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+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2015-2016 Intel Corporation.
+
+FM10K Poll Mode Driver
+======================
+
+The FM10K poll mode driver library provides support for the Intel FM10000
+(FM10K) family of 40GbE/100GbE adapters.
+
+FTAG Based Forwarding of FM10K
+------------------------------
+
+FTAG Based Forwarding is a unique feature of FM10K. The FM10K family of NICs
+support the addition of a Fabric Tag (FTAG) to carry special information.
+The FTAG is placed at the beginning of the frame, it contains information
+such as where the packet comes from and goes, and the vlan tag. In FTAG based
+forwarding mode, the switch logic forwards packets according to glort (global
+resource tag) information, rather than the mac and vlan table. Currently this
+feature works only on PF.
+
+To enable this feature, the user should pass a devargs parameter to the eal
+like "-w 84:00.0,enable_ftag=1", and the application should make sure an
+appropriate FTAG is inserted for every frame on TX side.
+
+Vector PMD for FM10K
+--------------------
+
+Vector PMD (vPMD) uses Intel® SIMD instructions to optimize packet I/O.
+It improves load/store bandwidth efficiency of L1 data cache by using a wider
+SSE/AVX ''register (1)''.
+The wider register gives space to hold multiple packet buffers so as to save
+on the number of instructions when bulk processing packets.
+
+There is no change to the PMD API. The RX/TX handlers are the only two entries for
+vPMD packet I/O. They are transparently registered at runtime RX/TX execution
+if all required conditions are met.
+
+1.  To date, only an SSE version of FM10K vPMD is available.
+    To ensure that vPMD is in the binary code, set
+    ``CONFIG_RTE_LIBRTE_FM10K_INC_VECTOR=y`` in the configure file.
+
+Some constraints apply as pre-conditions for specific optimizations on bulk
+packet transfers. The following sections explain RX and TX constraints in the
+vPMD.
+
+
+RX Constraints
+~~~~~~~~~~~~~~
+
+
+Prerequisites and Pre-conditions
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+For Vector RX it is assumed that the number of descriptor rings will be a power
+of 2. With this pre-condition, the ring pointer can easily scroll back to the
+head after hitting the tail without a conditional check. In addition Vector RX
+can use this assumption to do a bit mask using ``ring_size - 1``.
+
+
+Features not Supported by Vector RX PMD
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Some features are not supported when trying to increase the throughput in
+vPMD. They are:
+
+*   IEEE1588
+
+*   Flow director
+
+*   Header split
+
+*   RX checksum offload
+
+Other features are supported using optional MACRO configuration. They include:
+
+*   HW VLAN strip
+
+*   L3/L4 packet type
+
+To enable via ``RX_OLFLAGS`` use ``RTE_LIBRTE_FM10K_RX_OLFLAGS_ENABLE=y``.
+
+To guarantee the constraint, the following capabilities in ``dev_conf.rxmode.offloads``
+will be checked:
+
+*   ``DEV_RX_OFFLOAD_VLAN_EXTEND``
+
+*   ``DEV_RX_OFFLOAD_CHECKSUM``
+
+*   ``DEV_RX_OFFLOAD_HEADER_SPLIT``
+
+*   ``fdir_conf->mode``
+
+
+RX Burst Size
+^^^^^^^^^^^^^
+
+As vPMD is focused on high throughput, it processes 4 packets at a time. So it assumes
+that the RX burst should be greater than 4 packets per burst. It returns zero if using
+``nb_pkt`` < 4 in the receive handler. If ``nb_pkt`` is not a multiple of 4, a
+floor alignment will be applied.
+
+
+TX Constraint
+~~~~~~~~~~~~~
+
+Features not Supported by TX Vector PMD
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+TX vPMD only works when offloads is set to 0
+
+This means that it does not support any TX offload.
+
+Limitations
+-----------
+
+
+Switch manager
+~~~~~~~~~~~~~~
+
+The Intel FM10000 family of NICs integrate a hardware switch and multiple host
+interfaces. The FM10000 PMD driver only manages host interfaces. For the
+switch component another switch driver has to be loaded prior to the
+FM10000 PMD driver. The switch driver can be acquired from Intel support.
+Only Testpoint is validated with DPDK, the latest version that has been
+validated with DPDK is 4.1.6.
+
+Support for Switch Restart
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+For FM10000 multi host based design a DPDK app running in the VM or host needs
+to be aware of the switch's state since it may undergo a quit-restart. When
+the switch goes down the DPDK app will receive a LSC event indicating link
+status down, and the app should stop the worker threads that are polling on
+the Rx/Tx queues. When switch comes up, a LSC event indicating ``LINK_UP`` is
+sent to the app, which can then restart the FM10000 port to resume network
+processing.
+
+CRC stripping
+~~~~~~~~~~~~~
+
+The FM10000 family of NICs strip the CRC for every packets coming into the
+host interface. So, keeping CRC is not supported.
+
+Maximum packet length
+~~~~~~~~~~~~~~~~~~~~~
+
+The FM10000 family of NICS support a maximum of a 15K jumbo frame. The value
+is fixed and cannot be changed. So, even when the ``rxmode.max_rx_pkt_len``
+member of ``struct rte_eth_conf`` is set to a value lower than 15364, frames
+up to 15364 bytes can still reach the host interface.
+
+Statistic Polling Frequency
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The FM10000 NICs expose a set of statistics via the PCI BARs. These statistics
+are read from the hardware registers when ``rte_eth_stats_get()`` or
+``rte_eth_xstats_get()`` is called. The packet counting registers are 32 bits
+while the byte counting registers are 48 bits. As a result, the statistics must
+be polled regularly in order to ensure the consistency of the returned reads.
+
+Given the PCIe Gen3 x8, about 50Gbps of traffic can occur. With 64 byte packets
+this gives almost 100 million packets/second, causing 32 bit integer overflow
+after approx 40 seconds. To ensure these overflows are detected and accounted
+for in the statistics, it is necessary to read statistic regularly. It is
+suggested to read stats every 20 seconds, which will ensure the statistics
+are accurate.
+
+
+Interrupt mode
+~~~~~~~~~~~~~~
+
+The FM10000 family of NICS need one separate interrupt for mailbox. So only
+drivers which support multiple interrupt vectors e.g. vfio-pci can work
+for fm10k interrupt mode.