1.. SPDX-License-Identifier: BSD-3-Clause 2 Copyright(c) 2010-2015 Intel Corporation. 3 Copyright 2017 Mellanox Technologies, Ltd 4 All rights reserved. 5 6.. _linux_gsg_linux_drivers: 7 8Linux Drivers 9============= 10 11Different PMDs may require different kernel drivers in order to work properly. 12Depends on the PMD being used, a corresponding kernel driver should be load 13and bind to the network ports. 14 15UIO 16--- 17 18A small kernel module to set up the device, map device memory to user-space and register interrupts. 19In many cases, the standard ``uio_pci_generic`` module included in the Linux kernel 20can provide the uio capability. This module can be loaded using the command: 21 22.. code-block:: console 23 24 sudo modprobe uio_pci_generic 25 26.. note:: 27 28 ``uio_pci_generic`` module doesn't support the creation of virtual functions. 29 30As an alternative to the ``uio_pci_generic``, the DPDK also includes the igb_uio 31module which can be found in the kernel/linux subdirectory referred to above. It can 32be loaded as shown below: 33 34.. code-block:: console 35 36 sudo modprobe uio 37 sudo insmod <build_dir>/kernel/linux/igb_uio/igb_uio.ko 38 39.. note:: 40 41 Building DPDK Linux kernel modules is disabled by default starting from DPDK 20.02. 42 To enable them again, the config option "enable_kmods" needs to be set 43 in the meson build configuration. 44 See :ref:`adjusting_build_options` for details on how to set/clear build options. 45 It is planned to move ``igb_uio`` module to a different git repository. 46 47.. note:: 48 49 For some devices which lack support for legacy interrupts, e.g. virtual function 50 (VF) devices, the ``igb_uio`` module may be needed in place of ``uio_pci_generic``. 51 52.. note:: 53 54 If UEFI secure boot is enabled, the Linux kernel may disallow the use of 55 UIO on the system. Therefore, devices for use by DPDK should be bound to the 56 ``vfio-pci`` kernel module rather than ``igb_uio`` or ``uio_pci_generic``. 57 For more details see :ref:`linux_gsg_binding_kernel` below. 58 59.. note:: 60 61 If the devices used for DPDK are bound to the ``uio_pci_generic`` kernel module, 62 please make sure that the IOMMU is disabled or passthrough. One can add 63 ``intel_iommu=off`` or ``amd_iommu=off`` or ``intel_iommu=on iommu=pt`` in GRUB 64 command line on x86_64 systems, or add ``iommu.passthrough=1`` on aarch64 system. 65 66Since DPDK release 1.7 onward provides VFIO support, use of UIO is optional 67for platforms that support using VFIO. 68 69VFIO 70---- 71 72A more robust and secure driver in compare to the ``UIO``, relying on IOMMU protection. 73To make use of VFIO, the ``vfio-pci`` module must be loaded: 74 75.. code-block:: console 76 77 sudo modprobe vfio-pci 78 79Note that in order to use VFIO, your kernel must support it. 80VFIO kernel modules have been included in the Linux kernel since version 3.6.0 and are usually present by default, 81however please consult your distributions documentation to make sure that is the case. 82 83The ``vfio-pci`` module since Linux version 5.7 supports the creation of virtual 84functions. After the PF is bound to vfio-pci module, the user can create the VFs 85by sysfs interface, and these VFs are bound to vfio-pci module automatically. 86 87When the PF is bound to vfio-pci, it has initial VF token generated by random. For 88security reason, this token is write only, the user can't read it from the kernel 89directly. To access the VF, the user needs to start the PF with token parameter to 90setup a VF token in UUID format, then the VF can be accessed with this new token. 91 92Since the ``vfio-pci`` module uses the VF token as internal data to provide the 93collaboration between SR-IOV PF and VFs, so DPDK can use the same VF token for all 94PF devices which bound to one application. This VF token can be specified by the EAL 95parameter ``--vfio-vf-token``. 96 97.. code-block:: console 98 99 1. Generate the VF token by uuid command 100 14d63f20-8445-11ea-8900-1f9ce7d5650d 101 102 2. sudo modprobe vfio-pci enable_sriov=1 103 104 2. ./usertools/dpdk-devbind.py -b vfio-pci 0000:86:00.0 105 106 3. echo 2 > /sys/bus/pci/devices/0000:86:00.0/sriov_numvfs 107 108 4. Start the PF: 109 <build_dir>/app/dpdk-testpmd -l 22-25 -n 4 -w 86:00.0 \ 110 --vfio-vf-token=14d63f20-8445-11ea-8900-1f9ce7d5650d --file-prefix=pf -- -i 111 112 5. Start the VF: 113 <build_dir>/app/dpdk-testpmd -l 26-29 -n 4 -w 86:02.0 \ 114 --vfio-vf-token=14d63f20-8445-11ea-8900-1f9ce7d5650d --file-prefix=vf0 -- -i 115 116Also, to use VFIO, both kernel and BIOS must support and be configured to use IO virtualization (such as Intel® VT-d). 117 118.. note:: 119 120 ``vfio-pci`` module doesn't support the creation of virtual functions before Linux version 5.7. 121 122For proper operation of VFIO when running DPDK applications as a non-privileged user, correct permissions should also be set up. 123This can be done by using the DPDK setup script (called dpdk-setup.sh and located in the usertools directory). 