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

April 22, 2013

Contents
========

- In This Release
- Identifying Your Adapter
- Building and Installation
- Command Line Parameters
- Additional Configurations
- Known Issues/Troubleshooting
- Support

In This Release
================

This file describes the igb Linux* Base Driver for Intel Ethernet Network 
Connection.  This driver supports the 2.4.x, 2.6.x, and 3.x kernels.

This driver is only supported as a loadable module at this time.  Intel is
not supplying patches against the kernel source to allow for static linking
of the driver.  For questions related to hardware requirements, refer to the
documentation supplied with your Intel Gigabit adapter.  All hardware
requirements listed apply to use with Linux.

The following features are now available in supported kernels:
 - Native VLANs
 - Channel Bonding (teaming)
 - SNMP

Channel Bonding documentation can be found in the Linux kernel source:
/Documentation/networking/bonding.txt

The igb driver supports IEEE 1588 time stamping for kernels 2.6.30 and above.  

The driver information previously displayed in the /proc filesystem is not
supported in this release.  Alternatively, you can use ethtool (version 1.6
or later), lspci, and ifconfig to obtain the same information.

Instructions on updating ethtool can be found in the section "Additional
Configurations" later in this document.

Identifying Your Adapter
========================

For more information on how to identify your adapter, go to the Adapter &
Driver ID Guide at:

    http://support.intel.com/support/go/network/adapter/idguide.htm

For the latest Intel network drivers for Linux, refer to the following
website.  Select the link for your adapter.

    http://support.intel.com/support/go/network/adapter/home.htm

Building and Installation
=========================

To build a binary RPM* package of this driver, run 'rpmbuild -tb
<filename.tar.gz>'.  Replace <filename.tar.gz> with the specific filename
of the driver.

NOTE: For the build to work properly, the currently running kernel MUST
      match the version and configuration of the installed kernel sources.
      If you have just recompiled the kernel reboot the system now.

      RPM functionality has only been tested in Red Hat distributions.

1. Move the base driver tar file to the directory of your choice.  For
   example, use /home/username/igb or /usr/local/src/igb.

2. Untar/unzip archive:

     tar zxf igb-x.x.x.tar.gz

3. Change to the driver src directory:

     cd igb-x.x.x/src/

4. Compile the driver module:

     make install

   The binary will be installed as:

     /lib/modules/<KERNEL VERSION>/kernel/drivers/net/igb/igb.[k]o

   The install locations listed above are the default locations.  They
   might not be correct for certain Linux distributions.  

5. Load the module using the modprobe command:

     modprobe igb

   With 2.6 based kernels also make sure that older igb drivers are
   removed from the kernel, before loading the new module:

     rmmod igb; modprobe igb

6. Assign an IP address to the interface by entering the following, where
   x is the interface number:

     ifconfig ethx <IP_address>

7. Verify that the interface works.  Enter the following, where <IP_address>
   is the IP address for another machine on the same subnet as the
   interface that is being tested:

     ping  <IP_address>

TROUBLESHOOTING: Some systems have trouble supporting MSI and/or MSI-X 
interrupts. If you believe your system needs to disable this style of 
interrupt, the driver can be built and installed with the command:

     make CFLAGS_EXTRA=-DDISABLE_PCI_MSI install

Normally the driver will generate an interrupt every two seconds, so if 
you can see that you're no longer getting interrupts in cat /proc/interrupts
for the ethX igb device, then this workaround may be necessary.

To build igb driver with DCA:
------------------------------
 
If your kernel supports DCA, the driver will build by default with DCA enabled.

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 InterruptThrottleRate=16000,16000

In this case, there are two network ports supported by igb in the system. The default value for each parameter is generally the recommended setting, unless otherwise noted.


NOTES:  For more information about the AutoNeg, Duplex, and Speed parameters, 
        see the Speed and Duplex Configuration section in this document.
        
