9. I40E Poll Mode Driver

The I40E PMD (librte_pmd_i40e) provides poll mode driver support for the Intel X710/XL710/X722 10/40 Gbps family of adapters.

9.1. Features

Features of the I40E PMD are:

Multiple queues for TX and RX
Receiver Side Scaling (RSS)
MAC/VLAN filtering
Packet type information
Flow director
Cloud filter
Checksum offload
VLAN/QinQ stripping and inserting
TSO offload
Promiscuous mode
Multicast mode
Port hardware statistics
Jumbo frames
Link state information
Link flow control
Mirror on port, VLAN and VSI
Interrupt mode for RX
Scattered and gather for TX and RX
Vector Poll mode driver
DCB
VMDQ
SR-IOV VF
Hot plug
IEEE1588/802.1AS timestamping

9.2. Prerequisites

Identifying your adapter using Intel Support and get the latest NVM/FW images.
Follow the DPDK Getting Started Guide for Linux to setup the basic DPDK environment.
To get better performance on Intel platforms, please follow the “How to get best performance with NICs on Intel platforms” section of the Getting Started Guide for Linux.

9.3. Pre-Installation Configuration

9.3.1. Config File Options

The following options can be modified in the config file. Please note that enabling debugging options may affect system performance.

CONFIG_RTE_LIBRTE_I40E_PMD (default y)

Toggle compilation of the librte_pmd_i40e driver.
CONFIG_RTE_LIBRTE_I40E_DEBUG_* (default n)

Toggle display of generic debugging messages.
CONFIG_RTE_LIBRTE_I40E_RX_ALLOW_BULK_ALLOC (default y)

Toggle bulk allocation for RX.
CONFIG_RTE_LIBRTE_I40E_INC_VECTOR (default n)

Toggle the use of Vector PMD instead of normal RX/TX path. To enable vPMD for RX, bulk allocation for Rx must be allowed.
CONFIG_RTE_LIBRTE_I40E_RX_OLFLAGS_ENABLE (default y)

Toggle to enable RX olflags. This is only meaningful when Vector PMD is used.
CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC (default n)

Toggle to use a 16-byte RX descriptor, by default the RX descriptor is 32 byte.
CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_PF (default 64)

Number of queues reserved for PF.
CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_VF (default 4)

Number of queues reserved for each SR-IOV VF.
CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_VM (default 4)

Number of queues reserved for each VMDQ Pool.
CONFIG_RTE_LIBRTE_I40E_ITR_INTERVAL (default -1)

Interrupt Throttling interval.

9.3.2. Runtime Config Options

Support multiple driver (default disable)

There was a multiple driver support issue during use of 700 series Ethernet Adapter with both Linux kernel and DPDK PMD. To fix this issue, devargs parameter support-multi-driver is introduced, for example:
```
-w 84:00.0,support-multi-driver=1
```
With the above configuration, DPDK PMD will not change global registers, and will switch PF interrupt from IntN to Int0 to avoid interrupt conflict between DPDK and Linux Kernel.

9.3.3. Driver Compilation

To compile the I40E PMD see Getting Started Guide for Linux or Getting Started Guide for FreeBSD depending on your platform.

9.4. Linux

9.4.1. Running testpmd

This section demonstrates how to launch testpmd with Intel XL710/X710 devices managed by librte_pmd_i40e in the Linux operating system.

Load igb_uio or vfio-pci driver:

modprobe uio
insmod ./x86_64-native-linuxapp-gcc/kmod/igb_uio.ko

or

modprobe vfio-pci

Bind the XL710/X710 adapters to igb_uio or vfio-pci loaded in the previous step:
```
./tools/dpdk-devbind.py --bind igb_uio 0000:83:00.0
```
Or setup VFIO permissions for regular users and then bind to vfio-pci:
```
./tools/dpdk-devbind.py --bind vfio-pci 0000:83:00.0
```

Start testpmd with basic parameters:

./x86_64-native-linuxapp-gcc/app/testpmd -c 0xf -n 4 -w 83:00.0 -- -i

Example output:

...
EAL: PCI device 0000:83:00.0 on NUMA socket 1
EAL: probe driver: 8086:1572 rte_i40e_pmd
EAL: PCI memory mapped at 0x7f7f80000000
EAL: PCI memory mapped at 0x7f7f80800000
PMD: eth_i40e_dev_init(): FW 5.0 API 1.5 NVM 05.00.02 eetrack 8000208a
Interactive-mode selected
Configuring Port 0 (socket 0)
...

