From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- .../userspace-api/netlink/netlink-raw.rst | 194 +++++++++++++++++++++ 1 file changed, 194 insertions(+) create mode 100644 Documentation/userspace-api/netlink/netlink-raw.rst (limited to 'Documentation/userspace-api/netlink/netlink-raw.rst') diff --git a/Documentation/userspace-api/netlink/netlink-raw.rst b/Documentation/userspace-api/netlink/netlink-raw.rst new file mode 100644 index 000000000..aae296c17 --- /dev/null +++ b/Documentation/userspace-api/netlink/netlink-raw.rst @@ -0,0 +1,194 @@ +.. SPDX-License-Identifier: BSD-3-Clause + +====================================================== +Netlink specification support for raw Netlink families +====================================================== + +This document describes the additional properties required by raw Netlink +families such as ``NETLINK_ROUTE`` which use the ``netlink-raw`` protocol +specification. + +Specification +============= + +The netlink-raw schema extends the :doc:`genetlink-legacy ` +schema with properties that are needed to specify the protocol numbers and +multicast IDs used by raw netlink families. See :ref:`classic_netlink` for more +information. The raw netlink families also make use of type-specific +sub-messages. + +Globals +------- + +protonum +~~~~~~~~ + +The ``protonum`` property is used to specify the protocol number to use when +opening a netlink socket. + +.. code-block:: yaml + + # SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) + + name: rt-addr + protocol: netlink-raw + protonum: 0 # part of the NETLINK_ROUTE protocol + + +Multicast group properties +-------------------------- + +value +~~~~~ + +The ``value`` property is used to specify the group ID to use for multicast +group registration. + +.. code-block:: yaml + + mcast-groups: + list: + - + name: rtnlgrp-ipv4-ifaddr + value: 5 + - + name: rtnlgrp-ipv6-ifaddr + value: 9 + - + name: rtnlgrp-mctp-ifaddr + value: 34 + +Sub-messages +------------ + +Several raw netlink families such as +:ref:`rt-link` and +:ref:`tc` use attribute nesting as an +abstraction to carry module specific information. + +Conceptually it looks as follows:: + + [OUTER NEST OR MESSAGE LEVEL] + [GENERIC ATTR 1] + [GENERIC ATTR 2] + [GENERIC ATTR 3] + [GENERIC ATTR - wrapper] + [MODULE SPECIFIC ATTR 1] + [MODULE SPECIFIC ATTR 2] + +The ``GENERIC ATTRs`` at the outer level are defined in the core (or rt_link or +core TC), while specific drivers, TC classifiers, qdiscs etc. can carry their +own information wrapped in the ``GENERIC ATTR - wrapper``. Even though the +example above shows attributes nesting inside the wrapper, the modules generally +have full freedom to define the format of the nest. In practice the payload of +the wrapper attr has very similar characteristics to a netlink message. It may +contain a fixed header / structure, netlink attributes, or both. Because of +those shared characteristics we refer to the payload of the wrapper attribute as +a sub-message. + +A sub-message attribute uses the value of another attribute as a selector key to +choose the right sub-message format. For example if the following attribute has +already been decoded: + +.. code-block:: json + + { "kind": "gre" } + +and we encounter the following attribute spec: + +.. code-block:: yaml + + - + name: data + type: sub-message + sub-message: linkinfo-data-msg + selector: kind + +Then we look for a sub-message definition called ``linkinfo-data-msg`` and use +the value of the ``kind`` attribute i.e. ``gre`` as the key to choose the +correct format for the sub-message: + +.. code-block:: yaml + + sub-messages: + name: linkinfo-data-msg + formats: + - + value: bridge + attribute-set: linkinfo-bridge-attrs + - + value: gre + attribute-set: linkinfo-gre-attrs + - + value: geneve + attribute-set: linkinfo-geneve-attrs + +This would decode the attribute value as a sub-message with the attribute-set +called ``linkinfo-gre-attrs`` as the attribute space. + +A sub-message can have an optional ``fixed-header`` followed by zero or more +attributes from an ``attribute-set``. For example the following +``tc-options-msg`` sub-message defines message formats that use a mixture of +``fixed-header``, ``attribute-set`` or both together: + +.. code-block:: yaml + + sub-messages: + - + name: tc-options-msg + formats: + - + value: bfifo + fixed-header: tc-fifo-qopt + - + value: cake + attribute-set: tc-cake-attrs + - + value: netem + fixed-header: tc-netem-qopt + attribute-set: tc-netem-attrs + +Note that a selector attribute must appear in a netlink message before any +sub-message attributes that depend on it. + +If an attribute such as ``kind`` is defined at more than one nest level, then a +sub-message selector will be resolved using the value 'closest' to the selector. +For example, if the same attribute name is defined in a nested ``attribute-set`` +alongside a sub-message selector and also in a top level ``attribute-set``, then +the selector will be resolved using the value 'closest' to the selector. If the +value is not present in the message at the same level as defined in the spec +then this is an error. + +Nested struct definitions +------------------------- + +Many raw netlink families such as :ref:`tc` +make use of nested struct definitions. The ``netlink-raw`` schema makes it +possible to embed a struct within a struct definition using the ``struct`` +property. For example, the following struct definition embeds the +``tc-ratespec`` struct definition for both the ``rate`` and the ``peakrate`` +members of ``struct tc-tbf-qopt``. + +.. code-block:: yaml + + - + name: tc-tbf-qopt + type: struct + members: + - + name: rate + type: binary + struct: tc-ratespec + - + name: peakrate + type: binary + struct: tc-ratespec + - + name: limit + type: u32 + - + name: buffer + type: u32 + - + name: mtu + type: u32 -- cgit v1.3.1