Re: [PATCH net-next v8 09/10] netlink: specs: Add ethernet port listing with ethtool

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

On 25/03/2026 09:19, Maxime Chevallier wrote:
> Ethernet network interfaces may have more than one front-facing port.
> The phy_port infrastructure was introduced to keep track of
> these ports, and allow userspace to know about the presence and
> capability of these ports. Add a ethnl netlink message to report this
> information.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
>  Documentation/netlink/specs/ethtool.yaml      | 50 +++++++++++++++++++
>  Documentation/networking/ethtool-netlink.rst  | 35 +++++++++++++
>  .../uapi/linux/ethtool_netlink_generated.h    | 19 +++++++
>  3 files changed, 104 insertions(+)
> 
> diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
> index 5dd4d1b5d94b..9b907f40aba0 100644
> --- a/Documentation/netlink/specs/ethtool.yaml
> +++ b/Documentation/netlink/specs/ethtool.yaml
> @@ -210,6 +210,10 @@ definitions:
>        -
>          name: discard
>          value: 31
> +  -
> +    name: port-type
> +    type: enum
> +    entries: [mdi, sfp]
>  
>  attribute-sets:
>    -
> @@ -1905,6 +1909,32 @@ attribute-sets:
>          name: link
>          type: nest
>          nested-attributes: mse-snapshot
> +  -
> +    name: port
> +    attr-cnt-name: --ethtool-a-port-cnt
> +    attributes:
> +      -
> +        name: header
> +        type: nest
> +        nested-attributes: header
> +      -
> +        name: id
> +        type: u32
> +      -
> +        name: supported-modes
> +        type: nest
> +        nested-attributes: bitset
> +      -
> +        name: supported-interfaces
> +        type: nest
> +        nested-attributes: bitset
> +      -
> +        name: type
> +        type: u32
> +        enum: port-type
> +      -
> +        name: vacant
> +        type: u32
>  
>  operations:
>    enum-model: directional
> @@ -2859,6 +2889,26 @@ operations:
>              - worst-channel
>              - link
>        dump: *mse-get-op
> +    -
> +      name: port-get
> +      doc: Get ports attached to an interface
> +
> +      attribute-set: port
> +
> +      do: &port-get-op
> +        request:
> +          attributes:
> +            - header
> +            - id
> +        reply:
> +          attributes:
> +            - header
> +            - id
> +            - supported-modes
> +            - supported-interfaces
> +            - type
> +            - vacant
> +      dump: *port-get-op
>  
>  mcast-groups:
>    list:
> diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
> index e92abf45faf5..0a5dfba55870 100644
> --- a/Documentation/networking/ethtool-netlink.rst
> +++ b/Documentation/networking/ethtool-netlink.rst
> @@ -2537,6 +2537,40 @@ Within each channel nest, only the metrics supported by the PHY will be present.
>  See ``struct phy_mse_snapshot`` kernel documentation in
>  ``include/linux/phy.h``.
>  
> +PORT_GET
> +========
> +
> +Retrieve information about the physical connection points of a network device,
> +referred to as "ports". User needs to specify a PORT_ID for the DO operation,
> +in which case the DO request returns information about that specific port.
> +
> +As there can be more than one port, the DUMP operation can be used to list the
> +ports present on a given interface, by passing an interface index or name in
> +the dump request.
> +
> +Request contents:
> +
> +  ===================================== ======  ===============================
> +  ``ETHTOOL_A_PORT_HEADER``             nested  request header
> +  ``ETHTOOL_A_PORT_ID``                 u32     port id
> +  ===================================== ======  ===============================
> +
> +Kernel response contents:
> +
> +  ======================================= ======  =============================
> +  ``ETHTOOL_A_PORT_HEADER``               nested  request header
> +  ``ETHTOOL_A_PORT_ID``                   u32     the port's unique identifier,
> +                                                  per netdevice.
> +  ``ETHTOOL_A_PORT_SUPPORTED_MODES``      bitset  bitset of supported linkmodes
> +  ``ETHTOOL_A_PORT_SUPPORTED_INTERFACES`` bitset  bitset of supported MII
> +                                                  interfaces
> +  ``ETHTOOL_A_PORT_TYPE``                 u8      the port type
> +  ``ETHTOOL_A_PORT_VACANT``               u8      for non-mdi ports, indicates
> +                                                  if the port is connected to
> +                                                  another device that could
> +                                                  expose a MDI

ah forgot to update this doc here, should be u32...  :(