Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial

[mirror_ubuntu-artful-kernel.git] / Documentation / networking / e1000.txt

Linux* Base Driver for the Intel(R) PRO/1000 Family of Adapters
===============================================================

November 15, 2005


Contents
========

- In This Release
- Identifying Your Adapter
- Command Line Parameters
- Speed and Duplex Configuration
- Additional Configurations
- Known Issues
- Support


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

This file describes the Linux* Base Driver for the Intel(R) PRO/1000 Family
of Adapters.  This driver includes support for Itanium(R)2-based systems.

For questions related to hardware requirements, refer to the documentation
supplied with your Intel PRO/1000 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.


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/network/adapter/pro100/21397.htm

For the latest Intel network drivers for Linux, refer to the following
website. In the search field, enter your adapter name or type, or use the
networking link on the left to search for your adapter:

    http://downloadfinder.intel.com/scripts-df/support_intel.asp


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 or insmod
command using this syntax:

     modprobe e1000 [<option>=<VAL1>,<VAL2>,...]

     insmod e1000 [<option>=<VAL1>,<VAL2>,...]

For example, with two PRO/1000 PCI adapters, entering:

     insmod e1000 TxDescriptors=80,128

loads the e1000 driver with 80 TX descriptors for the first adapter and 128
TX descriptors for the second adapter.

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,
        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.


AutoNeg
-------
(Supported only on adapters with copper connections)
Valid Range:   0x01-0x0F, 0x20-0x2F
Default Value: 0x2F

This parameter is a bit mask that specifies which speed and duplex
settings the board advertises. When this parameter is used, the Speed
and Duplex parameters must not be specified.

NOTE:  Refer to the Speed and Duplex section of this readme for more
       information on the AutoNeg parameter.


Duplex
------
(Supported only on adapters with copper connections)
Valid Range:   0-2 (0=auto-negotiate, 1=half, 2=full)
Default Value: 0

Defines the direction in which data is allowed to flow. Can be either
one or two-directional. If both Duplex and the link partner are set to
auto-negotiate, the board auto-detects the correct duplex. If the link
partner is forced (either full or half), Duplex defaults to half-duplex.


FlowControl
----------
Valid Range:   0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx)
Default Value: Reads flow control settings from the EEPROM

This parameter controls the automatic generation(Tx) and response(Rx)
to Ethernet PAUSE frames.


InterruptThrottleRate
---------------------
(not supported on Intel 82542, 82543 or 82544-based adapters)
Valid Range:   100-100000 (0=off, 1=dynamic)
Default Value: 8000

This value represents the maximum number of interrupts per second the
controller generates. InterruptThrottleRate is another setting used in
interrupt moderation. Dynamic mode uses a heuristic algorithm to adjust
InterruptThrottleRate based on the current traffic load.

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.

CAUTION:  If you are using the Intel PRO/1000 CT Network Connection
          (controller 82547), setting InterruptThrottleRate to a value
          greater than 75,000, may hang (stop transmitting) adapters
          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 InterruptThrottleRate is set no greater
          than 75,000 and is not set to 0.

NOTE:  When e1000 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:

           insmod e1000.o 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.


RxDescriptors
-------------
Valid Range:   80-256 for 82542 and 82543-based adapters
               80-4096 for all other supported adapters
Default Value: 256

This value specifies the number of receive descriptors allocated by the
driver. Increasing this value allows the driver to buffer more incoming
packets.  Each descriptor is 16 bytes.  A receive buffer is also
allocated for each descriptor and is 2048.


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
-------------
(This parameter is supported only on 82540, 82545 and later adapters.)
Valid Range:   0-65535 (0=off)
Default Value: 128

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.


Speed
-----
(This parameter is supported only on adapters with copper connections.)
Valid Settings: 0, 10, 100, 1000
Default Value:  0 (auto-negotiate at all supported speeds)

Speed forces the line speed to the specified value in megabits per second
(Mbps). If this parameter is not specified or is set to 0 and the link
partner is set to auto-negotiate, the board will auto-detect the correct
speed. Duplex should also be set when Speed is set to either 10 or 100.


