1 .. SPDX-License-Identifier: BSD-3-Clause
2 Copyright 2019 Mellanox Technologies, Ltd
4 .. include:: <isonum.txt>
9 The MLX5 vDPA (vhost data path acceleration) driver library
10 (**librte_pmd_mlx5_vdpa**) provides support for **Mellanox ConnectX-6**,
11 **Mellanox ConnectX-6 Dx** and **Mellanox BlueField** families of
12 10/25/40/50/100/200 Gb/s adapters as well as their virtual functions (VF) in
17 Due to external dependencies, this driver is disabled in default
18 configuration of the "make" build. It can be enabled with
19 ``CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD=y`` or by using "meson" build system which
20 will detect dependencies.
26 For security reasons and robustness, this driver only deals with virtual
27 memory addresses. The way resources allocations are handled by the kernel,
28 combined with hardware specifications that allow to handle virtual memory
29 addresses directly, ensure that DPDK applications cannot access random
30 physical memory (or memory that does not belong to the current process).
32 The PMD can use libibverbs and libmlx5 to access the device firmware
33 or directly the hardware components.
34 There are different levels of objects and bypassing abilities
35 to get the best performances:
37 - Verbs is a complete high-level generic API
38 - Direct Verbs is a device-specific API
39 - DevX allows to access firmware objects
40 - Direct Rules manages flow steering at low-level hardware layer
42 Enabling librte_pmd_mlx5_vdpa causes DPDK applications to be linked against
45 A Mellanox mlx5 PCI device can be probed by either net/mlx5 driver or vdpa/mlx5
46 driver but not in parallel. Hence, the user should decide the driver by the
47 ``class`` parameter in the device argument list.
48 By default, the mlx5 device will be probed by the net/mlx5 driver.
53 * Mellanox\ |reg| ConnectX\ |reg|-6 200G MCX654106A-HCAT (2x200G)
54 * Mellanox\ |reg| ConnectX\ |reg|-6 Dx EN 25G MCX621102AN-ADAT (2x25G)
55 * Mellanox\ |reg| ConnectX\ |reg|-6 Dx EN 100G MCX623106AN-CDAT (2x100G)
56 * Mellanox\ |reg| ConnectX\ |reg|-6 Dx EN 200G MCX623105AN-VDAT (1x200G)
57 * Mellanox\ |reg| BlueField SmartNIC 25G MBF1M332A-ASCAT (2x25G)
62 - Mellanox OFED version: **5.0**
63 see :doc:`../../nics/mlx5` guide for more Mellanox OFED details.
68 These options can be modified in the ``.config`` file.
70 - ``CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD`` (default **n**)
72 Toggle compilation of librte_pmd_mlx5 itself.
74 - ``CONFIG_RTE_IBVERBS_LINK_DLOPEN`` (default **n**)
76 Build PMD with additional code to make it loadable without hard
77 dependencies on **libibverbs** nor **libmlx5**, which may not be installed
80 In this mode, their presence is still required for it to run properly,
81 however their absence won't prevent a DPDK application from starting (with
82 ``CONFIG_RTE_BUILD_SHARED_LIB`` disabled) and they won't show up as
83 missing with ``ldd(1)``.
85 It works by moving these dependencies to a purpose-built rdma-core "glue"
86 plug-in which must either be installed in a directory whose name is based
87 on ``CONFIG_RTE_EAL_PMD_PATH`` suffixed with ``-glue`` if set, or in a
88 standard location for the dynamic linker (e.g. ``/lib``) if left to the
89 default empty string (``""``).
91 This option has no performance impact.
93 - ``CONFIG_RTE_IBVERBS_LINK_STATIC`` (default **n**)
95 Embed static flavor of the dependencies **libibverbs** and **libmlx5**
96 in the PMD shared library or the executable static binary.
100 For BlueField, target should be set to ``arm64-bluefield-linux-gcc``. This
101 will enable ``CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD`` and set
102 ``RTE_CACHE_LINE_SIZE`` to 64. Default armv8a configuration of make build and
103 meson build set it to 128 then brings performance degradation.
105 Run-time configuration
106 ~~~~~~~~~~~~~~~~~~~~~~
108 - **ethtool** operations on related kernel interfaces also affect the PMD.
113 - ``class`` parameter [string]
115 Select the class of the driver that should probe the device.
116 `vdpa` for the mlx5 vDPA driver.
118 - ``event_mode`` parameter [int]
120 - 0, Completion queue scheduling will be managed by a timer thread which
121 automatically adjusts its delays to the coming traffic rate.
123 - 1, Completion queue scheduling will be managed by a timer thread with fixed
126 - 2, Completion queue scheduling will be managed by interrupts. Each CQ burst
127 arms the CQ in order to get an interrupt event in the next traffic burst.
131 - ``event_us`` parameter [int]
133 Per mode micro-seconds parameter - relevant only for event mode 0 and 1:
135 - 0, A nonzero value to set timer step in micro-seconds. The timer thread
136 dynamic delay change steps according to this value. Default value is 1us.
138 - 1, A nonzero value to set fixed timer delay in micro-seconds. Default value
141 - ``no_traffic_time`` parameter [int]
143 A nonzero value defines the traffic off time, in seconds, that moves the
144 driver to no-traffic mode. In this mode the timer events are stopped and
145 interrupts are configured to the device in order to notify traffic for the
146 driver. Default value is 2s.