Daniel Zahka 2a367002ed devlink: support default values for param-get and param-set
Support querying and resetting to default param values.

Introduce two new devlink netlink attrs:
DEVLINK_ATTR_PARAM_VALUE_DEFAULT and
DEVLINK_ATTR_PARAM_RESET_DEFAULT. The former is used to contain an
optional parameter value inside of the param_value nested
attribute. The latter is used in param-set requests from userspace to
indicate that the driver should reset the param to its default value.

To implement this, two new functions are added to the devlink driver
api: devlink_param::get_default() and
devlink_param::reset_default(). These callbacks allow drivers to
implement default param actions for runtime and permanent cmodes. For
driverinit params, the core latches the last value set by a driver via
devl_param_driverinit_value_set(), and uses that as the default value
for a param.

Because default parameter values are optional, it would be impossible
to discern whether or not a param of type bool has default value of
false or not provided if the default value is encoded using a netlink
flag type. For this reason, when a DEVLINK_PARAM_TYPE_BOOL has an
associated default value, the default value is encoded using a u8
type.

Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
Link: https://patch.msgid.link/20251119025038.651131-4-daniel.zahka@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-20 19:01:22 -08:00
2025-11-15 10:52:01 -08:00
…
2025-02-19 14:53:27 -07:00
2025-11-16 14:25:38 -08:00
…

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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