i40e Linux* Base Driver for the Intel(R) XL710 Ethernet Controller Family
===============================================================================

===============================================================================

December 16, 2015

===============================================================================

Contents
--------

- Overview
- Identifying Your Adapter
- Building and Installation
- Command Line Parameters
- Intel(R) i40e Ethernet Flow Director
- Additional Features & Configurations
- Known Issues


================================================================================


Important Notes
---------------

Enabling a VF link if the port is disconnected
----------------------------------------------

If the physical function (PF) link is down, you can force link up (from the host
PF) on any virtual functions (VF) bound to the PF. Note that this requires
kernel support (Redhat kernel 3.10.0-327 or newer, upstream kernel 3.11.0 or
newer, and associated iproute2 user space support). If the following command
does not work, it may not be supported by your system. The following command
forces link up on VF 0 bound to PF eth0:
  ip link set eth0 vf 0 state enable


Do not unload port driver if VF with active VM is bound to it
-------------------------------------------------------------

Do not unload a port's driver if a Virtual Function (VF) with an active Virtual
Machine (VM) is bound to it. Doing so will cause the port to appear to hang.
Once the VM shuts down, or otherwise releases the VF, the command will complete.


Configuring SR-IOV for improved network security
------------------------------------------------

In a virtualized environment, on Intel(R) Server Adapters that support SR-IOV,
the virtual function (VF) may be subject to malicious behavior. Software-
generated layer two frames, like IEEE 802.3x (link flow control), IEEE 802.1Qbb
(priority based flow-control), and others of this type, are not expected and
can throttle traffic between the host and the virtual switch, reducing
performance. To resolve this issue, configure all SR-IOV enabled ports for
VLAN tagging. This configuration allows unexpected, and potentially malicious,
frames to be dropped.



Overview
--------

This document describes the i40e Linux* Base Driver
for the XL710 Ethernet Controller Family of Adapters.

The Linux* base driver supports the following kernel versions:
2.6.32 and newer

It includes support for Linux supported x86_64 systems.

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 drivers.

For questions related to hardware requirements, refer to the documentation
supplied with your Intel 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
- Generic Receive Offload

Adapter teaming is implemented using the native Linux Channel bonding
module. This is included in supported Linux kernels.
Channel Bonding documentation can be found in the Linux kernel source:
/documentation/networking/bonding.txt

The driver information previously displayed in the /proc file system is not
supported in this release.

Driver information can be obtained using ethtool, lspci, and ifconfig.
Instructions on updating ethtool can be found in the section Additional 
Configurations later in this document.



Identifying Your Adapter
------------------------
The driver in this release is compatible with XL710 and X710-based Intel
Ethernet Network Connections.

For information on how to identify your adapter, go to the Adapter &
Driver ID Guide at:
http://support.intel.com/support/go/network/adapter/proidguide.htm

For the best performance, make sure the latest NVM/FW is installed on your device
 and that you are using the newest drivers.

For the latest NVM/FW images and Intel network drivers, refer to the
following website and select your adapter.
http://www.intel.com/support


SFP+ Devices with Pluggable Optics
----------------------------------

SR Modules
----------
  Intel	DUAL RATE 1G/10G SFP+ SR (bailed)	E10GSFPSR

LR Modules
---------- 
  Intel	DUAL RATE 1G/10G SFP+ LR (bailed	E10GSFPLR

1G SFP Modules
--------------
The following is a list of 3rd party SFP modules that have received some
testing. Not all modules are applicable to all devices.

Supplier	Type		Part Numbers
Finisar		1000BASE-T	SFP FCLF-8251-3
Kinnex A	1000BASE-T	SFP XSFP-T-RJ12-0101-DLL
Avago		1000BASE-T	SFP ABCU-5710RZ

QSFP+ Modules
-------------
NOTE: Intel branded network adapters based on the X710/XL710 controller
  (for example, Intel(R) Ethernet Converged Network Adapter XL710-Q1) support
  the E40GQSFPLR module. For other connections based on the X710/XL710
  controller, support is dependent on your system board. Please see your vendor
  for details.

  Intel	TRIPLE RATE 1G/10G/40G QSFP+ SR (bailed)	E40GQSFPSR
  Intel	TRIPLE RATE 1G/10G/40G QSFP+ LR (bailed)	E40GQSFPLR
    QSFP+ 1G speed is not supported on XL710 based devices.