PMD: i40e_dev_rx_queue_setup(): Rx Burst Bulk Alloc Preconditions are
satisfied.Rx Burst Bulk Alloc function will be used on port=0, queue=0.

...
Port 0: 68:05:CA:26:85:84
Checking link statuses...
Port 0 Link Up - speed 10000 Mbps - full-duplex
Done

testpmd>

9.4.2. SR-IOV: Prerequisites and sample Application Notes

Load the kernel module:

modprobe i40e

Check the output in dmesg:

i40e 0000:83:00.1 ens802f0: renamed from eth0

Bring up the PF ports:
```
ifconfig ens802f0 up
```
Create VF device(s):

Echo the number of VFs to be created into the sriov_numvfs sysfs entry of the parent PF.

Example:
```
echo 2 > /sys/devices/pci0000:00/0000:00:03.0/0000:81:00.0/sriov_numvfs
```

Assign VF MAC address:

Assign MAC address to the VF using iproute2 utility. The syntax is:

ip link set <PF netdev id> vf <VF id> mac <macaddr>

Example:

ip link set ens802f0 vf 0 mac a0:b0:c0:d0:e0:f0

Assign VF to VM, and bring up the VM. Please see the documentation for the I40E/IXGBE/IGB Virtual Function Driver.

9.5. Sample Application Notes

9.5.1. Vlan filter

Vlan filter only works when Promiscuous mode is off.

To start testpmd, and add vlan 10 to port 0:

./app/testpmd -c ffff -n 4 -- -i --forward-mode=mac
...

testpmd> set promisc 0 off
testpmd> rx_vlan add 10 0

9.5.2. Flow Director

The Flow Director works in receive mode to identify specific flows or sets of flows and route them to specific queues. The Flow Director filters can match the different fields for different type of packet: flow type, specific input set per flow type and the flexible payload.

The default input set of each flow type is:

ipv4-other : src_ip_address, dst_ip_address
ipv4-frag  : src_ip_address, dst_ip_address
ipv4-tcp   : src_ip_address, dst_ip_address, src_port, dst_port
ipv4-udp   : src_ip_address, dst_ip_address, src_port, dst_port
ipv4-sctp  : src_ip_address, dst_ip_address, src_port, dst_port,
             verification_tag
ipv6-other : src_ip_address, dst_ip_address
ipv6-frag  : src_ip_address, dst_ip_address
ipv6-tcp   : src_ip_address, dst_ip_address, src_port, dst_port
ipv6-udp   : src_ip_address, dst_ip_address, src_port, dst_port
ipv6-sctp  : src_ip_address, dst_ip_address, src_port, dst_port,
             verification_tag
l2_payload : ether_type

The flex payload is selected from offset 0 to 15 of packet’s payload by default, while it is masked out from matching.

Start testpmd with --disable-rss and --pkt-filter-mode=perfect:

./app/testpmd -c ffff -n 4 -- -i --disable-rss --pkt-filter-mode=perfect \
              --rxq=8 --txq=8 --nb-cores=8 --nb-ports=1

Add a rule to direct ipv4-udp packet whose dst_ip=2.2.2.5, src_ip=2.2.2.3, src_port=32, dst_port=32 to queue 1:

testpmd> flow_director_filter 0 mode IP add flow ipv4-udp  \
         src 2.2.2.3 32 dst 2.2.2.5 32 vlan 0 flexbytes () \
         fwd pf queue 1 fd_id 1

Check the flow director status:

testpmd> show port fdir 0

######################## FDIR infos for port 0      ####################
  MODE:   PERFECT
  SUPPORTED FLOW TYPE:  ipv4-frag ipv4-tcp ipv4-udp ipv4-sctp ipv4-other
                        ipv6-frag ipv6-tcp ipv6-udp ipv6-sctp ipv6-other
                        l2_payload
  FLEX PAYLOAD INFO:
  max_len:       16          payload_limit: 480
  payload_unit:  2           payload_seg:   3
  bitmask_unit:  2           bitmask_num:   2
  MASK:
    vlan_tci: 0x0000,
    src_ipv4: 0x00000000,
    dst_ipv4: 0x00000000,
    src_port: 0x0000,
    dst_port: 0x0000
    src_ipv6: 0x00000000,0x00000000,0x00000000,0x00000000,
    dst_ipv6: 0x00000000,0x00000000,0x00000000,0x00000000
  FLEX PAYLOAD SRC OFFSET:
    L2_PAYLOAD:    0      1      2      3      4      5      6  ...
    L3_PAYLOAD:    0      1      2      3      4      5      6  ...
    L4_PAYLOAD:    0      1      2      3      4      5      6  ...
  FLEX MASK CFG:
    ipv4-udp:    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv4-tcp:    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv4-sctp:   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv4-other:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv4-frag:   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv6-udp:    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv6-tcp:    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv6-sctp:   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv6-other:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    ipv6-frag:   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    l2_payload:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  guarant_count: 1           best_count:    0
  guarant_space: 512         best_space:    7168
  collision:     0           free:          0
  maxhash:       0           maxlen:        0
  add:           0           remove:        0
  f_add:         0           f_remove:      0

