.. SPDX-License-Identifier: GPL-2.0+

==========================================================
Linux Base Driver for Intel(R) Ethernet Network Connection
==========================================================

Intel Gigabit Linux driver.
Copyright(c) 1999-2018 Intel Corporation.

Contents
========

- Identifying Your Adapter
- Command Line Parameters
- Additional Configurations
- Support


Identifying Your Adapter
========================
For information on how to identify your adapter, and for the latest Intel
network drivers, refer to the Intel Support website:
https://www.intel.com/support


Command Line Parameters
========================
If the driver is built as a module, the following optional parameters are used
by entering them on the command line with the modprobe command using this
syntax::

    modprobe igb [<option>=<VAL1>,<VAL2>,...]

There needs to be a <VAL#> for each network port in the system supported by
this driver. The values will be applied to each instance, in function order.
For example::

    modprobe igb max_vfs=2,4

In this case, there are two network ports supported by igb in the system.

NOTE: A descriptor describes a data buffer and attributes related to the data
buffer. This information is accessed by the hardware.

max_vfs
-------
:Valid Range: 0-7

This parameter adds support for SR-IOV. It causes the driver to spawn up to
max_vfs worth of virtual functions.  If the value is greater than 0 it will
also force the VMDq parameter to be 1 or more.

The parameters for the driver are referenced by position. Thus, if you have a
dual port adapter, or more than one adapter in your system, and want N virtual
functions per port, you must specify a number for each port with each parameter
separated by a comma. For example::

    modprobe igb max_vfs=4

This will spawn 4 VFs on the first port.

::

    modprobe igb max_vfs=2,4

This will spawn 2 VFs on the first port and 4 VFs on the second port.

NOTE: Caution must be used in loading the driver with these parameters.
Depending on your system configuration, number of slots, etc., it is impossible
to predict in all cases where the positions would be on the command line.

NOTE: Neither the device nor the driver control how VFs are mapped into config
space. Bus layout will vary by operating system. On operating systems that
support it, you can check sysfs to find the mapping.

NOTE: When either SR-IOV mode or VMDq mode is enabled, hardware VLAN filtering
and VLAN tag stripping/insertion will remain enabled. Please remove the old
VLAN filter before the new VLAN filter is added. For example::

    ip link set eth0 vf 0 vlan 100	// set vlan 100 for VF 0
    ip link set eth0 vf 0 vlan 0	// Delete vlan 100
    ip link set eth0 vf 0 vlan 200	// set a new vlan 200 for VF 0

Debug
-----
:Valid Range: 0-16 (0=none,...,16=all)
:Default Value: 0

This parameter adjusts the level debug messages displayed in the system logs.


Additional Features and Configurations
======================================

Jumbo Frames
------------
Jumbo Frames support is enabled by changing the Maximum Transmission Unit (MTU)
to a value larger than the default value of 1500.

Use the ifconfig command to increase the MTU size. For example, enter the
following where <x> is the interface number::

    ifconfig eth<x> mtu 9000 up

Alternatively, you can use the ip command as follows::

    ip link set mtu 9000 dev eth<x>
    ip link set up dev eth<x>

This setting is not saved across reboots. The setting change can be made
permanent by adding 'MTU=9000' to the file:

- For RHEL: /etc/sysconfig/network-scripts/ifcfg-eth<x>
- For SLES: /etc/sysconfig/network/<config_file>

NOTE: The maximum MTU setting for Jumbo Frames is 9216. This value coincides
with the maximum Jumbo Frames size of 9234 bytes.

NOTE: Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
poor performance or loss of link.


ethtool
-------
The driver utilizes the ethtool interface for driver configuration and
diagnostics, as well as displaying statistical information. The latest ethtool
version is required for this functionality. Download it at:

https://www.kernel.org/pub/software/network/ethtool/


Enabling Wake on LAN (WoL)
--------------------------
WoL is configured through the ethtool utility.

WoL will be enabled on the system during the next shut down or reboot. For
this driver version, in order to enable WoL, the igb driver must be loaded
prior to shutting down or suspending the system.

NOTE: Wake on LAN is only supported on port A of multi-port devices.  Also
Wake On LAN is not supported for the following device:
- Intel(R) Gigabit VT Quad Port Server Adapter


Multiqueue
----------
In this mode, a separate MSI-X vector is allocated for each queue and one for
"other" interrupts such as link status change and errors. All interrupts are
throttled via interrupt moderation. Interrupt moderation must be used to avoid
interrupt storms while the driver is processing one interrupt. The moderation
value should be at least as large as the expected time for the driver to
process an interrupt. Multiqueue is off by default.

REQUIREMENTS: MSI-X support is required for Multiqueue. If MSI-X is not found,
the system will fallback to MSI or to Legacy interrupts. This driver supports
receive multiqueue on all kernels that support MSI-X.

NOTE: On some kernels a reboot is required to switch between single queue mode
and multiqueue mode or vice-versa.


MAC and VLAN anti-spoofing feature
----------------------------------
When a malicious driver attempts to send a spoofed packet, it is dropped by the
hardware and not transmitted.

An interrupt is sent to the PF driver notifying it of the spoof attempt. When a
spoofed packet is detected, the PF driver will send the following message to
the system log (displayed by the "dmesg" command):
Spoof event(s) detected on VF(n), where n = the VF that attempted to do the
spoofing


Setting MAC Address, VLAN and Rate Limit Using IProute2 Tool
------------------------------------------------------------
You can set a MAC address of a Virtual Function (VF), a default VLAN and the
rate limit using the IProute2 tool. Download the latest version of the
IProute2 tool from Sourceforge if your version does not have all the features
you require.

Credit Based Shaper (Qav Mode)
------------------------------
When enabling the CBS qdisc in the hardware offload mode, traffic shaping using
the CBS (described in the IEEE 802.1Q-2018 Section 8.6.8.2 and discussed in the
Annex L) algorithm will run in the i210 controller, so it's more accurate and
uses less CPU.

When using offloaded CBS, and the traffic rate obeys the configured rate
(doesn't go above it), CBS should have little to no effect in the latency.

The offloaded version of the algorithm has some limits, caused by how the idle
slope is expressed in the adapter's registers. It can only represent idle slopes
in 16.38431 kbps units, which means that if a idle slope of 2576kbps is
requested, the controller will be configured to use a idle slope of ~2589 kbps,
because the driver rounds the value up. For more details, see the comments on
:c:func:`igb_config_tx_modes()`.

NOTE: This feature is exclusive to i210 models.


Support
=======
For general information, go to the Intel support website at:
https://www.intel.com/support/

If an issue is identified with the released source code on a supported kernel
with a supported adapter, email the specific information related to the issue
to intel-wired-lan@lists.osuosl.org.
