PF_RING-5.6.0/drivers/DNA/e1000e-2.0.0.1-DNA/README

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

January 5, 2012

Contents
========

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

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

This file describes the e1000e Linux* Base Driver for Intel Ethernet Network
Connection.  This driver supports kernel versions 2.4.x and 2.6.x.  This 
driver includes support for Itanium(R)2-based systems.

NOTE: The 82546GB part requires the e1000 driver, not the e1000e driver.
 
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 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.

NOTE: The Intel(R) 82562v 10/100 Network Connection only provides 10/100
support.

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

Upgrading
=========

If you currently have the e1000 driver installed and need to install e1000e,
perform the following:

 - If your version of e1000 is 7.6.15.5 or less, upgrade to e1000 version 8.x,
   using the instructions in the e1000 README. 
 - Install the e1000e driver using the instructions in the Building and 
   Installation section below.
 - Modify /etc/modprobe.conf to point your PCIe devices to use the new e1000e 
   driver using alias ethX e1000e, or use your distribution's specific method 
   for configuring network adapters like RedHat's setup/system-config-network
   or SuSE's yast2.

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/e1000e or /usr/local/src/e1000e.

2. Untar/unzip archive:

     tar zxf e1000e-x.x.x.tar.gz

3. Change to the driver src directory:

     cd e1000e-x.x.x/src/

4. Compile the driver module:

     # make install

   The binary will be installed as:

     /lib/modules/<KERNEL VERSION>/kernel/drivers/net/e1000e/e1000e.[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 either the insmod or modprobe command:

     modprobe e1000e

     insmod e1000e

   Note that for 2.6 kernels the insmod command can be used if the full
   path to the driver module is specified.  For example:

     insmod /lib/modules/<KERNEL VERSION>/kernel/drivers/net/e1000e/e1000e.ko

   With 2.6 based kernels also make sure that older e1000e drivers are 
   removed from the kernel, before loading the new module:

     rmmod e1000e; modprobe e1000e

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 e1000e device, then this workaround
may be necessary.

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 e1000e [<option>=<VAL1>,<VAL2>,...]

The default value for each parameter is generally the recommended setting,
unless otherwise noted.

NOTES:  For more information about the InterruptThrottleRate,
        RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
        parameters, 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:   0,1,3,4, 100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
                                    4=simplified balancing)
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 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".

In simplified mode the interrupt rate is based on the ratio of tx and
rx traffic.  If the bytes per second rate is approximately equal, the
interrupt rate will drop as low as 2000 interrupts per second.  If the
traffic is mostly transmit or mostly receive, the interrupt rate could
be as high as 8000.

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:  InterruptThrottleRate takes precedence over the TxAbsIntDelay and
       RxAbsIntDelay parameters.  In other words, minimizing the receive
       and/or transmit absolute delays does not force the controller to
       generate more interrupts than what the Interrupt Throttle Rate
       allows.

NOTE:  When e1000e 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 e1000e 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
       RX_POLLING (NAPI) and default driver settings.

RxIntDelay
----------
Valid Range:   0-65535 (0=off)
Default Value: 0

This value delays the generation of receive interrupts in units of 1.024
microseconds.  Receive interrupt reduction can improve CPU efficiency if
properly tuned for specific network traffic.  Increasing this value adds
extra latency to frame reception and can end up decreasing the throughput
of TCP traffic.  If the system is reporting dropped receives, this value
may be set too high, causing the driver to run out of available receive
descriptors.

CAUTION:  When setting RxIntDelay to a value other than 0, adapters may
          hang (stop transmitting) under certain network conditions.  If
          this occurs a NETDEV WATCHDOG message is logged in the system
          event log.  In addition, the controller is automatically reset,
          restoring the network connection.  To eliminate the potential
          for the hang ensure that RxIntDelay is set to 0.

RxAbsIntDelay
-------------
Valid Range:   0-65535 (0=off)
Default Value: 8

This value, in units of 1.024 microseconds, limits the delay in which a
receive interrupt is generated.  Useful only if RxIntDelay is non-zero,
this value ensures that an interrupt is generated after the initial
packet is received within the set amount of time.  Proper tuning,
along with RxIntDelay, may improve traffic throughput in specific network
conditions.

TxIntDelay
----------
Valid Range:   0-65535 (0=off)
Default Value: 8

This value delays the generation of transmit interrupts in units of
1.024 microseconds.  Transmit interrupt reduction can improve CPU
efficiency if properly tuned for specific network traffic.  If the
system is reporting dropped transmits, this value may be set too high
causing the driver to run out of available transmit descriptors.

TxAbsIntDelay
-------------
Valid Range:   0-65535 (0=off)
Default Value: 32

This value, in units of 1.024 microseconds, limits the delay in which a
transmit interrupt is generated.  Useful only if TxIntDelay is non-zero,
this value ensures that an interrupt is generated after the initial
packet is sent on the wire within the set amount of time.  Proper tuning,
along with TxIntDelay, may improve traffic throughput in specific
network conditions.

copybreak
---------
Valid Range:   0-xxxxxxx (0=off)
Default Value: 256
Usage: insmod e1000e.ko copybreak=128

Driver copies all packets below or equaling this size to a fresh rx
buffer before handing it up the stack.