        For more information about the InterruptThrottleRate,
        parameter, see the application note at:
        http://www.intel.com/design/network/applnots/ap450.htm

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

InterruptThrottleRate
---------------------
Valid Range:   0,1,3,100-100000 (0=off, 1=dynamic, 3=dynamic conservative)
Default Value: 3

The driver can limit the amount of interrupts per second that the adapter
will generate for incoming packets. It does this by writing a value to the 
adapter that is based on the maximum amount of interrupts that the adapter 
will generate per second.

Setting InterruptThrottleRate to a value greater or equal to 100
will program the adapter to send out a maximum of that many interrupts
per second, even if more packets have come in. This reduces interrupt
load on the system and can lower CPU utilization under heavy load,
but will increase latency as packets are not processed as quickly.

The default behaviour of the driver previously assumed a static 
InterruptThrottleRate value of 8000, providing a good fallback value for 
all traffic types,but lacking in small packet performance and latency. 
The hardware can handle many more small packets per second however, and 
for this reason an adaptive interrupt moderation algorithm was implemented.

The driver has two adaptive modes (setting 1 or 3) in which it dynamically
adjusts the InterruptThrottleRate value based on the traffic that it receives.
After determining the type of incoming traffic in the last timeframe, it will
adjust the InterruptThrottleRate to an appropriate value for that traffic.

The algorithm classifies the incoming traffic every interval into
classes.  Once the class is determined, the InterruptThrottleRate value is 
adjusted to suit that traffic type the best. There are three classes defined: 
"Bulk traffic", for large amounts of packets of normal size; "Low latency",
for small amounts of traffic and/or a significant percentage of small
packets; and "Lowest latency", for almost completely small packets or 
minimal traffic.

In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 
for traffic that falls in class "Bulk traffic". If traffic falls in the "Low 
latency" or "Lowest latency" class, the InterruptThrottleRate is increased 
stepwise to 20000. This default mode is suitable for most applications.

For situations where low latency is vital such as cluster or
grid computing, the algorithm can reduce latency even more when
InterruptThrottleRate is set to mode 1. In this mode, which operates
the same as mode 3, the InterruptThrottleRate will be increased stepwise to 
70000 for traffic in class "Lowest latency".

Setting InterruptThrottleRate to 0 turns off any interrupt moderation
and may improve small packet latency, but is generally not suitable
for bulk throughput traffic.

NOTE:  Dynamic interrupt throttling is only applicable to adapters
       operating in MSI or Legacy interrupt mode, using a single
       receive queue.

NOTE:  When igb is loaded with default settings and multiple adapters
       are in use simultaneously, the CPU utilization may increase non-
       linearly.  In order to limit the CPU utilization without impacting
       the overall throughput, we recommend that you load the driver as
       follows:

           modprobe igb InterruptThrottleRate=3000,3000,3000

       This sets the InterruptThrottleRate to 3000 interrupts/sec for
       the first, second, and third instances of the driver.  The range
       of 2000 to 3000 interrupts per second works on a majority of
       systems and is a good starting point, but the optimal value will
       be platform-specific.  If CPU utilization is not a concern, use
       default driver settings.

LLI (Low Latency Interrupts)
---------------------------- 
LLI allows for immediate generation of an interrupt upon processing receive 
packets that match certain criteria as set by the parameters described below. 
LLI parameters are not enabled when Legacy interrupts are used. You must be 
using MSI or MSI-X (see cat /proc/interrupts) to successfully use LLI.

LLIPort
-------
Valid Range:   0-65535
Default Value: 0 (disabled)

LLI is configured with the LLIPort command-line parameter, which specifies 
which TCP port should generate Low Latency Interrupts.

For example, using LLIPort=80 would cause the board to generate an 
immediate interrupt upon receipt of any packet sent to TCP port 80 on the 
local machine.

WARNING: Enabling LLI can result in an excessive number of interrupts/second 
that may cause problems with the system and in some cases may cause a kernel 
panic. 

LLIPush
-------
Valid Range:   0-1
Default Value: 0 (disabled)

Can be set to be enabled or disabled (default). It is most 
effective in an environment with many small transactions.
NOTE: Enabling LLIPush may allow a denial of service attack.

