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 kmod subdirectory referred to above. It can 32be loaded as shown below: 33 34.. code-block:: console 35 36 sudo modprobe uio 37 sudo insmod kmod/igb_uio.ko 38 39.. note:: 40 41 For some devices which lack support for legacy interrupts, e.g. virtual function 42 (VF) devices, the ``igb_uio`` module may be needed in place of ``uio_pci_generic``. 43 44.. note:: 45 46 If UEFI secure boot is enabled, the Linux kernel may disallow the use of 47 UIO on the system. Therefore, devices for use by DPDK should be bound to the 48 ``vfio-pci`` kernel module rather than ``igb_uio`` or ``uio_pci_generic``. 49 For more details see :ref:`linux_gsg_binding_kernel` below. 50 51.. note:: 52 53 If the devices used for DPDK are bound to the ``uio_pci_generic`` kernel module, 54 please make sure that the IOMMU is disabled or passthrough. One can add 55 ``intel_iommu=off`` or ``amd_iommu=off`` or ``intel_iommu=on iommu=pt``in GRUB 56 command line on x86_64 systems, or add ``iommu.passthrough=1`` on arm64 system. 57 58Since DPDK release 1.7 onward provides VFIO support, use of UIO is optional 59for platforms that support using VFIO. 60 61VFIO 62---- 63 64A more robust and secure driver in compare to the ``UIO``, relying on IOMMU protection. 65To make use of VFIO, the ``vfio-pci`` module must be loaded: 66 67.. code-block:: console 68 69 sudo modprobe vfio-pci 70 71Note that in order to use VFIO, your kernel must support it. 72VFIO kernel modules have been included in the Linux kernel since version 3.6.0 and are usually present by default, 73however please consult your distributions documentation to make sure that is the case. 74 75Also, to use VFIO, both kernel and BIOS must support and be configured to use IO virtualization (such as Intel® VT-d). 76 77.. note:: 78 79 ``vfio-pci`` module doesn't support the creation of virtual functions. 80 81For proper operation of VFIO when running DPDK applications as a non-privileged user, correct permissions should also be set up. 82This can be done by using the DPDK setup script (called dpdk-setup.sh and located in the usertools directory). 83 84.. note:: 85 86 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. 87 88Bifurcated Driver 89----------------- 90 91PMDs which use the bifurcated driver co-exists with the device kernel driver. 92On such model the NIC is controlled by the kernel, while the data 93path is performed by the PMD directly on top of the device. 94 95Such model has the following benefits: 96 97 - It is secure and robust, as the memory management and isolation 98 is done by the kernel. 99 - It enables the user to use legacy linux tools such as ``ethtool`` or 100 ``ifconfig`` while running DPDK application on the same network ports. 101 - It enables the DPDK application to filter only part of the traffic, 102 While the rest will be directed and handled by the kernel driver. 103 104More about the bifurcated driver can be found in 105`Mellanox Bifurcated DPDK PMD 106<https://dpdksummit.com/Archive/pdf/2016Userspace/Day02-Session04-RonyEfraim-Userspace2016.pdf>`__. 107 108.. _linux_gsg_binding_kernel: 109 110Binding and Unbinding Network Ports to/from the Kernel Modules 111-------------------------------------------------------------- 112 113.. note:: 114 115 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. 116 117As of release 1.4, DPDK applications no longer automatically unbind all supported network ports from the kernel driver in use. 118Instead, 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 119``uio_pci_generic``, ``igb_uio`` or ``vfio-pci`` module before the application is run. 120For such PMDs, any network ports under Linux* control will be ignored and cannot be used by the application. 121 122To bind ports to the ``uio_pci_generic``, ``igb_uio`` or ``vfio-pci`` module for DPDK use, 123and then subsequently return ports to Linux* control, 124a utility script called dpdk-devbind.py is provided in the usertools subdirectory. 125This utility can be used to provide a view of the current state of the network ports on the system, 126and to bind and unbind those ports from the different kernel modules, including the uio and vfio modules. 127The following are some examples of how the script can be used. 128A full description of the script and its parameters can be obtained by calling the script with the ``--help`` or ``--usage`` options. 129Note that the uio or vfio kernel modules to be used, should be loaded into the kernel before 130running the ``dpdk-devbind.py`` script. 131 132.. warning:: 133 134 Due to the way VFIO works, there are certain limitations to which devices can be used with VFIO. 135 Mainly it comes down to how IOMMU groups work. 136 Any Virtual Function device can be used with VFIO on its own, but physical devices will require either all ports bound to VFIO, 137 or some of them bound to VFIO while others not being bound to anything at all. 138 139 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. 140 Therefore, the bridge driver should also be unbound from the bridge PCI device for VFIO to work with devices behind the bridge. 141 142.. warning:: 143 144 While any user can run the dpdk-devbind.py script to view the status of the network ports, 145 binding or unbinding network ports requires root privileges. 146 147To see the status of all network ports on the system: 148 149.. code-block:: console 150 151 ./usertools/dpdk-devbind.py --status 152 153 Network devices using DPDK-compatible driver 154 ============================================ 155 0000:82:00.0 '82599EB 10-GbE NIC' drv=uio_pci_generic unused=ixgbe 156 0000:82:00.1 '82599EB 10-GbE NIC' drv=uio_pci_generic unused=ixgbe 157 158 Network devices using kernel driver 159 =================================== 160 0000:04:00.0 'I350 1-GbE NIC' if=em0 drv=igb unused=uio_pci_generic *Active* 161 0000:04:00.1 'I350 1-GbE NIC' if=eth1 drv=igb unused=uio_pci_generic 162 0000:04:00.2 'I350 1-GbE NIC' if=eth2 drv=igb unused=uio_pci_generic 163 0000:04:00.3 'I350 1-GbE NIC' if=eth3 drv=igb unused=uio_pci_generic 164 165 Other network devices 166 ===================== 167 <none> 168 169To bind device ``eth1``,``04:00.1``, to the ``uio_pci_generic`` driver: 170 171.. code-block:: console 172 173 ./usertools/dpdk-devbind.py --bind=uio_pci_generic 04:00.1 174 175or, alternatively, 176 177.. code-block:: console 178 179 ./usertools/dpdk-devbind.py --bind=uio_pci_generic eth1 180 181To restore device ``82:00.0`` to its original kernel binding: 182 183.. code-block:: console 184 185 ./usertools/dpdk-devbind.py --bind=ixgbe 82:00.0 186