Delete all flow director rules on a port:

testpmd> flush_flow_director 0

9.5.3. Floating VEB

The Intel® Ethernet Controller X710 and XL710 Family support a feature called “Floating VEB”.

A Virtual Ethernet Bridge (VEB) is an IEEE Edge Virtual Bridging (EVB) term for functionality that allows local switching between virtual endpoints within a physical endpoint and also with an external bridge/network.

A “Floating” VEB doesn’t have an uplink connection to the outside world so all switching is done internally and remains within the host. As such, this feature provides security benefits.

In addition, a Floating VEB overcomes a limitation of normal VEBs where they cannot forward packets when the physical link is down. Floating VEBs don’t need to connect to the NIC port so they can still forward traffic from VF to VF even when the physical link is down.

Therefore, with this feature enabled VFs can be limited to communicating with each other but not an outside network, and they can do so even when there is no physical uplink on the associated NIC port.

To enable this feature, the user should pass a devargs parameter to the EAL, for example:

-w 84:00.0,enable_floating_veb=1

In this configuration the PMD will use the floating VEB feature for all the VFs created by this PF device.

Alternatively, the user can specify which VFs need to connect to this floating VEB using the floating_veb_list argument:

-w 84:00.0,enable_floating_veb=1,floating_veb_list=1;3-4

In this example VF1, VF3 and VF4 connect to the floating VEB, while other VFs connect to the normal VEB.

The current implementation only supports one floating VEB and one regular VEB. VFs can connect to a floating VEB or a regular VEB according to the configuration passed on the EAL command line.

The floating VEB functionality requires a NIC firmware version of 5.0 or greater.

9.6. Limitations or Known issues

9.6.1. MPLS packet classification on X710/XL710

For firmware versions prior to 5.0, MPLS packets are not recognized by the NIC. The L2 Payload flow type in flow director can be used to classify MPLS packet by using a command in testpmd like:

testpmd> flow_director_filter 0 mode IP add flow l2_payload ether

0x8847 flexbytes () fwd pf queue <N> fd_id <M>

With the NIC firmware version 5.0 or greater, some limited MPLS support is added: Native MPLS (MPLS in Ethernet) skip is implemented, while no new packet type, no classification or offload are possible. With this change, L2 Payload flow type in flow director cannot be used to classify MPLS packet as with previous firmware versions. Meanwhile, the Ethertype filter can be used to classify MPLS packet by using a command in testpmd like:

testpmd> ethertype_filter 0 add mac_ignr 00:00:00:00:00:00 ethertype

0x8847 fwd queue <M>

9.6.2. 16 Byte Descriptor cannot be used on DPDK VF

If the Linux i40e kernel driver is used as host driver, while DPDK i40e PMD is used as the VF driver, DPDK cannot choose 16 byte receive descriptor. That is to say, user should keep CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n in config file.

9.6.3. Link down with i40e kernel driver after DPDK application exist

After DPDK application quit, and the device is bound back to Linux i40e kernel driver, the link cannot be up after ifconfig <dev> up. To work around this issue, ethtool -s <dev> autoneg on should be set first and then the link can be brought up through ifconfig <dev> up.

NOTE: requires Linux kernel i40e driver version >= 1.4.X

9.6.4. Receive packets with Ethertype 0x88A8

Due to the FW limitation, PF can receive packets with Ethertype 0x88A8 only when floating VEB is disabled.

9.6.5. Global configuration warning

I40E PMD will set some global registers to enable some function or set some configure. Then when using different ports of the same NIC with Linux kernel and DPDK, the port with Linux kernel will be impacted by the port with DPDK. For example, register I40E_GL_SWT_L2TAGCTRL is used to control L2 tag, i40e PMD uses I40E_GL_SWT_L2TAGCTRL to set vlan TPID. If setting TPID in port A with DPDK, then the configuration will also impact port B in the NIC with kernel driver, which don’t want to use the TPID. So PMD reports warning to clarify what is changed by writing global register.