This parameter is different than other parameters, in that it is a
single (not 1,1,1 etc.) parameter applied to all driver instances and
it is also available during runtime at 
/sys/module/e1000e/parameters/copybreak

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

Allows Phy to turn off in lower power states. The user can turn off
this parameter in supported chipsets.

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

This workaround skips resetting the Phy at shutdown for the initial
silicon releases of ICH8 systems.

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

Allows changing the interrupt mode at module load time, without requiring a
recompile. If the driver load fails to enable a specific interrupt mode, the
driver will try other interrupt modes, from least to most compatible.  The 
interrupt order is MSI-X, MSI, Legacy.  If specifying MSI (IntMode=1) 
interrupts, only MSI and Legacy will be attempted.

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

Strip the CRC from received packets before sending up the network stack.  If 
you have a machine with a BMC enabled but cannot receive IPMI traffic after
loading or enabling the driver, try disabling this feature.

EEE
---
Valid Range:    0-1
Default Value:    1 (enabled for parts supporting EEE)
 
This option allows for the ability of IEEE802.3az (a.k.a. Energy Efficient 
Ethernet or EEE) to be advertised to the link partner on parts supporting EEE.
EEE saves energy by putting the device into a low-power state when the link is
idle, but only when the link partner also supports EEE and after the feature 
has been enabled during link negotiation.  It is not necessary to disable the 
advertisement of EEE when connected with a link partner that does not support EEE.

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 insmod/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. 
 

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 e1000e.

  As an example, if you install the e1000e 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 e1000e
       alias eth1 e1000e
       options e1000e 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.
    
  - The following adapters limit Jumbo Frames sized packets to a maximum of
    4088 bytes:
     Intel(R) 82578DM Gigabit Network Connection
     Intel(R) 82577LM Gigabit Network Connection 

  - The following adapters do not support Jumbo Frames:
     Intel(R) PRO/1000 Gigabit Server Adapter
     Intel(R) PRO/1000 PM Network Connection
     Intel(R) 82562V 10/100 Network Connection
     Intel(R) 82566DM Gigabit Network Connection
     Intel(R) 82566DC Gigabit Network Connection
     Intel(R) 82566MM Gigabit Network Connection
     Intel(R) 82566MC Gigabit Network Connection
     Intel(R) 82562GT 10/100 Network Connection
     Intel(R) 82562G 10/100 Network Connection
     Intel(r) 82566DC-2 Gigabit Network Connection
     Intel(R) 82562V-2 10/100 Network Connection
     Intel(R) 82562G-2 10/100 Network Connection
     Intel(R) 82562GT-2 10/100 Network Connection
     Intel(R) 82578DC Gigabit Network Connection
     Intel(R) 82567V-3 Gigabit Network Connection

  - Jumbo Frames cannot be configured on an 82579-based Network device, if 
    MACSec is enabled on the system.

  ethtool
  -------
  The driver utilizes the ethtool interface for driver configuration and
  diagnostics, as well as displaying statistical information.  ethtool
  version 3 or later is required for this functionality, although we 
  strongly recommend downloading the latest version at:

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

  NOTE: When validating enable/disable tests on some parts (82578, for example)
  you need to add a few seconds between tests when working with ethtool.

  Speed and Duplex
  ----------------
  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:
  http://sourceforge.net/projects/gkernel.

  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 e1000e driver must be
  loaded when shutting down or rebooting the system.

  Wake On LAN is only supported on port A for the following devices:
  Intel(R) PRO/1000 PT Dual Port Network Connection
  Intel(R) PRO/1000 PT Dual Port Server Connection
  Intel(R) PRO/1000 PT Dual Port Server Adapter
  Intel(R) PRO/1000 PF Dual Port Server Adapter
  Intel(R) PRO/1000 PT Quad Port Server Adapter
  Intel(R) Gigabit PT Quad Port Server ExpressModule 

  NAPI
  ----
  NAPI (Rx polling mode) is supported in the e1000e driver.  NAPI is enabled
  by default.

  To disable NAPI, compile the driver module, passing in a configuration option:

       # make CFLAGS_EXTRA=-DE1000E_NO_NAPI install

  See ftp://robur.slu.se/pub/Linux/net-development/NAPI/usenix-paper.tgz for 
  more information on NAPI.


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.

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

  Detected Tx Unit Hang in Quad Port Adapters
  -------------------------------------------
  In some cases ports 3 and 4 don't pass traffic and report 'Detected Tx Unit
  Hang' followed by 'NETDEV WATCHDOG: ethX: transmit timed out' errors. Ports 
  1 and 2 don't show any errors and will pass traffic.