X710/XL710 Based SFP+ adapters support passive QSFP+ Direct Attach cables.
Intel recommends using Intel optics and cables. Other modules may function
but are not validated by Intel. Contact Intel for supported media types.


================================================================================


Building and Installation
-------------------------

To build a binary RPM* package of this driver, run 'rpmbuild -tb
i40e-<x.x.x>.tar.gz', where <x.x.x> is the version number for the driver tar file.

NOTES:

- 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 before building.
- 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/i40e' or '/usr/local/src/i40e'.

2. Untar/unzip the archive, where <x.x.x> is the version number for the
   driver tar file:
   tar zxf i40e-<x.x.x>.tar.gz

3. Change to the driver src directory, where <x.x.x> is the version number
   for the driver tar:
   cd i40e-<x.x.x>/src/

4. Compile the driver module:
   # make install
   The binary will be installed as:
   /lib/modules/<KERNEL VERSION>/updates/drivers/net/ethernet/intel/i40e/i40e.ko

   The install location listed above is the default location. This may differ
   for various Linux distributions.

5. Load the module using the modprobe command:
   modprobe <i40e> [parameter=port1_value,port2_value]

   Make sure that any older i40e drivers are removed from the kernel before
   loading the new module:
   rmmod i40e; modprobe i40e

6. Assign an IP address to the interface by entering the following,
   where ethX is the interface name that was shown in dmesg after modprobe:
   
   ip address add <IP_address>/<netmask bits> dev ethX

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>

NOTE:
   For certain distributions like (but not limited to) RedHat Enterprise
   Linux 7 and Ubuntu, once the driver is installed the initrd/initramfs
   file may need to be updated to prevent the OS loading old versions
   of the i40e driver. The dracut utility may be used on RedHat
   distributions:
	# dracut --force
   For Ubuntu:
	# update-initramfs -u


================================================================================


Command Line Parameters
-----------------------
In general, ethtool and other OS specific commands are used to configure user
changeable parameters after the driver is loaded. The i40e driver only supports
the max_vfs kernel parameter on older kernels that do not have the standard
sysfs interface. The only other module parameter supported is the debug
parameter that can control the default logging verbosity of the driver.

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 i40e [<option>=<VAL1>]

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 i40e max_vfs=7

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



max_vfs
-------
Valid Range:
1-32 (X710 based devices)
1-64 (XL710 based devices)

NOTE: This parameter is only used on kernel 3.7.x and below. On kernel 3.8.x
and above, use sysfs to enable VFs. For example:
#echo $num_vf_enabled > /sys/class/net/$dev/device/sriov_numvfs	//enable VFs
#echo 0 > /sys/class/net/$dev/device/sriov_numvfs	//disable VFs

The parameters for the driver are referenced by position. Thus, if you have a
dual port adapter, or more than one adapter in your system, and want N virtual
functions per port, you must specify a number for each port with each parameter
separated by a comma. For example:
  modprobe i40e max_vfs=4,1
NOTE: Caution must be used in loading the driver with these parameters.
Depending on your system configuration, number of slots, etc., it is impossible
to predict in all cases where the positions would be on the command line.
This parameter adds support for SR-IOV. It causes the driver to spawn up to
max_vfs worth of virtual functions.
Some hardware configurations support fewer SR-IOV instances, as the whole
XL710 controller (all functions) is limited to 128 SR-IOV interfaces in total.
NOTE: When SR-IOV 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


Configuring SR-IOV for improved network security
------------------------------------------------

In a virtualized environment, on Intel(R) Server Adapters that support SR-IOV,
the virtual function (VF) may be subject to malicious behavior. Software-
generated layer two frames, like IEEE 802.3x (link flow control), IEEE 802.1Qbb
(priority based flow-control), and others of this type, are not expected and
can throttle traffic between the host and the virtual switch, reducing
performance. To resolve this issue, configure all SR-IOV enabled ports for
VLAN tagging. This configuration allows unexpected, and potentially malicious,
frames to be dropped.


