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feat(linux): Add CPSW RX Network Flow Classification documentation #799

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100 changes: 100 additions & 0 deletions ...linux/Foundational_Components/Kernel/Kernel_Drivers/Network/_K3-CPSW-common.rst
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Expand Up @@ -476,6 +476,106 @@
and writing of EEE advertising settings in Ethernet PHY. This way one
can disable advertising EEE for certain speeds.

.. rubric:: ``ethtool -N|--config-nfc DEVNAME`` Configure RX Network Flow Classification
:name: k3-ethtool-config-nfc

The CPSW driver supports RX classification through the Address Lookup Engine (ALE).

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[vale] reported by reviewdog 🐶
[RedHat.Definitions] Define acronyms and abbreviations (such as 'CPSW') on first occurrence if they're likely to be unfamiliar.

Raw Output:
{"message":"[RedHat.Definitions] Define acronyms and abbreviations (such as 'CPSW') on first occurrence if they're likely to be unfamiliar.","location":{"path":"source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/_K3-CPSW-common.rst","range":{"start":{"line":482,"column":5},"end":{"line":482,"column":9}}},"severity":"INFO","code":{"value":"RedHat.Definitions","url":"https://redhat-documentation.github.io/vale-at-red-hat/reference-guide.html#definitions"}}
This allows for steering of received packets to specific RX channels
or dropping them based on Ethernet header fields. The ``-N`` or ``--config-nfc``
flags of :command:`ethtool` set the receiving network flow classification rules.

Currently only raw Ethernet (flow-type ``ether``) matching is supported with
the following fields:

- Source MAC address (``src``)
- Destination MAC address (``dst``)

The action specifies the target RX channel (0-7) or ``-1`` to drop the packet.

.. note::

RX classification requires multiple RX channels to be configured first using

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[RedHat.PassiveVoice] 'be configured' is passive voice. In general, use active voice. Consult the style guide for acceptable use of passive voice.

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{"message":"[RedHat.PassiveVoice] 'be configured' is passive voice. In general, use active voice. Consult the style guide for acceptable use of passive voice.","location":{"path":"source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/_K3-CPSW-common.rst","range":{"start":{"line":497,"column":55},"end":{"line":497,"column":68}}},"severity":"INFO","code":{"value":"RedHat.PassiveVoice","url":"https://redhat-documentation.github.io/vale-at-red-hat/reference-guide.html#passive-voice"}}

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[RedHat.SimpleWords] Use simple language. Consider using 'many' rather than 'multiple'.

Raw Output:
{"message":"[RedHat.SimpleWords] Use simple language. Consider using 'many' rather than 'multiple'.","location":{"path":"source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/_K3-CPSW-common.rst","range":{"start":{"line":497,"column":31},"end":{"line":497,"column":39}}},"severity":"INFO","code":{"value":"RedHat.SimpleWords","url":"https://redhat-documentation.github.io/vale-at-red-hat/reference-guide.html#simple-words"}}
``ethtool -L <dev> rx <N>`` where N is the number of channels (up to 8).

.. rubric:: **Syntax**

.. code-block:: console

ethtool -N <dev> flow-type ether [src <MAC>] [dst <MAC>] action <channel>

Where:

- ``flow-type ether`` - Raw Ethernet frame matching (only supported type)
- ``src <MAC>`` - Source MAC address (format: xx:yy:zz:aa:bb:cc)
- ``dst <MAC>`` - Destination MAC address (format: xx:yy:zz:aa:bb:cc)
- ``action <channel>`` - Target RX channel (0-7) or -1 for drop

.. rubric:: **Prerequisites**

Increase number of RX channels before adding classification rules:

.. code-block:: console

ip link set eth0 down
ethtool -L eth0 rx 8
ip link set eth0 up

.. rubric:: **Test Cases**

#. **Ether Source Address Test**

Route traffic from specific source MAC to RX channel 5:

.. code-block:: console

ethtool -N eth0 flow-type ether src xx:yy:zz:aa:bb:cc action 5

Traffic from that address should route to channel 5.

#. **Ether Destination Address Test**

Route traffic to specific destination MAC to RX channel 4:

.. code-block:: console

ethtool -N eth0 flow-type ether dst yy:zz:aa:bb:cc:dd action 4

Traffic to that address should route to channel 4.

#. **Drop Test**

Drop traffic from specific source MAC:

.. code-block:: console

ethtool -N eth0 flow-type ether src xx:yy:zz:aa:bb:cc action -1

Traffic from that address should be dropped.

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[RedHat.PassiveVoice] 'be dropped' is passive voice. In general, use active voice. Consult the style guide for acceptable use of passive voice.

Raw Output:
{"message":"[RedHat.PassiveVoice] 'be dropped' is passive voice. In general, use active voice. Consult the style guide for acceptable use of passive voice.","location":{"path":"source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/_K3-CPSW-common.rst","range":{"start":{"line":553,"column":37},"end":{"line":553,"column":47}}},"severity":"INFO","code":{"value":"RedHat.PassiveVoice","url":"https://redhat-documentation.github.io/vale-at-red-hat/reference-guide.html#passive-voice"}}

.. rubric:: **Viewing Configured Rules**

Use ``ethtool -n`` (or ``--show-nfc``) to display active RX classification rules:

.. code-block:: console

# ethtool -n eth0
1 RX flow classifications
[0]: flow-type ether src xx:yy:zz:aa:bb:cc action 5

.. rubric:: **Deleting Rules**

Delete a specific rule by its index (shown in ``ethtool -n`` output):

.. code-block:: console

ethtool -N eth0 delete <index>

Example:

.. code-block:: console

ethtool -N eth0 delete 0

.. rubric:: ``ethtool -d|--register-dump DEVNAME`` Do a register dump
:name: k3-ethtool-do-a-register-dump

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