the rate to
.Va hw.igc.max_interrupt_rate ,
1 selects the normal range, and 2 selects the low-latency range.
The default value is 1.
Setting 2 raises the interrupt rate substantially on small packet workloads
and is rarely a win; prefer the default unless latency has been measured to
matter more than the additional interrupt load.
.El
.Sh DIAGNOSTICS
.Bl -diag
.It "igc%d: Hardware Initialization Failed"
A fatal initialization error has occurred.
.It "igc%d: Unable to allocate bus resource: memory"
A fatal initialization error has occurred.
.It "igc%d: Invalid MAC address"
The MAC address programmed into the EEPROM is either empty or a multicast or
broadcast address.
.El
.Sh SEE ALSO
.Xr altq 4 ,
.Xr arp 4 ,
.Xr iflib 4 ,
.Xr led 4 ,
.Xr netintro 4 ,
.Xr ng_ether 4 ,
.Xr vlan 4 ,
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 13.1 .
.Sh AUTHORS
.An -nosplit
The
.Nm
was originally written by
.An Intel Corporation
and converted to the
.Xr iflib 4
framework by
.An Netgate .