Configuring VLAN tagging on SR-IOV enabled adapter ports
--------------------------------------------------------

To configure VLAN tagging for the ports on an SR-IOV enabled adapter,
use the following command. The VLAN configuration should be done 
before the VF driver is loaded or the VM is booted.

$ ip link set dev <PF netdev id> vf <id> vlan <vlan id>

For example, the following instructions will configure PF eth0 and 
the first VF on VLAN 10.
$ ip link set dev eth0 vf 0 vlan 10
.

Intel(R) Ethernet Flow Director
-------------------------------
NOTE: Flow director parameters are only supported on kernel versions 2.6.30 or
newer.

The Flow Director performs the following tasks:

  - Directs receive packets according to their flows to different queues.
  - Enables tight control on routing a flow in the platform.
  - Matches flows and CPU cores for flow affinity.
  - Supports multiple parameters for flexible flow classification and load
    balancing.

NOTES:

  - The Flow Director is enabled only if the kernel supports multiple
    transmit queues.
  - An included script (set_irq_affinity) automates setting the IRQ to
    CPU affinity.
  - The i40e Linux driver does not support configuration of the mask field.
    It only accepts rules that completely qualify a certain flow type.

ethtool commands:

  - To enable or disable the Flow Director

	# ethtool -K ethX ntuple <on|off>

	When disabling ntuple filters all the user programed filters are flushed
	from the driver cache and hardware. Filters must be re-added if they are
	needed when ntuple is re-enabled.

  - To add a filter that directs packet to queue 2, use -U or -N switch

	# ethtool -N ethX flow-type tcp4 src-ip 192.168.10.1 dst-ip \
	192.168.10.2 src-port 2000 dst-port 2001 action 2 [loc 1]

  - To see the list of filters currently present
	# ethtool <-u|-n> ethX

Application Targeted Routing (ATR) Perfect Filters
--------------------------------------------------
ATR is enabled by default when the kernel is in multiple transmit queue mode.
An ATR flow director filter rule is added when a TCP-IP flow starts and is
deleted when the flow ends. When a TCP-IP Flow Director rule is added from
ethtool (Sideband filter), ATR is turned off by the driver. To re-enable ATR,
the sideband can be disabled with the ethtool -K option. If sideband is
re-enabled after ATR is re-enabled, ATR remains enabled until a TCP-IP flow
is added. When all TCP-IP sideband rules are deleted, ATR is automatically
re-enabled.

Packets that match the ATR rules are counted in fdir_atr_match stats in
ethtool, which also can be used to verify whether ATR rules still exist.

Sideband Perfect Filters
------------------------
Sideband Perfect Filters is an interface for loading the filter table that
funnels all flow into queue_0 unless an alternative queue is specified
using "action." If action is used, any flow that matches the filter criteria
will be directed to the appropriate queue. Rules may be deleted from the
table. This is done via

  ethtool -U ethX delete N

  where N is the rule number to be deleted, as specified in the loc value in
  the filter add command.

  If the queue is defined as -1, the filter drops matching packets. To account
  for Sideband filter matches, the fdir_sb_match stats in ethtool can be used.

  In addition, rx-N.rx_packets shows the number of packets processed by the
  Nth queue.

NOTES:
Receive Packet Steering (RPS) and Receive Flow Steering (RFS) are not compatible
with Flow Director. If Flow Director is enabled, these will be disabled.

The VLAN field for Flow Director is not explicitly supported in the i40e
driver.

When filter rules are added from Sideband or ATR and the Flow Director filter
table is full, the ATR rule is turned off by the driver. Subsequently, the
Sideband filter rule is then turned off. When space becomes available in the
filter table through filter rule deletion (i.e., an ATR rule or Sideband rule
is deleted), the Sideband and ATR rule additions are turned back on.

Occasionally, when the filter table is full, you will notice HW errors when
you try to add new rules. The i40e driver will call for a filter flush and
sideband filter list replay. This will help flush any stale ATR rules and
create space.


================================================================================


Additional Features and 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 Base Driver is i40e.


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 Maximum Transmission Unit
(MTU) to a value larger than the default value of 1500.

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

   ifconfig eth<x> mtu 9000 up

This setting is not saved across reboots. The setting change can be made
permanent by adding 'MTU=9000' to the file:
/etc/sysconfig/network-scripts/ifcfg-eth<x> for RHEL or to the file
/etc/sysconfig/network/<config_file> for SLES.