124 125.. note:: 126 127 VFIO can be used without IOMMU. While this is just as unsafe as using UIO, it does make it possible for the user to keep the degree of device access and programming that VFIO has, in situations where IOMMU is not available. 128 129.. _bifurcated_driver: 130 131Bifurcated Driver 132----------------- 133 134PMDs which use the bifurcated driver co-exists with the device kernel driver. 135On such model the NIC is controlled by the kernel, while the data 136path is performed by the PMD directly on top of the device. 137 138Such model has the following benefits: 139 140 - It is secure and robust, as the memory management and isolation 141 is done by the kernel. 142 - It enables the user to use legacy linux tools such as ``ethtool`` or 143 ``ifconfig`` while running DPDK application on the same network ports. 144 - It enables the DPDK application to filter only part of the traffic, 145 while the rest will be directed and handled by the kernel driver. 146 The flow bifurcation is performed by the NIC hardware. 147 As an example, using :ref:`flow_isolated_mode` allows to choose 148 strictly what is received in DPDK. 149 150More about the bifurcated driver can be found in 151`Mellanox Bifurcated DPDK PMD 152<https://www.dpdk.org/wp-content/uploads/sites/35/2016/10/Day02-Session04-RonyEfraim-Userspace2016.pdf>`__. 153 154.. _linux_gsg_binding_kernel: 155 156Binding and Unbinding Network Ports to/from the Kernel Modules 157-------------------------------------------------------------- 158 159.. note:: 160 161 PMDs Which use the bifurcated driver should not be unbind from their kernel drivers. this section is for PMDs which use the UIO or VFIO drivers. 162 163As of release 1.4, DPDK applications no longer automatically unbind all supported network ports from the kernel driver in use. 164Instead, in case the PMD being used use the UIO or VFIO drivers, all ports that are to be used by an DPDK application must be bound to the 165``uio_pci_generic``, ``igb_uio`` or ``vfio-pci`` module before the application is run. 166For such PMDs, any network ports under Linux* control will be ignored and cannot be used by the application. 167 168To bind ports to the ``uio_pci_generic``, ``igb_uio`` or ``vfio-pci`` module for DPDK use, 169and then subsequently return ports to Linux* control, 170a utility script called dpdk-devbind.py is provided in the usertools subdirectory. 171This utility can be used to provide a view of the current state of the network ports on the system, 172and to bind and unbind those ports from the different kernel modules, including the uio and vfio modules. 173The following are some examples of how the script can be used. 174A full description of the script and its parameters can be obtained by calling the script with the ``--help`` or ``--usage`` options. 175Note that the uio or vfio kernel modules to be used, should be loaded into the kernel before 176running the ``dpdk-devbind.py`` script. 177 178.. warning:: 179 180 Due to the way VFIO works, there are certain limitations to which devices can be used with VFIO. 181 Mainly it comes down to how IOMMU groups work. 182 Any Virtual Function device can be used with VFIO on its own, but physical devices will require either all ports bound to VFIO, 183 or some of them bound to VFIO while others not being bound to anything at all. 184 185 If your device is behind a PCI-to-PCI bridge, the bridge will then be part of the IOMMU group in which your device is in. 186 Therefore, the bridge driver should also be unbound from the bridge PCI device for VFIO to work with devices behind the bridge. 187 188.. warning:: 189 190 While any user can run the dpdk-devbind.py script to view the status of the network ports, 191 binding or unbinding network ports requires root privileges. 192 193To see the status of all network ports on the system: 194 195.. code-block:: console 196 197 ./usertools/dpdk-devbind.py --status 198 199 Network devices using DPDK-compatible driver 200 ============================================ 201 0000:82:00.0 '82599EB 10-GbE NIC' drv=uio_pci_generic unused=ixgbe 202 0000:82:00.1 '82599EB 10-GbE NIC' drv=uio_pci_generic unused=ixgbe 203 204 Network devices using kernel driver 205 =================================== 206 0000:04:00.0 'I350 1-GbE NIC' if=em0 drv=igb unused=uio_pci_generic *Active* 207 0000:04:00.1 'I350 1-GbE NIC' if=eth1 drv=igb unused=uio_pci_generic 208 0000:04:00.2 'I350 1-GbE NIC' if=eth2 drv=igb unused=uio_pci_generic 209 0000:04:00.3 'I350 1-GbE NIC' if=eth3 drv=igb unused=uio_pci_generic 210 211 Other network devices 212 ===================== 213 <none> 214 215To bind device ``eth1``,``04:00.1``, to the ``uio_pci_generic`` driver: 216 217.. code-block:: console 218 219 ./usertools/dpdk-devbind.py --bind=uio_pci_generic 04:00.1 220 221or, alternatively, 222 223.. code-block:: console 224 225 ./usertools/dpdk-devbind.py --bind=uio_pci_generic eth1 226 227To restore device ``82:00.0`` to its original kernel binding: 228 229.. code-block:: console 230 231 ./usertools/dpdk-devbind.py --bind=ixgbe 82:00.0 232