LLISize
-------
Valid Range:   0-1500
Default Value: 0 (disabled)

Causes an immediate interrupt if the board receives a packet smaller 
than the specified size.

IntMode
-------
Valid Range: 0 - 2 (0 = Legacy Int, 1 = MSI and 2 = MSI-X)
Default Value: 2

IntMode controls allow load time control over the type of interrupt
registered for by the driver.  MSI-X is required for multiple queue
support, and some kernels and combinations of kernel .config options will
force a lower level of interrupt support.  'cat /proc/interrupts' will show
different values for each type of interrupt.

RSS
---
Valid Range:   0-8
Default Value: 1

0 - Assign up to whichever is less, number of CPUS or number of queues
X - Assign X queues where X is less than or equal to maximum number of queues.
    The driver allows maximum supported queue value. For example, I350-based 
    adapters allow RSS=8 (where 8-queues is the maximum allowable queues).

Note: for 82575-based adapters the maximum number of queues is 4; for 
82576-based and newer adapters it is 8; for I210-based adapters it is 4 queues;
and for I211-based adapters it is 2 queues.

This parameter is also affected by the VMDq parameter in that it will limit the
queues more.

      VMDQ
Model 0  1  2  3+
82575 4  4  3  1
82576 8  2  2  2
82580 8  1  1  1

VMDQ
----
Valid Range:  0 - 4 on 82575-based adapters; and 0 - 8 for 82576/82580-based 
adapters.
Default Value: 0

Supports enabling VMDq pools as this is needed to support SR-IOV.

0 - disabled
1 - sets the netdev as pool 0
2+ - add additional queues but they currently are not used.

This parameter is forced to 1 or more if the max_vfs module parameter is used. 
In addition the number of queues available for RSS is limited if this is set to
1 or greater.

NOTE: When either SR-IOV mode or VMDq mode is enabled, hardware VLAN filtering 
and VLAN tag stripping/insertion will remain enabled.
 
max_vfs
-------
Valid Range:   0-7
Default Value: 0

If the value is greater than 0 it will also force the VMDq parameter to be 1 
or more.

This parameter adds support for SR-IOV.  It causes the driver to spawn up to 
max_vfs worth of virtual function.  

  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
  
QueuePairs
----------
Valid Range:  0-1
Default Value:  1 (TX and RX will be paired onto one interrupt vector)

If set to 0, when MSI-X is enabled, the TX and RX will attempt to occupy
separate vectors.    

This option can be overridden to 1 if there are not sufficient interrupts
available.  This can occur if any combination of RSS, VMDQ, and max_vfs 
results in more than 4 queues being used.

Node
----
Valid Range:   0-n
Default Value: -1 (off)

  0 - n: where n is the number of the NUMA node that should be used to 
         allocate memory for this adapter port. 
  -1: uses the driver default of allocating memory on whichever processor is
      running modprobe. 

The Node parameter will allow you to pick which NUMA node you want to have the
adapter allocate memory from.  All driver structures, in-memory queues, and 
receive buffers will be allocated on the node specified.  This parameter is
only useful when interrupt affinity is specified, otherwise some portion of the
time the interrupt could run on a different core than the memory is allocated 
on, causing slower memory access and impacting throughput, CPU, or both.

EEE
---
Valid Range:  0-1
Default Value: 1 (enabled)

A link between two EEE-compliant devices will result in periodic bursts of 
data followed by periods where the link is in an idle state. This Low
Power Idle (LPI) state is supported in both 1Gbps and 100Mbps link speeds. 
NOTE: EEE support requires autonegotiation.

DMAC
----
Valid Range: 0, 250, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 
9000, 10000.
Default Value: 0 (disabled)
  
Enables or disables DMA Coalescing feature. Values are in usec’s and increase
the internal DMA Coalescing feature’s internal timer.  DMA (Direct Memory 
Access) allows the network device to move packet data directly to the 
system's memory, reducing CPU utilization. However, the frequency and random
intervals at which packets arrive do not allow the system to enter a lower 
power state. DMA Coalescing allows the adapter to collect packets before it 
initiates a DMA event. This may increase network latency but also increases
the chances that the system will enter a lower power state. 