NOTES:
- The maximum MTU setting for Jumbo Frames is 9706. This value coincides
  with the maximum Jumbo Frames size of 9728 bytes.
- This driver will attempt to use multiple page sized buffers to receive
  each jumbo packet. This should help to avoid buffer starvation issues
  when allocating receive packets.


ethtool
-------
The driver utilizes the ethtool interface for driver configuration and
diagnostics, as well as displaying statistical information. The latest
ethtool version is required for this functionality. Download it at
http://ftp.kernel.org/pub/software/network/ethtool/

Supported ethtool Commands and Options
--------------------------------------
-n --show-nfc
  Retrieves the receive network flow classification configurations.

rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6
  Retrieves the hash options for the specified network traffic type.

-N --config-nfc
  Configures the receive network flow classification.

rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6 m|v|t|s|d|f|n|r...
  Configures the hash options for the specified network traffic type.

  udp4 UDP over IPv4
  udp6 UDP over IPv6

  f Hash on bytes 0 and 1 of the Layer 4 header of the rx packet.
  n Hash on bytes 2 and 3 of the Layer 4 header of the rx packet.


NAPI
----
NAPI (Rx polling mode) is supported in the i40e driver.
For more information on NAPI, see
https://www.linuxfoundation.org/collaborate/workgroups/networking/napi


Flow Control
------------

Ethernet Flow Control (IEEE 802.3x) can be configured with ethtool to enable
receiving and transmitting pause frames for i40e. When transmit is enabled,
pause frames are generated when the receive packet buffer crosses a predefined
threshold. When receive is enabled, the transmit unit will halt for the time
delay specified when a pause frame is received. 

Flow Control is disabled by default.

Use ethtool to change the flow control settings.

ethtool:
ethtool -A eth? autoneg off rx on tx on

NOTE: You must have a flow control capable link partner.


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.
NOTE: This feature can be disabled for a specific Virtual Function (VF).
ip link set <pf dev> vf <vf id> spoofchk {off|on}


Support for UDP RSS
-------------------

This feature adds an ON/OFF switch for hashing over certain flow types. Only
UDP can be turned on. The default setting is enabled .


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

Precision Time Protocol (PTP) is used to synchronize clocks in a computer
network and is supported in the i40e driver.



VXLAN Overlay HW Offloading
---------------------------

Virtual Extensible LAN (VXLAN) allows you to extend an L2 network over an L3
network, which may be useful in a virtualized or cloud environment. Some Intel(R)
Ethernet Network devices perform VXLAN processing, offloading it from the
operating system. This reduces CPU utilization.
 
VXLAN offloading is controlled by the tx and rx checksum offload options
provided by ethtool. That is, if tx checksum offload is enabled, and the adapter
has the capability, VXLAN offloading is also enabled. If rx checksum offload is
enabled, then the VXLAN packets rx checksum will be offloaded, unless the module
parameter vxlan_rx=0,0 was used to specifically disable the VXLAN rx offload.
 
VXLAN Overlay HW Offloading is enabled by default. To view and configure VXLAN
on a VXLAN-overlay offload enabled device, use the following
command:

  # ethtool -k ethX
   (This command displays the offloads and their current state.)

i40e support for VXLAN HW offloading is dependent on
kernel support of the HW offloading features.

For more information on configuring your network for overlay HW offloading
support, refer to the Intel Technical Brief, "Creating Overlay Networks
Using Intel Ethernet Converged Network Adapters" (Intel Networking Division,
August 2013):

http://www.intel.com/content/dam/www/public/us/en/documents/technology-briefs/
overlay-networks-using-converged-network-adapters-brief.pdf


Multiple Functions per Port
---------------------------

On X710/XL710 based adapters that support it, you can set up multiple functions
on each physical port. You configure these functions through the System
Setup/BIOS.

Minimum TX Bandwidth is the guaranteed minimum data transmission bandwidth, as
a percentage of the full physical port link speed, that the partition will
receive. The bandwidth the partition is awarded will never fall below the level
you specify here.

