devlink-flash.rst (4761B)
1.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2 3.. _devlink_flash: 4 5============= 6Devlink Flash 7============= 8 9The ``devlink-flash`` API allows updating device firmware. It replaces the 10older ``ethtool-flash`` mechanism, and doesn't require taking any 11networking locks in the kernel to perform the flash update. Example use:: 12 13 $ devlink dev flash pci/0000:05:00.0 file flash-boot.bin 14 15Note that the file name is a path relative to the firmware loading path 16(usually ``/lib/firmware/``). Drivers may send status updates to inform 17user space about the progress of the update operation. 18 19Overwrite Mask 20============== 21 22The ``devlink-flash`` command allows optionally specifying a mask indicating 23how the device should handle subsections of flash components when updating. 24This mask indicates the set of sections which are allowed to be overwritten. 25 26.. list-table:: List of overwrite mask bits 27 :widths: 5 95 28 29 * - Name 30 - Description 31 * - ``DEVLINK_FLASH_OVERWRITE_SETTINGS`` 32 - Indicates that the device should overwrite settings in the components 33 being updated with the settings found in the provided image. 34 * - ``DEVLINK_FLASH_OVERWRITE_IDENTIFIERS`` 35 - Indicates that the device should overwrite identifiers in the 36 components being updated with the identifiers found in the provided 37 image. This includes MAC addresses, serial IDs, and similar device 38 identifiers. 39 40Multiple overwrite bits may be combined and requested together. If no bits 41are provided, it is expected that the device only update firmware binaries 42in the components being updated. Settings and identifiers are expected to be 43preserved across the update. A device may not support every combination and 44the driver for such a device must reject any combination which cannot be 45faithfully implemented. 46 47Firmware Loading 48================ 49 50Devices which require firmware to operate usually store it in non-volatile 51memory on the board, e.g. flash. Some devices store only basic firmware on 52the board, and the driver loads the rest from disk during probing. 53``devlink-info`` allows users to query firmware information (loaded 54components and versions). 55 56In other cases the device can both store the image on the board, load from 57disk, or automatically flash a new image from disk. The ``fw_load_policy`` 58devlink parameter can be used to control this behavior 59(:ref:`Documentation/networking/devlink/devlink-params.rst <devlink_params_generic>`). 60 61On-disk firmware files are usually stored in ``/lib/firmware/``. 62 63Firmware Version Management 64=========================== 65 66Drivers are expected to implement ``devlink-flash`` and ``devlink-info`` 67functionality, which together allow for implementing vendor-independent 68automated firmware update facilities. 69 70``devlink-info`` exposes the ``driver`` name and three version groups 71(``fixed``, ``running``, ``stored``). 72 73The ``driver`` attribute and ``fixed`` group identify the specific device 74design, e.g. for looking up applicable firmware updates. This is why 75``serial_number`` is not part of the ``fixed`` versions (even though it 76is fixed) - ``fixed`` versions should identify the design, not a single 77device. 78 79``running`` and ``stored`` firmware versions identify the firmware running 80on the device, and firmware which will be activated after reboot or device 81reset. 82 83The firmware update agent is supposed to be able to follow this simple 84algorithm to update firmware contents, regardless of the device vendor: 85 86.. code-block:: sh 87 88 # Get unique HW design identifier 89 $hw_id = devlink-dev-info['fixed'] 90 91 # Find out which FW flash we want to use for this NIC 92 $want_flash_vers = some-db-backed.lookup($hw_id, 'flash') 93 94 # Update flash if necessary 95 if $want_flash_vers != devlink-dev-info['stored']: 96 $file = some-db-backed.download($hw_id, 'flash') 97 devlink-dev-flash($file) 98 99 # Find out the expected overall firmware versions 100 $want_fw_vers = some-db-backed.lookup($hw_id, 'all') 101 102 # Update on-disk file if necessary 103 if $want_fw_vers != devlink-dev-info['running']: 104 $file = some-db-backed.download($hw_id, 'disk') 105 write($file, '/lib/firmware/') 106 107 # Try device reset, if available 108 if $want_fw_vers != devlink-dev-info['running']: 109 devlink-reset() 110 111 # Reboot, if reset wasn't enough 112 if $want_fw_vers != devlink-dev-info['running']: 113 reboot() 114 115Note that each reference to ``devlink-dev-info`` in this pseudo-code 116is expected to fetch up-to-date information from the kernel. 117 118For the convenience of identifying firmware files some vendors add 119``bundle_id`` information to the firmware versions. This meta-version covers 120multiple per-component versions and can be used e.g. in firmware file names 121(all component versions could get rather long.)