doc/netlink: Update genetlink-legacy documentation

Add documentation for recently added genetlink-legacy schema attributes.
Remove statements about 'work in progress' and 'todo'.
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20230825122756.7603-4-donald.hunter@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/core-api/netlink.rst

@@ -67,10 +67,11 @@ Globals
 kernel-policy
 ~~~~~~~~~~~~~
 
-Defines if the kernel validation policy is per operation (``per-op``)
-or for the entire family (``global``). New families should use ``per-op``
-(default) to be able to narrow down the attributes accepted by a specific
-command.
+Defines whether the kernel validation policy is ``global`` i.e. the same for all
+operations of the family, defined for each operation individually - ``per-op``,
+or separately for each operation and operation type (do vs dump) - ``split``.
+New families should use ``per-op`` (default) to be able to narrow down the
+attributes accepted by a specific command.
 
 checks
 ------

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

@@ -8,11 +8,8 @@ This document describes the many additional quirks and properties
 required to describe older Generic Netlink families which form
 the ``genetlink-legacy`` protocol level.
 
-The spec is a work in progress, some of the quirks are just documented
-for future reference.
-
-Specification (defined)
-=======================
+Specification
+=============
 
 Attribute type nests
 --------------------
@@ -156,16 +153,27 @@ it will be allocated 3 for the request (``a`` is the previous operation
 with a request section and the value of 2) and 8 for response (``c`` is
 the previous operation in the "from-kernel" direction).
 
-Other quirks (todo)
-===================
+Other quirks
+============
 
 Structures
 ----------
 
 Legacy families can define C structures both to be used as the contents of
 an attribute and as a fixed message header. Structures are defined in
-``definitions``  and referenced in operations or attributes. Note that
-structures defined in YAML are implicitly packed according to C
+``definitions``  and referenced in operations or attributes.
+
+members
+~~~~~~~
+
+ - ``name`` - The attribute name of the struct member
+ - ``type`` - One of the scalar types ``u8``, ``u16``, ``u32``, ``u64``, ``s8``,
+   ``s16``, ``s32``, ``s64``, ``string`` or ``binary``.
+ - ``byte-order`` - ``big-endian`` or ``little-endian``
+ - ``doc``, ``enum``, ``enum-as-flags``, ``display-hint`` - Same as for
+   :ref:`attribute definitions <attribute_properties>`
+
+Note that structures defined in YAML are implicitly packed according to C
 conventions. For example, the following struct is 4 bytes, not 6 bytes:
 
 .. code-block:: c

Documentation/userspace-api/netlink/specs.rst

@@ -68,6 +68,10 @@ The following sections describe the properties of the most modern ``genetlink``
 schema. See the documentation of :doc:`genetlink-c <c-code-gen>`
 for information on how C names are derived from name properties.
 
+See also :ref:`Documentation/core-api/netlink.rst <kernel_netlink>` for
+information on the Netlink specification properties that are only relevant to
+the kernel space and not part of the user space API.
+
 genetlink
 =========
 
@@ -180,6 +184,8 @@ attributes
 
 List of attributes in the set.
 
+.. _attribute_properties:
+
 Attribute properties
 --------------------
 
@@ -264,6 +270,13 @@ 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`.
 
+display-hint
+~~~~~~~~~~~~
+
+Optional format indicator that is intended only for choosing the right
+formatting mechanism when displaying values of this type. Currently supported
+hints are ``hex``, ``mac``, ``fddi``, ``ipv4``, ``ipv6`` and ``uuid``.
+
 operations
 ----------