The range for the minimum bandwidth values is:
1 to ((100 minus # of partitions on the physical port) plus 1)
For example, if a physical port has 4 partitions, the range would be
1 to ((100 - 4) + 1 = 97)

The Maximum Bandwidth percentage represents the maximum transmit
bandwidth allocated to the partition as a percentage of the full physical port
link speed. The accepted range of values is 1-100. The value can be used as a
limiter, should you chose that any one particular function not be able to
consume 100% of a port's bandwidth (should it be available). The sum of
all the values for Maximum Bandwidth is not restricted, because no more than
100% of a port's bandwidth can ever be used.

Once the initial configuration is complete, you can set different
bandwidth allocations on each function as follows:
1. Make a new directory named /config
2. edit etc/fstab to include:

	configfs /config configfs defaults

3. Mount /config
4. Load (or reload) the i40e driver
5. Make a new directory under config/i40e for each partition upon which you
   wish to configure the bandwidth.
6. The following files will appear under the config/partition directory:
   - max_bw
   - min_bw
   - commit
   - ports
   - partitions
   read from max_bw to get display the current maximum bandwidth setting.
   write to max_bw to set the maximum bandwidth for this function.
   read from min_bw to display the current minimum bandwidth setting.
   Write to min_bw to set the minimum bandwidth for this function.
   Write a '1' to commit to save your changes.

Notes: -commit is write only. Attempting to read it will result in an
	 error.
	-Writing to commit is only supported on the first function of
	 a given port. Writing to a subsequent function will result in an
	 error.
	-Oversubscribing the minimum bandwidth is not supported. The underlying
	 device's NVM will set the minimum bandwidth to supported values in an
	 indeterminate manner. Remove all of the directories under config and
	 reload them to see what the actual values are.
	-To unload the driver you must first remove the directories created in
	 step 5, above.

Example of Setting the minimum and maximum bandwidth (assume there are four
function on the port eth6-eth9, and that eth6 is the first function on
the port):

 # mkdir /config/eth6
 # mkdir /config/eth7
 # mkdir /config/eth8
 # mkdir /config/eth9

 # echo 50 > /config/eth6/min_bw
 # echo 100 > /config/eth6/max_bw
 # echo 20 > /config/eth7/min_bw
 # echo 100 > /config/eth7/max_bw
 # echo 20 > /config/eth8/min_bw
 # echo 100 > /config/eth8/max_bw
 # echo 10 > /config/eth9/min_bw
 # echo 25 > /config/eth9/max_bw

 # echo 1 > /config/eth6/commit


Data Center Bridging (DCB)
--------------------------
DCB is a configuration Quality of Service implementation in hardware.
It uses the VLAN priority tag (802.1p) to filter traffic. That means
that there are 8 different priorities that traffic can be filtered into.
It also enables priority flow control (802.1Qbb) which can limit or
eliminate the number of dropped packets during network stress. Bandwidth
can be allocated to each of these priorities, which is enforced at the
hardware level (802.1Qaz).

Adapter firmware implements LLDP and DCBX protocol agents as per 802.1AB
and 802.1Qaz respectively. The firmware based DCBX agent runs in willing
mode only and can accept settings from a DCBX capable peer. Software
configuration of DCBX parameters via dcbtool/lldptool are not supported.

The i40e driver implements the DCB netlink interface layer to allow
user-space to communicate with the driver and query DCB configuration for
the port.


Interrupt Rate Limiting
-----------------------

The Intel(R) Ethernet Controller XL710 family supports an interrupt rate
limiting mechanism. The user can control, via ethtool, the number of
microseconds between interrupts.

Syntax:
# ethtool -C ethX rx-usecs-high N

Valid Range: 0-235 (0=no limit)

The range of 0-235 microseconds provides an effective range of 4,310 to
250,000 interrupts per second. The value of rx-usecs-high can be set
independently of rx-usecs and tx-usecs in the same ethtool command, and
is also independent of the adaptive interrupt moderation algorithm. The
underlying hardware supports granularity in 4-microsecond intervals, so
adjacent values may result in the same interrupt rate.

One possible use case is the following:
# ethtool -C ethX adaptive-rx off adaptive-tx off rx-usecs-high 20 rx-usecs 5
tx-usecs 5

The above command would disable adaptive interrupt moderation, and allow a
maximum of 5 microseconds before indicating a receive or transmit was complete.
 However, instead of resulting in as many as 200,000 interrupts per second, it
limits total interrupts per second to 50,000 via the rx-usecs-high parameter.


