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30 MLX4 poll mode driver library
31 =============================
33 The MLX4 poll mode driver library (**librte_pmd_mlx4**) implements support
34 for **Mellanox ConnectX-3** 10/40 Gbps adapters (EN 40, EN 10, Pro EN 40) as
35 well as their virtual functions (VF) in SR-IOV context.
39 Due to external dependencies, this driver is disabled by default. It must
40 be enabled manually by setting ``CONFIG_RTE_LIBRTE_MLX4_PMD=y`` and
43 Implementation details
44 ----------------------
46 Most Mellanox ConnectX-3 devices provide two ports but expose a single PCI
47 bus address, thus unlike most drivers, librte_pmd_mlx4 registers itself as a
48 PCI driver that allocates one Ethernet device per detected port.
50 For this reason, one cannot white/blacklist a single port without also
51 white/blacklisting the others on the same device.
53 Besides its dependency on libibverbs (that implies libmlx4 and associated
54 kernel support), librte_pmd_mlx4 relies heavily on system calls for control
55 operations such as querying/updating the MTU and flow control parameters.
57 For security reasons and robustness, this driver only deals with virtual
58 memory addresses. The way resources allocations are handled by the kernel
59 combined with hardware specifications that allow it to handle virtual memory
60 addresses directly ensure that DPDK applications cannot access random
61 physical memory (or memory that does not belong to the current process).
63 This capability allows the PMD to coexist with kernel network interfaces
64 which remain functional, although they stop receiving unicast packets as
65 long as they share the same MAC address.
67 Compiling librte_pmd_mlx4 causes DPDK to be linked against libibverbs.
69 Features and limitations
70 ------------------------
72 - RSS, also known as RCA, is supported. In this mode the number of
73 configured RX queues must be a power of two.
74 - VLAN filtering is supported.
75 - Link state information is provided.
76 - Promiscuous mode is supported.
77 - All multicast mode is supported.
78 - Multiple MAC addresses (unicast, multicast) can be configured.
79 - Scattered packets are supported for TX and RX.
83 - RSS hash key cannot be modified.
84 - Hardware counters are not implemented (they are software counters).
85 - Checksum offloads are not supported yet.
93 - ``CONFIG_RTE_LIBRTE_MLX4_PMD`` (default **n**)
95 Toggle compilation of librte_pmd_mlx4 itself.
97 - ``CONFIG_RTE_LIBRTE_MLX4_DEBUG`` (default **n**)
99 Toggle debugging code and stricter compilation flags. Enabling this option
100 adds additional run-time checks and debugging messages at the cost of
103 - ``CONFIG_RTE_LIBRTE_MLX4_SGE_WR_N`` (default **4**)
105 Number of scatter/gather elements (SGEs) per work request (WR). Lowering
106 this number improves performance but also limits the ability to receive
107 scattered packets (packets that do not fit a single mbuf). The default
108 value is a safe tradeoff.
110 - ``CONFIG_RTE_LIBRTE_MLX4_MAX_INLINE`` (default **0**)
112 Amount of data to be inlined during TX operations. Improves latency but
115 - ``CONFIG_RTE_LIBRTE_MLX4_TX_MP_CACHE`` (default **8**)
117 Maximum number of cached memory pools (MPs) per TX queue. Each MP from
118 which buffers are to be transmitted must be associated to memory regions
119 (MRs). This is a slow operation that must be cached.
121 This value is always 1 for RX queues since they use a single MP.
123 - ``CONFIG_RTE_LIBRTE_MLX4_SOFT_COUNTERS`` (default **1**)
125 Toggle software counters. No counters are available if this option is
126 disabled since hardware counters are not supported.
128 - ``CONFIG_RTE_LIBRTE_MLX4_COMPAT_VMWARE`` (default **1**)
130 Toggle VMware compatibility code. It also requires the environment
131 variable ``MLX4_COMPAT_VMWARE`` set to a nonzero value at runtime.
133 Environment variables
134 ~~~~~~~~~~~~~~~~~~~~~
136 - ``MLX4_INLINE_RECV_SIZE``
138 A nonzero value enables inline receive for packets up to that size. May
139 significantly improve performance in some cases but lower it in
140 others. Requires careful testing.
142 - ``MLX4_COMPAT_VMWARE``
144 Only supported when compiled with
145 ``CONFIG_RTE_LIBRTE_MLX4_COMPAT_VMWARE=1``. Adds workarounds to run in
146 VMware systems that do not support the flows API properly.
148 Run-time configuration
149 ~~~~~~~~~~~~~~~~~~~~~~
151 - The only constraint when RSS mode is requested is to make sure the number
152 of RX queues is a power of two. This is a hardware requirement.
154 - librte_pmd_mlx4 brings kernel network interfaces up during initialization
155 because it is affected by their state. Forcing them down prevents packets
158 - **ethtool** operations on related kernel interfaces also affect the PMD.
163 This driver relies on external libraries and kernel drivers for resources
164 allocations and initialization. The following dependencies are not part of
165 DPDK and must be installed separately:
169 User space verbs framework used by librte_pmd_mlx4. This library provides
170 a generic interface between the kernel and low-level user space drivers
173 It allows slow and privileged operations (context initialization, hardware
174 resources allocations) to be managed by the kernel and fast operations to
175 never leave user space.
179 Low-level user space driver library for Mellanox ConnectX-3 devices,
180 it is automatically loaded by libibverbs.