Turning on DMA Coalescing may save energy with kernel 2.6.32 and later. This
will impart the greatest chance for your system to consume less power. DMA 
Coalescing is effective in helping potentially saving the platform power only
when it is enabled across all active ports.

InterruptThrottleRate (ITR) should be set to dynamic. When ITR=0, DMA 
Coalescing is automatically disabled. 
 
A whitepaper containing information on how to best configure your platform 
is available on the Intel website.

MDD (Malicious Driver Detection)
--------------------------------
Valid Range: 0, 1; 0 = Disable, 1 = Enable
Default Value: 1

This parameter is only relevant for I350 devices operating in SR-IOV mode. When
this parameter is set, the driver detects malicious VF driver and disables its
TX/RX queues until a VF driver reset occurs.
 

Additional Configurations
=========================

  Configuring the Driver on Different Distributions
  -------------------------------------------------
  Configuring a network driver to load properly when the system is started
  is distribution dependent.  Typically, the configuration process involves
  adding an alias line to /etc/modules.conf or /etc/modprobe.conf as well
  as editing other system startup scripts and/or configuration files.  Many
  popular Linux distributions ship with tools to make these changes for you.
  To learn the proper way to configure a network device for your system,
  refer to your distribution documentation.  If during this process you are
  asked for the driver or module name, the name for the Linux Base Driver
  for the Gigabit Family of Adapters is igb.

  As an example, if you install the igb driver for two Gigabit adapters 
  (eth0 and eth1) and want to set the interrupt mode to MSI-X and MSI 
  respectively, add the following to modules.conf or /etc/modprobe.conf:

       alias eth0 igb
       alias eth1 igb
       options igb IntMode=2,1

  Viewing Link Messages
  ---------------------
  Link messages will not be displayed to the console if the distribution is
  restricting system messages.  In order to see network driver link messages
  on your console, set dmesg to eight by entering the following:

       dmesg -n 8

  NOTE: This setting is not saved across reboots.

  Jumbo Frames
  ------------
  Jumbo Frames support is enabled by changing the MTU to a value larger than
  the default of 1500.  Use the ifconfig command to increase the MTU size.
  For example:

       ifconfig eth<x> mtu 9000 up

  This setting is not saved across reboots.  It can be made permanent if
  you add:

       MTU=9000

   to the file /etc/sysconfig/network-scripts/ifcfg-eth<x>.  This example
   applies to the Red Hat distributions; other distributions may store this
   setting in a different location.

  Notes:

  - To enable Jumbo Frames, increase the MTU size on the interface beyond
    1500.

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

  - 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.  ethtool
  version 3.0 or later is required for this functionality, although we 
  strongly recommend downloading the latest version at:

  http://ftp.kernel.org/pub/software/network/ethtool/.

  Speed and Duplex Configuration
  ------------------------------
  In addressing speed and duplex configuration issues, you need to 
  distinguish between copper-based adapters and fiber-based adapters. 

  In the default mode, an Intel(R) Network Adapter using copper connections 
  will attempt to auto-negotiate with its link partner to
  determine the best setting. If the adapter cannot establish link with the 
  link partner using auto-negotiation, you may need to manually configure the 
  adapter and link partner to identical settings to establish link and pass
  packets. This should only be needed when attempting to link with an older 
  switch that does not support auto-negotiation or one that has been forced 
  to a specific speed or duplex mode. Your link partner must match the 
  setting you choose. 
  
  Speed and Duplex are configured through the ethtool* utility. ethtool is 
  included with all versions of Red Hat after Red Hat 7.2. For other Linux
  distributions, download and install ethtool from the following website: 
  <a href="http://ftp.kernel.org/pub/software/network/ethtool/.

  Caution: Only experienced network administrators should force speed and 
  duplex manually. The settings at the switch must always match the adapter 
  settings. Adapter performance may suffer or your adapter may not 
  operate if you configure the adapter differently from your switch.