Performance Optimization:
-------------------------

Driver defaults are meant to fit a wide variety of workloads, but if further
optimization is required we recommend experimenting with the following
settings.

Pin the adapter's IRQs to specific cores by disabling the irqbalance service
and using the included set_irq_affinity script. Please see the script's help
text for further options.

  - The following settings will distribute the IRQs across all the cores
    evenly:

    # scripts/set_irq_affinity -x all <interface1> , [ <interface2>, ... ]

  - The following settings will distribute the IRQs across all the cores that
    are local to the adapter (same NUMA node):

    # scripts/set_irq_affinity -x local <interface1> ,[ <interface2>, ... ]

For very CPU intensive workloads, we recommend pinning the IRQs to all cores.

For IP Forwarding: Disable Adaptive ITR and lower rx and tx interrupts per
queue using ethtool.

  - Setting rx-usecs and tx-usecs to 125 will limit interrupts to about 8000
    interrupts per second per queue.

    # ethtool -C <interface> adaptive-rx off adaptive-tx off rx-usecs 125 
    tx-usecs 125

For lower CPU utilization: Disable Adaptive ITR and lower rx and tx interrupts
per queue using ethtool.

  - Setting rx-usecs and tx-usecs to 250 will limit interrupts to about 4000
    interrupts per second per queue.

    # ethtool -C <interface> adaptive-rx off adaptive-tx off rx-usecs 250 
    tx-usecs 250

For lower latency: Disable Adaptive ITR and ITR by setting rx and tx to 0
using ethtool.

    # ethtool -C <interface> adaptive-rx off adaptive-tx off rx-usecs 0 
    tx-usecs 0


================================================================================


Known Issues/Troubleshooting
----------------------------


Fixing Performance Issues When Using IOMMU in Virtualized Environments
----------------------------------------------------------------------
The IOMMU feature of the processor prevents I/O devices from accessing memory
outside the boundaries set by the OS. It also allows devices to be directly
assigned to a Virtual Machine. However, IOMMU may affect performance, both
in latency (each DMA access by the device must be translated by the IOMMU)
and in CPU utilization (each buffer assigned to every device must be mapped
in the IOMMU).

If you experience significant performance issues with IOMMU, try using it in
“passthrough” mode by adding the following to the kernel boot command line:
  intel_iommu=on iommu=pt

NOTE: This mode enables remapping for assigning devices to VMs, providing
near-native I/O performance, but does not provide the additional memory
protection.


Transmit hangs leading to no traffic
------------------------------------

Disabling flow control while the device is under stress may cause tx hangs and
eventually lead to the device no longer passing traffic. You must reboot the
system to resolve this issue.


Incomplete messages in the system log
-------------------------------------

The NVMUpdate utility may write several incomplete messages in the system log.
These messages take the form:
  in the driver Pci Ex config function byte index 114
  in the driver Pci Ex config function byte index 115
These messages can be ignored.


Bad checksum counter incorrectly increments when using VxLAN
------------------------------------------------------------

When passing non-UDP traffic over a VxLAN interface, the port.rx_csum_bad
counter increments for the packets.


Statistic counters reset when promiscuous mode is changed
---------------------------------------------------------

Changing promiscuous mode triggers a reset of the physical function driver.
This will reset the statistic counters.


Virtual machine does not get link
---------------------------------

If the virtual machine has more than one virtual port assigned to it, and those
virtual ports are bound to different physical ports, you may not get link on all
of the virtual ports. The following command may work around the issue:
ethtool -r <PF>
Where <PF> is the PF interface in the host, for example: p5p1. You may need to
run the command more than once to get link on all virtual ports.


MAC address of Virtual Function changes unexpectedly
----------------------------------------------------

If a Virtual Function's MAC address is not assigned in the host, then the
VF (virtual function) driver will use a random MAC address. This random MAC
address may change each time the VF driver is reloaded. You can assign a
static MAC address in the host machine. This static MAC address will survive
a VF driver reload.


Enabling TSO may cause data integrity issues
--------------------------------------------

Enabling TSO on kernel 3.14 or newer may cause data integrity issues.
Kernel 3.10 and older do not exhibit this behavior.


