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.. _devlink_flash:
=============Devlink Flash=============
The ``devlink-flash`` API allows updating device firmware. It replaces theolder ``ethtool-flash`` mechanism, and doesn't require taking anynetworking locks in the kernel to perform the flash update. Example use::
$ devlink dev flash pci/0000:05:00.0 file flash-boot.bin
Note that the file name is a path relative to the firmware loading path(usually ``/lib/firmware/``). Drivers may send status updates to informuser space about the progress of the update operation.
Overwrite Mask==============
The ``devlink-flash`` command allows optionally specifying a mask indicatinghow the device should handle subsections of flash components when updating.This mask indicates the set of sections which are allowed to be overwritten.
.. list-table:: List of overwrite mask bits :widths: 5 95
* - Name - Description * - ``DEVLINK_FLASH_OVERWRITE_SETTINGS`` - Indicates that the device should overwrite settings in the components being updated with the settings found in the provided image. * - ``DEVLINK_FLASH_OVERWRITE_IDENTIFIERS`` - Indicates that the device should overwrite identifiers in the components being updated with the identifiers found in the provided image. This includes MAC addresses, serial IDs, and similar device identifiers.
Multiple overwrite bits may be combined and requested together. If no bitsare provided, it is expected that the device only update firmware binariesin the components being updated. Settings and identifiers are expected to bepreserved across the update. A device may not support every combination andthe driver for such a device must reject any combination which cannot befaithfully implemented.
Firmware Loading================
Devices which require firmware to operate usually store it in non-volatilememory on the board, e.g. flash. Some devices store only basic firmware onthe board, and the driver loads the rest from disk during probing.``devlink-info`` allows users to query firmware information (loadedcomponents and versions).
In other cases the device can both store the image on the board, load fromdisk, or automatically flash a new image from disk. The ``fw_load_policy``devlink parameter can be used to control this behavior(:ref:`Documentation/networking/devlink/devlink-params.rst <devlink_params_generic>`).
On-disk firmware files are usually stored in ``/lib/firmware/``.
Firmware Version Management===========================
Drivers are expected to implement ``devlink-flash`` and ``devlink-info``functionality, which together allow for implementing vendor-independentautomated firmware update facilities.
``devlink-info`` exposes the ``driver`` name and three version groups(``fixed``, ``running``, ``stored``).
The ``driver`` attribute and ``fixed`` group identify the specific devicedesign, e.g. for looking up applicable firmware updates. This is why``serial_number`` is not part of the ``fixed`` versions (even though itis fixed) - ``fixed`` versions should identify the design, not a singledevice.
``running`` and ``stored`` firmware versions identify the firmware runningon the device, and firmware which will be activated after reboot or devicereset.
The firmware update agent is supposed to be able to follow this simplealgorithm to update firmware contents, regardless of the device vendor:
.. code-block:: sh
# Get unique HW design identifier $hw_id = devlink-dev-info['fixed']
# Find out which FW flash we want to use for this NIC $want_flash_vers = some-db-backed.lookup($hw_id, 'flash')
# Update flash if necessary if $want_flash_vers != devlink-dev-info['stored']: $file = some-db-backed.download($hw_id, 'flash') devlink-dev-flash($file)
# Find out the expected overall firmware versions $want_fw_vers = some-db-backed.lookup($hw_id, 'all')
# Update on-disk file if necessary if $want_fw_vers != devlink-dev-info['running']: $file = some-db-backed.download($hw_id, 'disk') write($file, '/lib/firmware/')
# Try device reset, if available if $want_fw_vers != devlink-dev-info['running']: devlink-reset()
# Reboot, if reset wasn't enough if $want_fw_vers != devlink-dev-info['running']: reboot()
Note that each reference to ``devlink-dev-info`` in this pseudo-codeis expected to fetch up-to-date information from the kernel.
For the convenience of identifying firmware files some vendors add``bundle_id`` information to the firmware versions. This meta-version coversmultiple per-component versions and can be used e.g. in firmware file names(all component versions could get rather long.)