  An Intel® Network Adapter using fiber-based connections, however, will not 
  attempt auto-negotiate with its link partner since those adapters operate 
  only in full duplex, and only at their native speed. 

  
  Enabling Wake on LAN* (WoL)
  ---------------------------
  WoL is configured through the ethtool* utility.  ethtool is included with
  all versions of Red Hat after Red Hat 7.2.  For other Linux distributions,
  download and install ethtool from the following website:
  http://sourceforge.net/projects/gkernel.

  For instructions on enabling WoL with ethtool, refer to the website listed
  above.

  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 when shutting down or rebooting the system.

  Wake On LAN is only supported on port A of multi-port adapters.

  Wake On LAN is not supported for the 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 multiqueue in kernel versions 2.6.24 and greater. This driver 
  supports receive multiqueue on all kernels that support MSI-X. 
  NOTES: Do not use MSI-X with the 2.6.19 or 2.6.20 kernels.
  On some kernels a reboot is required to switch between a single queue mode
  and multiqueue modes, or vice-versa.

  LRO
  ---
  Large Receive Offload (LRO) is a technique for increasing inbound throughput
  of high-bandwidth network connections by reducing CPU overhead. It works by
  aggregating multiple incoming packets from a single stream into a larger 
  buffer before they are passed higher up the networking stack, thus reducing
  the number of packets that have to be processed. LRO combines multiple 
  Ethernet frames into a single receive in the stack, thereby potentially 
  decreasing CPU utilization for receives.

  NOTE: LRO requires 2.4.22 or later kernel version.

  IGB_LRO is a compile time flag. The user can enable it at compile 
  time to add support for LRO from the driver. The flag is used by adding 
  CFLAGS_EXTRA="-DIGB_LRO" to the make file when it's being compiled. 

     make CFLAGS_EXTRA="-DIGB_LRO" install

  You can verify that the driver is using LRO by looking at these counters in 
  ethtool:

  lro_aggregated - count of total packets that were combined
  lro_flushed - counts the number of packets flushed out of LRO
  lro_recycled - reflects the number of buffers returned to the ring from 
  recycling

  NOTE: IPv6 and UDP are not supported by LRO.

  
  IEEE 1588 Precision Time Protocol (PTP) Hardware Clock (PHC)
  ---

  Precision Time Protocol (PTP) is an implementation of the IEEE 1588
  specification allowing network cards to synchronize their clocks over a 
  PTP-enabled network. It works through a series of synchronization and delay
  notification transactions that allow a software daemon to implement a PID
  controller to synchronize the network card clocks.
  
  NOTE: PTP requires 3.0.0 or later kernel version that has PTP support
        enabled in the kernel and a user-space software daemon.
  
  IGB_PTP is a compile time flag. The user can enable it at compile time to add
  support for PTP from the driver. The flag is used by adding
  CFLAGS_EXTRA="-DIGB_PTP" to the make file when it's being compiled.

     make CFLAGS_EXTRA="-DIGB_PTP" install

  Please note that the driver will fail to compile if your kernel does not
  support PTP.
  
  You can verify that the driver is using PTP by looking at the system log to
  see whether a PHC was attempted to be registered or not. If you have a kernel
  and version of ethtool with PTP support, you can check the PTP support in the
  driver by executing:

     ethtool -T ethX


  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.

  
Known Issues/Troubleshooting
============================

Hardware Issues:
----------------
For known hardware and troubleshooting issues, either refer to the "Release 
Notes" in your User Guide, or for more detailed information, go to the 
following website:

    http://www.intel.com

In the search box enter your devices controller ID followed by "spec update" 
(i.e., 82599 spec update). The spec update file has complete information on
known hardware issues.

Software Issues:
----------------

  NOTE: After installing the driver, if your Intel Ethernet Network Connection
  is not working, verify that you have installed the correct driver.

