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* Header split 67 68* RX checksum offload 69 70Other features are supported using optional MACRO configuration. They include: 71 72* HW VLAN strip 73 74* L3/L4 packet type 75 76To enable via ``RX_OLFLAGS`` use ``RTE_LIBRTE_FM10K_RX_OLFLAGS_ENABLE=y``. 77 78To guarantee the constraint, the following capabilities in ``dev_conf.rxmode.offloads`` 79will be checked: 80 81* ``DEV_RX_OFFLOAD_VLAN_EXTEND`` 82 83* ``DEV_RX_OFFLOAD_CHECKSUM`` 84 85* ``DEV_RX_OFFLOAD_HEADER_SPLIT`` 86 87* ``fdir_conf->mode`` 88 89 90RX Burst Size 91^^^^^^^^^^^^^ 92 93As vPMD is focused on high throughput, it processes 4 packets at a time. So it assumes 94that the RX burst should be greater than 4 packets per burst. It returns zero if using 95``nb_pkt`` < 4 in the receive handler. If ``nb_pkt`` is not a multiple of 4, a 96floor alignment will be applied. 97 98 99TX Constraint 100~~~~~~~~~~~~~ 101 102Features not Supported by TX Vector PMD 103^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 104 105TX vPMD only works when offloads is set to 0 106 107This means that it does not support any TX offload. 108 109Limitations 110----------- 111 112 113Switch manager 114~~~~~~~~~~~~~~ 115 116The Intel FM10000 family of NICs integrate a hardware switch and multiple host 117interfaces. The FM10000 PMD driver only manages host interfaces. For the 118switch component another switch driver has to be loaded prior to the 119FM10000 PMD driver. The switch driver can be acquired from Intel support. 120Only Testpoint is validated with DPDK, the latest version that has been 121validated with DPDK is 4.1.6. 122 123Support for Switch Restart 124~~~~~~~~~~~~~~~~~~~~~~~~~~ 125 126For FM10000 multi host based design a DPDK app running in the VM or host needs 127to be aware of the switch's state since it may undergo a quit-restart. When 128the switch goes down the DPDK app will receive a LSC event indicating link 129status down, and the app should stop the worker threads that are polling on 130the Rx/Tx queues. When switch comes up, a LSC event indicating ``LINK_UP`` is 131sent to the app, which can then restart the FM10000 port to resume network 132processing. 133 134CRC stripping 135~~~~~~~~~~~~~ 136 137The FM10000 family of NICs strip the CRC for every packets coming into the 138host interface. So, keeping CRC is not supported. 139 140Maximum packet length 141~~~~~~~~~~~~~~~~~~~~~ 142 143The FM10000 family of NICS support a maximum of a 15K jumbo frame. The value 144is fixed and cannot be changed. So, even when the ``rxmode.max_rx_pkt_len`` 145member of ``struct rte_eth_conf`` is set to a value lower than 15364, frames 146up to 15364 bytes can still reach the host interface. 147 148Statistic Polling Frequency 149~~~~~~~~~~~~~~~~~~~~~~~~~~~ 150 151The FM10000 NICs expose a set of statistics via the PCI BARs. These statistics 152are read from the hardware registers when ``rte_eth_stats_get()`` or 153``rte_eth_xstats_get()`` is called. The packet counting registers are 32 bits 154while the byte counting registers are 48 bits. As a result, the statistics must 155be polled regularly in order to ensure the consistency of the returned reads. 156 157Given the PCIe Gen3 x8, about 50Gbps of traffic can occur. With 64 byte packets 158this gives almost 100 million packets/second, causing 32 bit integer overflow 159after approx 40 seconds. To ensure these overflows are detected and accounted 160for in the statistics, it is necessary to read statistic regularly. It is 161suggested to read stats every 20 seconds, which will ensure the statistics 162are accurate. 163 164 165Interrupt mode 166~~~~~~~~~~~~~~ 167 168The FM10000 family of NICS need one separate interrupt for mailbox. So only 169drivers which support multiple interrupt vectors e.g. vfio-pci can work 170for fm10k interrupt mode. 171