1.. SPDX-License-Identifier: BSD-3-Clause 2 Copyright(c) 2015-2016 Intel Corporation. 3 4FM10K Poll Mode Driver 5====================== 6 7The FM10K poll mode driver library provides support for the Intel FM10000 8(FM10K) family of 40GbE/100GbE adapters. 9 10FTAG Based Forwarding of FM10K 11------------------------------ 12 13FTAG Based Forwarding is a unique feature of FM10K. The FM10K family of NICs 14support the addition of a Fabric Tag (FTAG) to carry special information. 15The FTAG is placed at the beginning of the frame, it contains information 16such as where the packet comes from and goes, and the vlan tag. In FTAG based 17forwarding mode, the switch logic forwards packets according to glort (global 18resource tag) information, rather than the mac and vlan table. Currently this 19feature works only on PF. 20 21To enable this feature, the user should pass a devargs parameter to the eal 22like "-a 84:00.0,enable_ftag=1", and the application should make sure an 23appropriate FTAG is inserted for every frame on TX side. 24 25Vector PMD for FM10K 26-------------------- 27 28Vector PMD (vPMD) uses Intel® SIMD instructions to optimize packet I/O. 29It improves load/store bandwidth efficiency of L1 data cache by using a wider 30SSE/AVX ''register (1)''. 31The wider register gives space to hold multiple packet buffers so as to save 32on the number of instructions when bulk processing packets. 33 34There is no change to the PMD API. The RX/TX handlers are the only two entries for 35vPMD packet I/O. They are transparently registered at runtime RX/TX execution 36if all required conditions are met. 37 38Some constraints apply as pre-conditions for specific optimizations on bulk 39packet transfers. The following sections explain RX and TX constraints in the 40vPMD. 41 42 43RX Constraints 44~~~~~~~~~~~~~~ 45 46 47Prerequisites and Pre-conditions 48^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 49 50For Vector RX it is assumed that the number of descriptor rings will be a power 51of 2. With this pre-condition, the ring pointer can easily scroll back to the 52head after hitting the tail without a conditional check. In addition Vector RX 53can use this assumption to do a bit mask using ``ring_size - 1``. 54 55 56Features not Supported by Vector RX PMD 57^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 58 59Some features are not supported when trying to increase the throughput in 60vPMD. They are: 61 62* IEEE1588 63 64* Flow director 65 66* RX checksum offload 67 68Other features are supported using optional MACRO configuration. They include: 69 70* HW VLAN strip 71 72* L3/L4 packet type 73 74To enable via ``RX_OLFLAGS`` use ``RTE_LIBRTE_FM10K_RX_OLFLAGS_ENABLE=y``. 75 76To guarantee the constraint, the following capabilities in ``dev_conf.rxmode.offloads`` 77will be checked: 78 79* ``RTE_ETH_RX_OFFLOAD_VLAN_EXTEND`` 80 81* ``RTE_ETH_RX_OFFLOAD_CHECKSUM`` 82 83 84RX Burst Size 85^^^^^^^^^^^^^ 86 87As vPMD is focused on high throughput, it processes 4 packets at a time. So it assumes 88that the RX burst should be greater than 4 packets per burst. It returns zero if using 89``nb_pkt`` < 4 in the receive handler. If ``nb_pkt`` is not a multiple of 4, a 90floor alignment will be applied. 91 92 93TX Constraint 94~~~~~~~~~~~~~ 95 96Features not Supported by TX Vector PMD 97^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 98 99TX vPMD only works when offloads is set to 0 100 101This means that it does not support any TX offload. 102 103Limitations 104----------- 105 106 107Switch manager 108~~~~~~~~~~~~~~ 109 110The Intel FM10000 family of NICs integrate a hardware switch and multiple host 111interfaces. The FM10000 PMD only manages host interfaces. For the 112switch component another switch driver has to be loaded prior to the 113FM10000 PMD. The switch driver can be acquired from Intel support. 114Only Testpoint is validated with DPDK, the latest version that has been 115validated with DPDK is 4.1.6. 116 117Support for Switch Restart 118~~~~~~~~~~~~~~~~~~~~~~~~~~ 119 120For FM10000 multi host based design a DPDK app running in the VM or host needs 121to be aware of the switch's state since it may undergo a quit-restart. When 122the switch goes down the DPDK app will receive a LSC event indicating link 123status down, and the app should stop the worker threads that are polling on 124the Rx/Tx queues. When switch comes up, a LSC event indicating ``LINK_UP`` is 125sent to the app, which can then restart the FM10000 port to resume network 126processing. 127 128CRC stripping 129~~~~~~~~~~~~~ 130 131The FM10000 family of NICs strip the CRC for every packets coming into the 132host interface. So, keeping CRC is not supported. 133 134Maximum packet length 135~~~~~~~~~~~~~~~~~~~~~ 136 137The FM10000 family of NICS support a maximum of a 15K jumbo frame. The value 138is fixed and cannot be changed. So, even when the ``rxmode.mtu`` 139member of ``struct rte_eth_conf`` is set to a value lower than 15364, frames 140up to 15364 bytes can still reach the host interface. 141 142Statistic Polling Frequency 143~~~~~~~~~~~~~~~~~~~~~~~~~~~ 144 145The FM10000 NICs expose a set of statistics via the PCI BARs. These statistics 146are read from the hardware registers when ``rte_eth_stats_get()`` or 147``rte_eth_xstats_get()`` is called. The packet counting registers are 32 bits 148while the byte counting registers are 48 bits. As a result, the statistics must 149be polled regularly in order to ensure the consistency of the returned reads. 150 151Given the PCIe Gen3 x8, about 50Gbps of traffic can occur. With 64 byte packets 152this gives almost 100 million packets/second, causing 32 bit integer overflow 153after approx 40 seconds. To ensure these overflows are detected and accounted 154for in the statistics, it is necessary to read statistic regularly. It is 155suggested to read stats every 20 seconds, which will ensure the statistics 156are accurate. 157 158 159Interrupt mode 160~~~~~~~~~~~~~~ 161 162The FM10000 family of NICS need one separate interrupt for mailbox. So only 163drivers which support multiple interrupt vectors e.g. vfio-pci can work 164for fm10k interrupt mode. 165