  Using the igb driver on 2.4 or older 2.6 based kernels
  ------------------------------------------------------
  Due to limited support for PCI-Express in 2.4 kernels and older 2.6 kernels,
  the igb driver may run into interrupt related problems on some systems, 
  such as no link or hang when bringing up the device.

  We recommend the newer 2.6 based kernels, as these kernels correctly
  configure the PCI-Express configuration space of the adapter and all
  intervening bridges. If you are required to use a 2.4 kernel, use a 2.4 kernel 
  newer than 2.4.30. For 2.6 kernels we recommend using the 2.6.21 kernel or 
  newer.

  Alternatively, on 2.6 kernels you may disable MSI support in the kernel by 
  booting with the "pci=nomsi" option or permanently disable MSI support in 
  your kernel by configuring your kernel with CONFIG_PCI_MSI unset.

  Intel(R) Active Management Technology 2.0, 2.1, 2.5 not supported in 
  conjunction with Linux driver
  ---------------------------------------------------------------------

  Driver Compilation
  ------------------
  When trying to compile the driver by running make install, the following
  error may occur:

    "Linux kernel source not configured - missing version.h"

  To solve this issue, create the version.h file by going to the Linux source
  tree and entering:

    make include/linux/version.h.

  Performance Degradation with Jumbo Frames
  -----------------------------------------
  Degradation in throughput performance may be observed in some Jumbo frames 
  environments. If this is observed, increasing the application's socket buffer
  size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values may help.
  See the specific application manual and 
  /usr/src/linux*/Documentation/networking/ip-sysctl.txt for more details.

  Jumbo Frames on Foundry BigIron 8000 switch
  -------------------------------------------
  There is a known issue using Jumbo frames when connected to a Foundry
  BigIron 8000 switch.  This is a 3rd party limitation.  If you experience
  loss of packets, lower the MTU size.

  Multiple Interfaces on Same Ethernet Broadcast Network
  ------------------------------------------------------
  Due to the default ARP behavior on Linux, it is not possible to have
  one system on two IP networks in the same Ethernet broadcast domain
  (non-partitioned switch) behave as expected.  All Ethernet interfaces
  will respond to IP traffic for any IP address assigned to the system.
  This results in unbalanced receive traffic.

  If you have multiple interfaces in a server, either turn on ARP
  filtering by entering:

    echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter
  (this only works if your kernel's version is higher than 2.4.5),

  NOTE: This setting is not saved across reboots.  The configuration
  change can be made permanent by adding the line:
    net.ipv4.conf.all.arp_filter = 1
  to the file /etc/sysctl.conf

      or,

  install the interfaces in separate broadcast domains (either in
  different switches or in a switch partitioned to VLANs).

  Disable rx flow control with ethtool
  ------------------------------------
  In order to disable receive flow control using ethtool, you must turn
  off auto-negotiation on the same command line.

  For example:

   ethtool -A eth? autoneg off rx off

  Unplugging network cable while ethtool -p is running
  ----------------------------------------------------
  In kernel versions 2.5.50 and later (including 2.6 kernel), unplugging 
  the network cable while ethtool -p is running will cause the system to 
  become unresponsive to keyboard commands, except for control-alt-delete.  
  Restarting the system appears to be the only remedy.

  Trouble passing traffic with on ports 1 and 2 using RHEL3
  ---------------------------------------------------------
  There is a known hardware compatibility issue on some systems with RHEL3 
  kernels. Traffic on ports 1 and 2 may be slower than expected and ping times
  higher than expected. 

  This issue MAY be resolved by updating to the latest kernel and BIOS. You can 
  check your system's BIOS by downloading the Linux Firmware Developer Kit that 
  can be obtained at http://www.linuxfirmwarekit.org/

  Do Not Use LRO When Routing Packets
  -----------------------------------
  Due to a known general compatibility issue with LRO and routing, do not use
  LRO when routing packets.