182 This library basically implements send/receive calls to the hardware
185 - **Kernel modules** (mlnx-ofed-kernel)
187 They provide the kernel-side verbs API and low level device drivers that
188 manage actual hardware initialization and resources sharing with user
191 Unlike most other PMDs, these modules must remain loaded and bound to
194 - mlx4_core: hardware driver managing Mellanox ConnectX-3 devices.
195 - mlx4_en: Ethernet device driver that provides kernel network interfaces.
196 - mlx4_ib: InifiniBand device driver.
197 - ib_uverbs: user space driver for verbs (entry point for libibverbs).
199 While these libraries and kernel modules are available on OpenFabrics
200 Aliance's `website <https://www.openfabrics.org/>`_ and provided by package
201 managers on most distributions, this PMD requires Ethernet extensions that
202 may not be supported at the moment (this is a work in progress).
205 <http://www.mellanox.com/page/products_dyn?product_family=26&mtag=linux_sw_drivers>`_
206 includes the necessary support and should be used in the meantime. For DPDK,
207 only libibverbs, libmlx4 and mlnx-ofed-kernel packages are required from
212 Both libraries are BSD and GPL licensed. Linux kernel modules are GPL
218 This section demonstrates how to launch **testpmd** with Mellanox ConnectX-3
219 devices managed by librte_pmd_mlx4.
221 #. Load the kernel modules:
223 .. code-block:: console
225 modprobe -a ib_uverbs mlx4_en mlx4_core mlx4_ib
229 User space I/O kernel modules (uio and igb_uio) are not used and do
230 not have to be loaded.
232 #. Make sure Ethernet interfaces are in working order and linked to kernel
233 verbs. Related sysfs entries should be present:
235 .. code-block:: console
237 ls -d /sys/class/net/*/device/infiniband_verbs/uverbs* | cut -d / -f 5
241 .. code-block:: console
248 #. Optionally, retrieve their PCI bus addresses for whitelisting:
250 .. code-block:: console
253 for intf in eth2 eth3 eth4 eth5;
255 (cd "/sys/class/net/${intf}/device/" && pwd -P);
258 sed -n 's,.*/\(.*\),-w \1,p'
262 .. code-block:: console
271 There are only two distinct PCI bus addresses because the Mellanox
272 ConnectX-3 adapters installed on this system are dual port.
274 #. Request huge pages:
276 .. code-block:: console
278 echo 1024 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages/nr_hugepages
280 #. Start testpmd with basic parameters:
282 .. code-block:: console
284 testpmd -c 0xff00 -n 4 -w 0000:83:00.0 -w 0000:84:00.0 -- --rxq=2 --txq=2 -i
288 .. code-block:: console
291 EAL: PCI device 0000:83:00.0 on NUMA socket 1
292 EAL: probe driver: 15b3:1007 librte_pmd_mlx4
293 PMD: librte_pmd_mlx4: PCI information matches, using device "mlx4_0" (VF: false)
294 PMD: librte_pmd_mlx4: 2 port(s) detected
295 PMD: librte_pmd_mlx4: port 1 MAC address is 00:02:c9:b5:b7:50
296 PMD: librte_pmd_mlx4: port 2 MAC address is 00:02:c9:b5:b7:51
297 EAL: PCI device 0000:84:00.0 on NUMA socket 1
298 EAL: probe driver: 15b3:1007 librte_pmd_mlx4
299 PMD: librte_pmd_mlx4: PCI information matches, using device "mlx4_1" (VF: false)
300 PMD: librte_pmd_mlx4: 2 port(s) detected
301 PMD: librte_pmd_mlx4: port 1 MAC address is 00:02:c9:b5:ba:b0
302 PMD: librte_pmd_mlx4: port 2 MAC address is 00:02:c9:b5:ba:b1
303 Interactive-mode selected
304 Configuring Port 0 (socket 0)
305 PMD: librte_pmd_mlx4: 0x867d60: TX queues number update: 0 -> 2
306 PMD: librte_pmd_mlx4: 0x867d60: RX queues number update: 0 -> 2
307 Port 0: 00:02:C9:B5:B7:50
308 Configuring Port 1 (socket 0)
309 PMD: librte_pmd_mlx4: 0x867da0: TX queues number update: 0 -> 2
310 PMD: librte_pmd_mlx4: 0x867da0: RX queues number update: 0 -> 2
311 Port 1: 00:02:C9:B5:B7:51
312 Configuring Port 2 (socket 0)
313 PMD: librte_pmd_mlx4: 0x867de0: TX queues number update: 0 -> 2
314 PMD: librte_pmd_mlx4: 0x867de0: RX queues number update: 0 -> 2
315 Port 2: 00:02:C9:B5:BA:B0
316 Configuring Port 3 (socket 0)
317 PMD: librte_pmd_mlx4: 0x867e20: TX queues number update: 0 -> 2
318 PMD: librte_pmd_mlx4: 0x867e20: RX queues number update: 0 -> 2
319 Port 3: 00:02:C9:B5:BA:B1
320 Checking link statuses...
321 Port 0 Link Up - speed 10000 Mbps - full-duplex
322 Port 1 Link Up - speed 40000 Mbps - full-duplex
323 Port 2 Link Up - speed 10000 Mbps - full-duplex
324 Port 3 Link Up - speed 40000 Mbps - full-duplex