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diff --git a/src/spdk/dpdk/doc/guides/vdpadevs/mlx5.rst b/src/spdk/dpdk/doc/guides/vdpadevs/mlx5.rst new file mode 100644 index 000000000..dd377afda --- /dev/null +++ b/src/spdk/dpdk/doc/guides/vdpadevs/mlx5.rst @@ -0,0 +1,113 @@ +.. SPDX-License-Identifier: BSD-3-Clause + Copyright 2019 Mellanox Technologies, Ltd + +.. include:: <isonum.txt> + +MLX5 vDPA driver +================ + +The MLX5 vDPA (vhost data path acceleration) driver library +(**librte_pmd_mlx5_vdpa**) provides support for **Mellanox ConnectX-6**, +**Mellanox ConnectX-6 Dx** and **Mellanox BlueField** families of +10/25/40/50/100/200 Gb/s adapters as well as their virtual functions (VF) in +SR-IOV context. + +.. note:: + + Due to external dependencies, this driver is disabled in default + configuration of the "make" build. It can be enabled with + ``CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD=y`` or by using "meson" build system which + will detect dependencies. + + +Design +------ + +For security reasons and robustness, this driver only deals with virtual +memory addresses. The way resources allocations are handled by the kernel, +combined with hardware specifications that allow to handle virtual memory +addresses directly, ensure that DPDK applications cannot access random +physical memory (or memory that does not belong to the current process). + +The PMD can use libibverbs and libmlx5 to access the device firmware +or directly the hardware components. +There are different levels of objects and bypassing abilities +to get the best performances: + +- Verbs is a complete high-level generic API +- Direct Verbs is a device-specific API +- DevX allows to access firmware objects +- Direct Rules manages flow steering at low-level hardware layer + +Enabling librte_pmd_mlx5_vdpa causes DPDK applications to be linked against +libibverbs. + +A Mellanox mlx5 PCI device can be probed by either net/mlx5 driver or vdpa/mlx5 +driver but not in parallel. Hence, the user should decide the driver by the +``class`` parameter in the device argument list. +By default, the mlx5 device will be probed by the net/mlx5 driver. + +Supported NICs +-------------- + +* Mellanox\ |reg| ConnectX\ |reg|-6 200G MCX654106A-HCAT (2x200G) +* Mellanox\ |reg| ConnectX\ |reg|-6 Dx EN 100G MCX623106AN-CDAT (2x100G) +* Mellanox\ |reg| ConnectX\ |reg|-6 Dx EN 200G MCX623105AN-VDAT (1x200G) +* Mellanox\ |reg| BlueField SmartNIC 25G MBF1M332A-ASCAT (2x25G) + +Prerequisites +------------- + +- Mellanox OFED version: **5.0** + see :doc:`../../nics/mlx5` guide for more Mellanox OFED details. + +Compilation options +~~~~~~~~~~~~~~~~~~~ + +These options can be modified in the ``.config`` file. + +- ``CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD`` (default **n**) + + Toggle compilation of librte_pmd_mlx5 itself. + +- ``CONFIG_RTE_IBVERBS_LINK_DLOPEN`` (default **n**) + + Build PMD with additional code to make it loadable without hard + dependencies on **libibverbs** nor **libmlx5**, which may not be installed + on the target system. + + In this mode, their presence is still required for it to run properly, + however their absence won't prevent a DPDK application from starting (with + ``CONFIG_RTE_BUILD_SHARED_LIB`` disabled) and they won't show up as + missing with ``ldd(1)``. + + It works by moving these dependencies to a purpose-built rdma-core "glue" + plug-in which must either be installed in a directory whose name is based + on ``CONFIG_RTE_EAL_PMD_PATH`` suffixed with ``-glue`` if set, or in a + standard location for the dynamic linker (e.g. ``/lib``) if left to the + default empty string (``""``). + + This option has no performance impact. + +- ``CONFIG_RTE_IBVERBS_LINK_STATIC`` (default **n**) + + Embed static flavor of the dependencies **libibverbs** and **libmlx5** + in the PMD shared library or the executable static binary. + +.. note:: + + For BlueField, target should be set to ``arm64-bluefield-linux-gcc``. This + will enable ``CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD`` and set + ``RTE_CACHE_LINE_SIZE`` to 64. Default armv8a configuration of make build and + meson build set it to 128 then brings performance degradation. + +Run-time configuration +~~~~~~~~~~~~~~~~~~~~~~ + +- **ethtool** operations on related kernel interfaces also affect the PMD. + +- ``class`` parameter [string] + + Select the class of the driver that should probe the device. + `vdpa` for the mlx5 vDPA driver. + |