  Build error with Asianux 3.0 - redefinition of typedef 'irq_handler_t'
  ---------------------------------------------------------------------
  Some systems may experience build issues due to redefinition of irq_handler_t.  
  To resolve this issue build the driver (step 4 above) using the command:

    make CFLAGS_EXTRA=-DAX_RELEASE_CODE=1 install

  MSI-X Issues with Kernels between 2.6.19 - 2.6.21 (inclusive)
  -------------------------------------------------------------
  Kernel panics and instability may be observed on any MSI-X hardware if you 
  use irqbalance with kernels between 2.6.19 and 2.6.21. If such problems are 
  encountered, you may disable the irqbalance daemon or upgrade to a newer 
  kernel.

  Rx Page Allocation Errors
  -------------------------
  Page allocation failure. order:0 errors may occur under stress with kernels 
  2.6.25 and above. This is caused by the way the Linux kernel reports this 
  stressed condition.

  Under Redhat 5.4-GA - System May Crash when Closing Guest OS Window after 
  Loading/Unloading Physical Function (PF) Driver
  -------------------------------------------------------------------------
  Do not remove the igb driver from Dom0 while Virtual Functions (VFs) are 
  assigned to guests. VFs must first use the xm "pci-detach" command to 
  hot-plug the VF device out of the VM it is assigned to or else shut down the
  VM.

  SLES10 SP3 random system panic when reloading driver
  ---------------------------------------------------
  This is a known SLES-10 SP3 issue. After requesting interrupts for MSI-X 
  vectors, system may panic. 

  Currently the only known workaround is to build the drivers with 
  CFLAGS_EXTRA=-DDISABLE_PCI_MSI if the driver need to be loaded/unloaded.
  Otherwise the driver can be loaded once and will be safe, but unloading it 
  will lead to the issue.

  Enabling SR-IOV in a 32-bit Microsoft* Windows* Server 2008 Guest OS using
  Intel (R) 82576-based GbE or Intel (R) 82599-based 10GbE controller under KVM
  -----------------------------------------------------------------------------
  KVM Hypervisor/VMM supports direct assignment of a PCIe device to a VM.  This 
  includes traditional PCIe devices, as well as SR-IOV-capable devices using
  Intel 82576-based and 82599-based controllers.

  While direct assignment of a PCIe device or an SR-IOV Virtual Function (VF)
  to a Linux-based VM running 2.6.32 or later kernel works fine, there is a
  known issue with Microsoft Windows Server 2008 VM that results in a "yellow 
  bang" error. This problem is within the KVM VMM itself, not the Intel driver,
  or the SR-IOV logic of the VMM, but rather that KVM emulates an older CPU 
  model for the guests, and this older CPU model does not support MSI-X
  interrupts, which is a requirement for Intel SR-IOV.  

  If you wish to use the Intel 82576 or 82599-based controllers in SR-IOV mode
  with KVM and a Microsoft Windows Server 2008 guest try the following 
  workaround. The workaround is to tell KVM to emulate a different model of CPU
  when using qemu to create the KVM guest: 

       "-cpu qemu64,model=13"

  Host may reboot after removing PF when VF is active in guest
  ------------------------------------------------------------
  Using kernel versions earlier than 3.2, do not unload the PF driver with 
  active VFs. Doing this will cause your VFs to stop working until you reload
  the PF driver and may cause a spontaneous reboot of your system.


Support
=======

For general information, go to the Intel support website at:

    www.intel.com/support/

or the Intel Wired Networking project hosted by Sourceforge at:

    http://sourceforge.net/projects/e1000

If an issue is identified with the released source code on the supported
kernel with a supported adapter, email the specific information related
to the issue to e1000-devel@lists.sf.net

License
=======

Intel Gigabit Linux driver.
Copyright(c) 1999 - 2012 Intel Corporation.

This program is free software; you can redistribute it and/or modify it
under the terms and conditions of the GNU General Public License,
version 2, as published by the Free Software Foundation.

This program is distributed in the hope it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.

The full GNU General Public License is included in this distribution in
the file called "COPYING".

Trademarks
==========

Intel, Itanium, and Pentium are trademarks or registered trademarks of
Intel Corporation or its subsidiaries in the United States and other
countries.

* Other names and brands may be claimed as the property of others.