  This issue MAY be resolved by updating to the latest kernel and BIOS. The 
  user is encouraged to run an OS that fully supports MSI interrupts. You can 
  check your system's BIOS by downloading the Linux Firmware Developer Kit 
  that can be obtained at http://www.linuxfirmwarekit.org/

  Adapters with 4 ports behind a PCIe bridge 
  ------------------------------------------
  Adapters that have 4 ports behind a PCIe bridge may be incompatible with 
  some systems. The user should run the Linux firmware kit from 2686434
  http://www.linuxfirmwarekit.org to test their BIOS, if they have interrupt or 
  "missing interface" problems, especially with older kernels.

  82573(V/L/E) TX Unit Hang Messages
  ----------------------------------
  Several adapters with the 82573 chipset display "TX unit hang" messages 
  during normal operation with the e1000e driver. The issue appears both with 
  TSO enabled and disabled, and is caused by a power management function that 
  is enabled in the EEPROM. Early releases of the chipsets to vendors had the 
  EEPROM bit that enabled the feature. After the issue was discovered newer 
  adapters were released with the feature disabled in the EEPROM. 

  If you encounter the problem in an adapter, and the chipset is an 82573-based
  one, you can verify that your adapter needs the fix by using ethtool: 

  # ethtool -e eth0
  Offset          Values
  ------          ------
  0x0000          00 12 34 56 fe dc 30 0d 46 f7 f4 00 ff ff ff ff
  0x0010          ff ff ff ff 6b 02 8c 10 d9 15 8c 10 86 80 de 83
                                                           ^^
  The value at offset 0x001e (de) has bit 0 unset. This enables the problematic 
  power saving feature. In this case, the EEPROM needs to read "df" at offset 
  0x001e. 

  A one-time EEPROM fix is available as a shell script. This script will verify 
  that the adapter is applicable to the fix and if the fix is needed or not. If 
  the fix is required, it applies the change to the EEPROM and updates the 
  checksum. The user must reboot the system after applying the fix if changes 
  were made to the EEPROM. 

  Example output of the script: 

  # bash fixeep-82573-dspd.sh eth0
  eth0: is a "82573E Gigabit Ethernet Controller"
  This fixup is applicable to your hardware
  executing command: ethtool -E eth0 magic 0x109a8086 offset 0x1e value 0xdf
  Change made. You *MUST* reboot your machine before changes take effect!

  The script can be downloaded at 
  http://e1000.sourceforge.net/files/fixeep-82573-dspd.sh

  Dropped Receive Packets on Half-duplex 10/100 Networks
  ------------------------------------------------------
  If you have an Intel PCI Express adapter running at 10mbps or 100mbps, half-
  duplex, you may observe occasional dropped receive packets.  There are no
  workarounds for this problem in this network configuration.  The network must
  be updated to operate in full-duplex, and/or 1000mbps only.

  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.

  Allocating Rx Buffers when Using Jumbo Frames 
  ---------------------------------------------
  Allocating Rx buffers when using Jumbo Frames on 2.6.x kernels may fail if 
  the available memory is heavily fragmented. This issue may be seen with PCI-X 
  adapters or with packet split disabled. This can be reduced or eliminated 
  by changing the amount of available memory for receive buffer allocation, by
  increasing /proc/sys/vm/min_free_kbytes. 

  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.

  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.
  
  Network throughput degradation observed with Onboard video versus add-in 
  Video Card on  82579LM Gigabit Network Connection when used with some older
  kernels.
  ------------------------------------------------------------------------
  This issue can be worked around by specifying "pci=nommconf" in the kernel
  boot parameter or by using another kernel boot parameter 
  "memmap=128M$0x100000000" which marks 128 MB region at 4GB as reserved and
  therefore OS won't use these RAM pages.

  This issue is fixed in kernel version 2.6.21, where the kernel tries to 
  dynamically find out the mmconfig size by looking at the number of buses 
  that the mmconfig segment maps to.

  This issue won't be seen on 32bit version of EL5, as in that case, the kernel 
  sees that RAM is located around the 256MB window and avoids using the 
  mmconfig space.

  Activity LED blinks unexpectedly
  --------------------------------
  If a system based on the 82577, 82578, or 82579 controller is connected
  to a hub, the Activity LED will blink for all network traffic present on
  the hub. Connecting the system to a switch or router will filter out most
  traffic not addressed to the local port.

  Link may take longer than expected
  -----------------------------------------------------------------------
  With some Phy and switch combinations, link can take longer than expected.  
  This can be an issue on Linux distributions that timeout when checking for 
  link prior to acquiring a DHCP address; however there is usually a way to 
  work around this (e.g. set LINKDELAY in the interface configuration on RHEL).

  Tx flow control is disabled by default on 82577 and 82578-based adapters
  ------------------------------------------------------------------------

  Possible performance degradation on certain 82566 and 82577 devices
  ------------------------------------------------------------------- 
  Internal stress testing with jumbo frames shows the reliability on some
  82566 and 82567 devices is improved in certain corner cases by disabling the
  Early Receive feature. Doing so can impact Tx performance. To reduce the
  impact, the packet buffer sizes and relevant flow control settings are
  modified accordingly.

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.