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linux/Documentation/networking/e1000.txt
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2 
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

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Linux* Base Driver for the Intel(R) PRO/1000 Family of Adapters
===============================================================
November 17, 2004
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, version 5.x.x.
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.
Native VLANs are now available with supported kernels.
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. Also, if the driver is statically built into the
kernel, the driver is loaded with the default values for all the parameters.
Ethtool can be used to change some of the parameters at runtime.
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 (adapters using copper connections only)
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 (adapters using copper connections only)
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: Read flow control settings from the EEPROM
This parameter controls the automatic generation(Tx) and response(Rx) to
Ethernet PAUSE frames.
InterruptThrottleRate
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.
Un-supported Adapters: InterruptThrottleRate is NOT supported by 82542, 82543
or 82544-based adapters.
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 is 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 allocated for each
descriptor and can either be 2048 or 4096 bytes long, depending on the MTU
setting. An incoming packet can span one or more receive descriptors.
The maximum MTU size is 16110.
NOTE: MTU designates the frame size. It only needs to be set for Jumbo
Frames.
NOTE: Depending on the available system resources, the request for a
higher number of receive descriptors may be denied. In this case,
use a lower number.
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 (82540, 82545 and later adapters only)
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 (adapters using copper connections only)
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 (82540, 82545 and later adapters only)
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 (not available 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. When this parameter is used, Speed and Duplex parameters
must not be specified. The following table describes supported values for the
AutoNeg parameter:
Speed (Mbps) 1000 100 100 10 10
Duplex Full Full Half Full Half
Value (in base 16) 0x20 0x08 0x04 0x02 0x01
Example: insmod e1000 AutoNeg=0x03, loads e1000 and specifies (10 full duplex,
10 half duplex) for negotiation with the peer.
Note that setting AutoNeg does not guarantee that the board will link at the
highest specified speed or duplex mode, but the board will link at the
highest possible speed/duplex of the link partner IF the link partner is also
set to auto-negotiate. If the link partner is forced speed/duplex, the
adapter MUST be forced to the same speed/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 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:
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-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 ethx mtu 9000 up
The maximum MTU setting for Jumbo Frames is 16110. This value coincides
with the maximum Jumbo Frames size of 16128.
NOTE: Jumbo Frames are supported at 1000 Mbps only. Using Jumbo Frames at
10 or 100 Mbps may result in poor performance or loss of link.
NOTE: MTU designates the frame size. To enable Jumbo Frames, increase the
MTU size on the interface beyond 1500.
Ethtool
-------
The driver utilizes the ethtool interface for driver configuration and
diagnostics, as well as displaying statistical information. Ethtool
version 1.6 or later is required for this functionality.
The latest release of ethtool can be found from
http://sf.net/projects/gkernel.
NOTE: Ethtool 1.6 only supports a limited set of ethtool options. Support
for a more complete ethtool feature set can be enabled by upgrading
ethtool to ethtool-1.8.1.
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 e1000 driver must be
loaded when shutting down or rebooting the system.
NAPI
----
NAPI (Rx polling mode) is supported in the e1000 driver. NAPI is enabled
or disabled based on the configuration of the kernel.
See www.cyberus.ca/~hadi/usenix-paper.tgz for more information on NAPI.
Known Issues
============
Jumbo Frames System Requirement
-------------------------------
Memory allocation failures have been observed on Linux systems with 64 MB
of RAM or less that are running Jumbo Frames. If you are using Jumbo Frames,
your system may require more than the advertised minimum requirement of 64 MB
of system memory.
Support
=======
For general information, go to the Intel support website at:
http://support.intel.com
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 linux.nics@intel.com.
License
=======
This software program is released under the terms of a license agreement
between you ('Licensee') and Intel. Do not use or load this software or any
associated materials (collectively, the 'Software') until you have carefully
read the full terms and conditions of the LICENSE located in this software
package. By loading or using the Software, you agree to the terms of this
Agreement. If you do not agree with the terms of this Agreement, do not
install or use the Software.
* Other names and brands may be claimed as the property of others.
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