Commit 04eac393 authored by Donald Hunter's avatar Donald Hunter Committed by Jakub Kicinski
Browse files

docs: netlink: document the sub-type attribute property 



Add a definition for sub-type to the protocol spec doc and a description of
its usage for C arrays in genetlink-legacy.

Signed-off-by: default avatarDonald Hunter <donald.hunter@gmail.com>
Reviewed-by: default avatarBagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 88e28896

Documentation/userspace-api/netlink/genetlink-legacy.rst

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@@ -234,6 +234,20 @@ specify a sub-type. 
          type: binary

          struct: vport-stats



C Arrays

--------



Legacy families also use ``binary`` attributes to encapsulate C arrays. The

``sub-type`` is used to identify the type of scalar to extract.



.. code-block:: yaml



  attributes:

    -

      name: ports

      type: binary

      sub-type: u32



Multi-message DO

----------------

Documentation/userspace-api/netlink/specs.rst

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@@ -254,6 +254,16 @@ rather than depend on what is specified in the spec file. 
The validation policy in the kernel is formed by combining the type

definition (``type`` and ``nested-attributes``) and the ``checks``.



sub-type

~~~~~~~~



Legacy families have special ways of expressing arrays. ``sub-type`` can be

used to define the type of array members in case array members are not

fully defined as attributes (in a bona fide attribute space). For instance

a C array of u32 values can be specified with ``type: binary`` and

``sub-type: u32``. Binary types and legacy array formats are described in

more detail in :doc:`genetlink-legacy`.



operations

----------