Changing the number of Rx or Tx queues with ethtool -L may cause a kernel panic
-------------------------------------------------------------------------------

Changing the number of Rx or Tx queues with ethtool -L while traffic is flowing
and the interface is up may cause a kernel panic. Bring the interface down first
to avoid the issue. For example:
  ip link set ethx down
  ethtool -L ethx combined 4


Adding a Flow Director Sideband rule fails incorrectly
------------------------------------------------------

If you try to add a Flow Director rule when no more sideband rule space is
available, i40e logs an error that the rule could not be added, but ethtool
returns success. You can remove rules to free up space. In addition, remove
the rule that failed. This will evict it from the driver's cache.


Flow Director Sideband Logic adds duplicate filter
--------------------------------------------------

The Flow Director Sideband Logic adds a duplicate filter in the software filter
list if the location is not specified or the specified location differs from
the previous location but has the same filter criteria. In this case, the
second of the two filters that appear is the valid one in hardware and it
decides the filter action.


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 following line to the file /etc/sysctl.conf:
net.ipv4.conf.all.arp_filter = 1

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


UDP Stress Test Dropped Packet Issue
------------------------------------

Under small packet UDP stress with the i40edriver, the system may
drop UDP packets due to socket buffers being full. Setting the driver Flow
Control variables to the minimum may resolve the issue. You may also try
increasing the kernel's default buffer sizes by changing the values in

  /proc/sys/net/core/rmem_default and rmem_max


Unplugging Network Cable While ethtool -p is Running
----------------------------------------------------

In kernel versions 2.6.32 and newer, 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.


Rx Page Allocation Errors
-------------------------

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



Disable GRO when routing/bridging
---------------------------------

Due to a known kernel issue, GRO must be turned off when routing/bridging. GRO
can be turned off via ethtool.
ethtool -K ethX gro off

where ethX is the ethernet interface being modified.


Lower than expected performance
-------------------------------

Some PCIe x8 slots are actually configured as x4 slots. These slots have
insufficient bandwidth for full line rate with dual port and quad port
devices. In addition, if you put a PCIe Generation 3-capable adapter
into a PCIe Generation 2 slot, you cannot get full bandwidth. The driver
detects this situation and writes the following message in the system log:

"PCI-Express bandwidth available for this card is not sufficient for optimal
performance. For optimal performance a x8 PCI-Express slot is required."

If this error occurs, moving your adapter to a true PCIe Generation 3 x8 slot
 will resolve the issue.


ethtool may incorrectly display SFP+ fiber module as direct attached cable
--------------------------------------------------------------------------

Due to kernel limitations, port type can only be correctly displayed on kernel
2.6.33 or greater.


Running ethtool -t ethX command causes break between PF and test client
-----------------------------------------------------------------------

When there are active VFs, "ethtool -t" performs a full diagnostic. In the
process, it resets itself and all attached VFs. The VF drivers encouter a
disruption, but are able to recover.


Enabling SR-IOV in a 64-bit Microsoft* Windows Server* 2012/R2 guest OS
under Linux 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 XL710-based controllers.


Unable to obtain DHCP lease on boot with RedHat
-----------------------------------------------

For configurations where the auto-negotiation process takes more than 5
seconds, the boot script may fail with the following message:
"ethX: failed. No link present. Check cable?"

If this error appears even though the presence of a link can be confirmed
using ethtool ethX, try setting "LINKDELAY=5" in
/etc/sysconfig/network-scripts/ifcfg-ethX.

NOTE: Link time can take up to 30 seconds. Adjust LINKDELAY value accordingly.

Alternatively, NetworkManager can be used to configure the interfaces, which
avoids the set timeout. For configuration instructions of NetworkManager
refer to the documentation provided by your distribution.


Loading i40e driver in 3.2.x and newer kernels displays kernel tainted message
------------------------------------------------------------------------------

Due to recent kernel changes, loading an out of tree driver causes the kernel
to be tainted.


================================================================================


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 a supported
kernel with a supported adapter, email the specific information related to the
issue to [email protected].


================================================================================


License
-------

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".

Intel(R) XL710/X710 Network Driver
Intel(R) XL710/X710 Virtual Function Network Driver
Copyright(c) 2014-2015 Intel Corporation.
================================================================================



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.