TxDescriptors
-------------
Valid Range:   80-256 for 82542 and 82543-based adapters
               80-4096 for all other supported adapters
Default Value: 256

This value is the number of transmit descriptors allocated by the driver.
Increasing this value allows the driver to queue more transmits. Each
descriptor is 16 bytes.

NOTE:  Depending on the available system resources, the request for a
       higher number of transmit descriptors may be denied.  In this case,
       use a lower number.


TxIntDelay
----------
Valid Range:   0-65535 (0=off)
Default Value: 64

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
-------------
(This parameter is supported only on 82540, 82545 and later adapters.)
Valid Range:   0-65535 (0=off)
Default Value: 64

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.

XsumRX
------
(This parameter is NOT supported on the 82542-based adapter.)
Valid Range:   0-1
Default Value: 1

A value of '1' indicates that the driver should enable IP checksum
offload for received packets (both UDP and TCP) to the adapter hardware.


Speed and Duplex Configuration
==============================

Three keywords are used to control the speed and duplex configuration.
These keywords are Speed, Duplex, and AutoNeg.

If the board uses a fiber interface, these keywords are ignored, and the
fiber interface board only links at 1000 Mbps full-duplex.

For copper-based boards, the keywords interact as follows:

  The default operation is auto-negotiate. The board advertises all
  supported speed and duplex combinations, and it links at the highest
  common speed and duplex mode IF the link partner is set to auto-negotiate.

  If Speed = 1000, limited auto-negotiation is enabled and only 1000 Mbps
  is advertised (The 1000BaseT spec requires auto-negotiation.)

  If Speed = 10 or 100, then both Speed and Duplex should be set. Auto-
  negotiation is disabled, and the AutoNeg parameter is ignored. Partner
  SHOULD also be forced.

The AutoNeg parameter is used when more control is required over the
auto-negotiation process.  It should be used when you wish to control which
speed and duplex combinations are advertised during the auto-negotiation
process.

The parameter may be specified as either a decimal or hexidecimal value as
determined by the bitmap below.

Bit position   7      6      5       4       3      2      1       0
Decimal Value  128    64     32      16      8      4      2       1
Hex value      80     40     20      10      8      4      2       1
Speed (Mbps)   N/A    N/A    1000    N/A     100    100    10      10
Duplex                       Full            Full   Half   Full    Half

Some examples of using AutoNeg:

  modprobe e1000 AutoNeg=0x01 (Restricts autonegotiation to 10 Half)
  modprobe e1000 AutoNeg=1 (Same as above)
  modprobe e1000 AutoNeg=0x02 (Restricts autonegotiation to 10 Full)
  modprobe e1000 AutoNeg=0x03 (Restricts autonegotiation to 10 Half or 10 Full)
  modprobe e1000 AutoNeg=0x04 (Restricts autonegotiation to 100 Half)
  modprobe e1000 AutoNeg=0x05 (Restricts autonegotiation to 10 Half or 100
  Half)
  modprobe e1000 AutoNeg=0x020 (Restricts autonegotiation to 1000 Full)
  modprobe e1000 AutoNeg=32 (Same as above)

Note that when this parameter is used, Speed and Duplex must not be specified.

If the link partner is forced to a specific speed and duplex, then this
parameter should not be used.  Instead, use the Speed and Duplex parameters
previously mentioned to force the adapter to the same speed and duplex.


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 Intel PRO/1000 Family of Adapters is e1000.

  As an example, if you install the e1000 driver for two PRO/1000 adapters
  (eth0 and eth1) and set the speed and duplex to 10full and 100half, add
  the following to modules.conf or modprobe.conf:

       alias eth0 e1000
       alias eth1 e1000
       options e1000 Speed=10,100 Duplex=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
  ------------

  The driver supports Jumbo Frames for all adapters except 82542 and
  82573-based adapters. 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 16110. This value coincides
    with the maximum Jumbo Frames size of 16128.
  - Using Jumbo Frames at 10 or 100 Mbps may result in poor performance or
    loss of link.
  - Some Intel gigabit adapters that support Jumbo Frames have a frame size
    limit of 9238 bytes, with a corresponding MTU size limit of 9216 bytes.
    The adapters with this limitation are based on the Intel 82571EB and
    82572EI controllers, which correspond to these product names: