code:
=============================
Netlink interface for ethtool
=============================

Basic information
=================

Netlink interface for ethtool uses generic netlink family ``ethtool``
(userspace application should use macros ``ETHTOOL_GENL_NAME`` and
``ETHTOOL_GENL_VERSION`` defined in ``<linux/ethtool_netlink.h>`` uapi
header). This family does not use a specific header, all information in
requests and replies is passed using netlink attributes.

The ethtool netlink interface uses extended ACK for error and warning
reporting, userspace application developers are encouraged to make these
messages available to user in a suitable way.

Requests can be divided into three categories: "get" (retrieving information),
"set" (setting parameters) and "action" (invoking an action).

All "set" and "action" type requests require admin privileges
(``CAP_NET_ADMIN`` in the namespace). Most "get" type requests are allowed for
anyone but there are exceptions (where the response contains sensitive
information). In some cases, the request as such is allowed for anyone but
unprivileged users have attributes with sensitive information (e.g.
wake-on-lan password) omitted.

Conventions
===========

Attributes which represent a boolean value usually use NLA_U8 type so that we
can distinguish three states: "on", "off" and "not present" (meaning the
information is not available in "get" requests or value is not to be changed
in "set" requests). For these attributes, the "true" value should be passed as
number 1 but any non-zero value should be understood as "true" by recipient.
In the tables below, "bool" denotes NLA_U8 attributes interpreted in this way.

In the message structure descriptions below, if an attribute name is suffixed
with "+", parent nest can contain multiple attributes of the same type. This
implements an array of entries.

Attributes that need to be filled-in by device drivers and that are dumped to
user space based on whether they are valid or not should not use zero as a
valid value. This avoids the need to explicitly signal the validity of the
attribute in the device driver API.

Request header
==============

Each request or reply message contains a nested attribute with common header.
Structure of this header is

  ==============================  ======  =============================
  ``ETHTOOL_A_HEADER_DEV_INDEX``  u32     device ifindex
  ``ETHTOOL_A_HEADER_DEV_NAME``   string  device name
  ``ETHTOOL_A_HEADER_FLAGS``      u32     flags common for all requests
  ==============================  ======  =============================

``ETHTOOL_A_HEADER_DEV_INDEX`` and ``ETHTOOL_A_HEADER_DEV_NAME`` identify the
device message relates to. One of them is sufficient in requests, if both are
used, they must identify the same device. Some requests, e.g. global string
sets, do not require device identification. Most ``GET`` requests also allow
dump requests without device identification to query the same information for
all devices providing it (each device in a separate message).

``ETHTOOL_A_HEADER_FLAGS`` is a bitmap of request flags common for all request
types. The interpretation of these flags is the same for all request types but
the flags may not apply to requests. Recognized flags are:

  =================================  ===================================
  ``ETHTOOL_FLAG_COMPACT_BITSETS``   use compact format bitsets in reply
  ``ETHTOOL_FLAG_OMIT_REPLY``        omit optional reply (_SET and _ACT)
  ``ETHTOOL_FLAG_STATS``             include optional device statistics
  =================================  ===================================

New request flags should follow the general idea that if the flag is not set,
the behaviour is backward compatible, i.e. requests from old clients not aware
of the flag should be interpreted the way the client expects. A client must
not set flags it does not understand.

Bit sets
========

For short bitmaps of (reasonably) fixed length, standard ``NLA_BITFIELD32``
type is used. For arbitrary length bitmaps, ethtool netlink uses a nested
attribute with contents of one of two forms: compact (two binary bitmaps
representing bit values and mask of affected bits) and bit-by-bit (list of
bits identified by either index or name).

Verbose (bit-by-bit) bitsets allow sending symbolic names for bits together
with their values which saves a round trip (when the bitset is passed in a
request) or at least a second request (when the bitset is in a reply). This is
useful for one shot applications like traditional ethtool command. On the
other hand, long running applications like ethtool monitor (displaying
notifications) or network management daemons may prefer fetching the names
only once and using compact form to save message size. Notifications from
ethtool netlink interface always use compact form for bitsets.

A bitset can represent either a value/mask pair (``ETHTOOL_A_BITSET_NOMASK``
not set) or a single bitmap (``ETHTOOL_A_BITSET_NOMASK`` set). In requests
modifying a bitmap, the former changes the bit set in mask to values set in
value and preserves the rest; the latter sets the bits set in the bitmap and
clears the rest.

Compact form: nested (bitset) atrribute contents:

  ============================  ======  ============================
  ``ETHTOOL_A_BITSET_NOMASK``   flag    no mask, only a list
  ``ETHTOOL_A_BITSET_SIZE``     u32     number of significant bits
  ``ETHTOOL_A_BITSET_VALUE``    binary  bitmap of bit values
  ``ETHTOOL_A_BITSET_MASK``     binary  bitmap of valid bits
  ============================  ======  ============================

Value and mask must have length at least ``ETHTOOL_A_BITSET_SIZE`` bits
rounded up to a multiple of 32 bits. They consist of 32-bit words in host byte
order, words ordered from least significant to most significant (i.e. the same
way as bitmaps are passed with ioctl interface).

For compact form, ``ETHTOOL_A_BITSET_SIZE`` and ``ETHTOOL_A_BITSET_VALUE`` are
mandatory. ``ETHTOOL_A_BITSET_MASK`` attribute is mandatory if
``ETHTOOL_A_BITSET_NOMASK`` is not set (bitset represents a value/mask pair);
if ``ETHTOOL_A_BITSET_NOMASK`` is not set, ``ETHTOOL_A_BITSET_MASK`` is not
allowed (bitset represents a single bitmap.

Kernel bit set length may differ from userspace length if older application is
used on newer kernel or vice versa. If userspace bitmap is longer, an error is
issued only if the request actually tries to set values of some bits not
recognized by kernel.

Bit-by-bit form: nested (bitset) attribute contents:

 +------------------------------------+--------+-----------------------------+
 | ``ETHTOOL_A_BITSET_NOMASK``        | flag   | no mask, only a list        |
 +------------------------------------+--------+-----------------------------+
 | ``ETHTOOL_A_BITSET_SIZE``          | u32    | number of significant bits  |
 +------------------------------------+--------+-----------------------------+
 | ``ETHTOOL_A_BITSET_BITS``          | nested | array of bits               |
 +-+----------------------------------+--------+-----------------------------+
 | | ``ETHTOOL_A_BITSET_BITS_BIT+``   | nested | one bit                     |
 +-+-+--------------------------------+--------+-----------------------------+
 | | | ``ETHTOOL_A_BITSET_BIT_INDEX`` | u32    | bit index (0 for LSB)       |
 +-+-+--------------------------------+--------+-----------------------------+
 | | | ``ETHTOOL_A_BITSET_BIT_NAME``  | string | bit name                    |
 +-+-+--------------------------------+--------+-----------------------------+
 | | | ``ETHTOOL_A_BITSET_BIT_VALUE`` | flag   | present if bit is set       |
 +-+-+--------------------------------+--------+-----------------------------+

Bit size is optional for bit-by-bit form. ``ETHTOOL_A_BITSET_BITS`` nest can
only contain ``ETHTOOL_A_BITSET_BITS_BIT`` attributes but there can be an
arbitrary number of them.  A bit may be identified by its index or by its
name. When used in requests, listed bits are set to 0 or 1 according to
``ETHTOOL_A_BITSET_BIT_VALUE``, the rest is preserved. A request fails if
index exceeds kernel bit length or if name is not recognized.

When ``ETHTOOL_A_BITSET_NOMASK`` flag is present, bitset is interpreted as
a simple bitmap. ``ETHTOOL_A_BITSET_BIT_VALUE`` attributes are not used in
such case. Such bitset represents a bitmap with listed bits set and the rest
zero.

In requests, application can use either form. Form used by kernel in reply is
determined by ``ETHTOOL_FLAG_COMPACT_BITSETS`` flag in flags field of request
header. Semantics of value and mask depends on the attribute.

List of message types
=====================

All constants identifying message types use ``ETHTOOL_CMD_`` prefix and suffix
according to message purpose:

  ==============    ======================================
  ``_GET``          userspace request to retrieve data
  ``_SET``          userspace request to set data
  ``_ACT``          userspace request to perform an action
  ``_GET_REPLY``    kernel reply to a ``GET`` request
  ``_SET_REPLY``    kernel reply to a ``SET`` request
  ``_ACT_REPLY``    kernel reply to an ``ACT`` request
  ``_NTF``          kernel notification
  ==============    ======================================

Userspace to kernel:

  ===================================== =================================
  ``ETHTOOL_MSG_STRSET_GET``            get string set
  ``ETHTOOL_MSG_LINKINFO_GET``          get link settings
  ``ETHTOOL_MSG_LINKINFO_SET``          set link settings
  ``ETHTOOL_MSG_LINKMODES_GET``         get link modes info
  ``ETHTOOL_MSG_LINKMODES_SET``         set link modes info
  ``ETHTOOL_MSG_LINKSTATE_GET``         get link state
  ``ETHTOOL_MSG_DEBUG_GET``             get debugging settings
  ``ETHTOOL_MSG_DEBUG_SET``             set debugging settings
  ``ETHTOOL_MSG_WOL_GET``               get wake-on-lan settings
  ``ETHTOOL_MSG_WOL_SET``               set wake-on-lan settings
  ``ETHTOOL_MSG_FEATURES_GET``          get device features
  ``ETHTOOL_MSG_FEATURES_SET``          set device features
  ``ETHTOOL_MSG_PRIVFLAGS_GET``         get private flags
  ``ETHTOOL_MSG_PRIVFLAGS_SET``         set private flags
  ``ETHTOOL_MSG_RINGS_GET``             get ring sizes
  ``ETHTOOL_MSG_RINGS_SET``             set ring sizes
  ``ETHTOOL_MSG_CHANNELS_GET``          get channel counts
  ``ETHTOOL_MSG_CHANNELS_SET``          set channel counts
  ``ETHTOOL_MSG_COALESCE_GET``          get coalescing parameters
  ``ETHTOOL_MSG_COALESCE_SET``          set coalescing parameters
  ``ETHTOOL_MSG_PAUSE_GET``             get pause parameters
  ``ETHTOOL_MSG_PAUSE_SET``             set pause parameters
  ``ETHTOOL_MSG_EEE_GET``               get EEE settings
  ``ETHTOOL_MSG_EEE_SET``               set EEE settings
  ``ETHTOOL_MSG_TSINFO_GET``		get timestamping info
  ``ETHTOOL_MSG_CABLE_TEST_ACT``        action start cable test
  ``ETHTOOL_MSG_CABLE_TEST_TDR_ACT``    action start raw TDR cable test
  ``ETHTOOL_MSG_TUNNEL_INFO_GET``       get tunnel offload info
  ``ETHTOOL_MSG_FEC_GET``               get FEC settings
  ``ETHTOOL_MSG_FEC_SET``               set FEC settings
  ``ETHTOOL_MSG_MODULE_EEPROM_GET``     read SFP module EEPROM
  ``ETHTOOL_MSG_STATS_GET``             get standard statistics
  ``ETHTOOL_MSG_PHC_VCLOCKS_GET``       get PHC virtual clocks info
  ``ETHTOOL_MSG_MODULE_SET``            set transceiver module parameters
  ``ETHTOOL_MSG_MODULE_GET``            get transceiver module parameters
  ``ETHTOOL_MSG_PSE_SET``               set PSE parameters
  ``ETHTOOL_MSG_PSE_GET``               get PSE parameters
  ``ETHTOOL_MSG_RSS_GET``               get RSS settings
  ===================================== =================================

Kernel to userspace:

  ======================================== =================================
  ``ETHTOOL_MSG_STRSET_GET_REPLY``         string set contents
  ``ETHTOOL_MSG_LINKINFO_GET_REPLY``       link settings
  ``ETHTOOL_MSG_LINKINFO_NTF``             link settings notification
  ``ETHTOOL_MSG_LINKMODES_GET_REPLY``      link modes info
  ``ETHTOOL_MSG_LINKMODES_NTF``            link modes notification
  ``ETHTOOL_MSG_LINKSTATE_GET_REPLY``      link state info
  ``ETHTOOL_MSG_DEBUG_GET_REPLY``          debugging settings
  ``ETHTOOL_MSG_DEBUG_NTF``                debugging settings notification
  ``ETHTOOL_MSG_WOL_GET_REPLY``            wake-on-lan settings
  ``ETHTOOL_MSG_WOL_NTF``                  wake-on-lan settings notification
  ``ETHTOOL_MSG_FEATURES_GET_REPLY``       device features
  ``ETHTOOL_MSG_FEATURES_SET_REPLY``       optional reply to FEATURES_SET
  ``ETHTOOL_MSG_FEATURES_NTF``             netdev features notification
  ``ETHTOOL_MSG_PRIVFLAGS_GET_REPLY``      private flags
  ``ETHTOOL_MSG_PRIVFLAGS_NTF``            private flags
  ``ETHTOOL_MSG_RINGS_GET_REPLY``          ring sizes
  ``ETHTOOL_MSG_RINGS_NTF``                ring sizes
  ``ETHTOOL_MSG_CHANNELS_GET_REPLY``       channel counts
  ``ETHTOOL_MSG_CHANNELS_NTF``             channel counts
  ``ETHTOOL_MSG_COALESCE_GET_REPLY``       coalescing parameters
  ``ETHTOOL_MSG_COALESCE_NTF``             coalescing parameters
  ``ETHTOOL_MSG_PAUSE_GET_REPLY``          pause parameters
  ``ETHTOOL_MSG_PAUSE_NTF``                pause parameters
  ``ETHTOOL_MSG_EEE_GET_REPLY``            EEE settings
  ``ETHTOOL_MSG_EEE_NTF``                  EEE settings
  ``ETHTOOL_MSG_TSINFO_GET_REPLY``         timestamping info
  ``ETHTOOL_MSG_CABLE_TEST_NTF``           Cable test results
  ``ETHTOOL_MSG_CABLE_TEST_TDR_NTF``       Cable test TDR results
  ``ETHTOOL_MSG_TUNNEL_INFO_GET_REPLY``    tunnel offload info
  ``ETHTOOL_MSG_FEC_GET_REPLY``            FEC settings
  ``ETHTOOL_MSG_FEC_NTF``                  FEC settings
  ``ETHTOOL_MSG_MODULE_EEPROM_GET_REPLY``  read SFP module EEPROM
  ``ETHTOOL_MSG_STATS_GET_REPLY``          standard statistics
  ``ETHTOOL_MSG_PHC_VCLOCKS_GET_REPLY``    PHC virtual clocks info
  ``ETHTOOL_MSG_MODULE_GET_REPLY``         transceiver module parameters
  ``ETHTOOL_MSG_PSE_GET_REPLY``            PSE parameters
  ``ETHTOOL_MSG_RSS_GET_REPLY``            RSS settings
  ======================================== =================================

``GET`` requests are sent by userspace applications to retrieve device
information. They usually do not contain any message specific attributes.
Kernel replies with corresponding "GET_REPLY" message. For most types, ``GET``
request with ``NLM_F_DUMP`` and no device identification can be used to query
the information for all devices supporting the request.

If the data can be also modified, corresponding ``SET`` message with the same
layout as corresponding ``GET_REPLY`` is used to request changes. Only
attributes where a change is requested are included in such request (also, not
all attributes may be changed). Replies to most ``SET`` request consist only
of error code and extack; if kernel provides additional data, it is sent in
the form of corresponding ``SET_REPLY`` message which can be suppressed by
setting ``ETHTOOL_FLAG_OMIT_REPLY`` flag in request header.

Data modification also triggers sending a ``NTF`` message with a notification.
These usually bear only a subset of attributes which was affected by the
change. The same notification is issued if the data is modified using other
means (mostly ioctl ethtool interface). Unlike notifications from ethtool
netlink code which are only sent if something actually changed, notifications
triggered by ioctl interface may be sent even if the request did not actually
change any data.

``ACT`` messages request kernel (driver) to perform a specific action. If some
information is reported by kernel (which can be suppressed by setting
``ETHTOOL_FLAG_OMIT_REPLY`` flag in request header), the reply takes form of
an ``ACT_REPLY`` message. Performing an action also triggers a notification
(``NTF`` message).

Later sections describe the format and semantics of these messages.

STRSET_GET
==========

Requests contents of a string set as provided by ioctl commands
``ETHTOOL_GSSET_INFO`` and ``ETHTOOL_GSTRINGS.`` String sets are not user
writeable so that the corresponding ``STRSET_SET`` message is only used in
kernel replies. There are two types of string sets: global (independent of
a device, e.g. device feature names) and device specific (e.g. device private
flags).

Request contents:

 +---------------------------------------+--------+------------------------+
 | ``ETHTOOL_A_STRSET_HEADER``           | nested | request header         |
 +---------------------------------------+--------+------------------------+
 | ``ETHTOOL_A_STRSET_STRINGSETS``       | nested | string set to request  |
 +-+-------------------------------------+--------+------------------------+
 | | ``ETHTOOL_A_STRINGSETS_STRINGSET+`` | nested | one string set         |
 +-+-+-----------------------------------+--------+------------------------+
 | | | ``ETHTOOL_A_STRINGSET_ID``        | u32    | set id                 |
 +-+-+-----------------------------------+--------+------------------------+

Kernel response contents:

 +---------------------------------------+--------+-----------------------+
 | ``ETHTOOL_A_STRSET_HEADER``           | nested | reply header          |
 +---------------------------------------+--------+-----------------------+
 | ``ETHTOOL_A_STRSET_STRINGSETS``       | nested | array of string sets  |
 +-+-------------------------------------+--------+-----------------------+
 | | ``ETHTOOL_A_STRINGSETS_STRINGSET+`` | nested | one string set        |
 +-+-+-----------------------------------+--------+-----------------------+
 | | | ``ETHTOOL_A_STRINGSET_ID``        | u32    | set id                |
 +-+-+-----------------------------------+--------+-----------------------+
 | | | ``ETHTOOL_A_STRINGSET_COUNT``     | u32    | number of strings     |
 +-+-+-----------------------------------+--------+-----------------------+
 | | | ``ETHTOOL_A_STRINGSET_STRINGS``   | nested | array of strings      |
 +-+-+-+---------------------------------+--------+-----------------------+
 | | | | ``ETHTOOL_A_STRINGS_STRING+``   | nested | one string            |
 +-+-+-+-+-------------------------------+--------+-----------------------+
 | | | | | ``ETHTOOL_A_STRING_INDEX``    | u32    | string index          |
 +-+-+-+-+-------------------------------+--------+-----------------------+
 | | | | | ``ETHTOOL_A_STRING_VALUE``    | string | string value          |
 +-+-+-+-+-------------------------------+--------+-----------------------+
 | ``ETHTOOL_A_STRSET_COUNTS_ONLY``      | flag   | return only counts    |
 +---------------------------------------+--------+-----------------------+

Device identification in request header is optional. Depending on its presence
a and ``NLM_F_DUMP`` flag, there are three type of ``STRSET_GET`` requests:

 - no ``NLM_F_DUMP,`` no device: get "global" stringsets
 - no ``NLM_F_DUMP``, with device: get string sets related to the device
 - ``NLM_F_DUMP``, no device: get device related string sets for all devices

If there is no ``ETHTOOL_A_STRSET_STRINGSETS`` array, all string sets of
requested type are returned, otherwise only those specified in the request.
Flag ``ETHTOOL_A_STRSET_COUNTS_ONLY`` tells kernel to only return string
counts of the sets, not the actual strings.

LINKINFO_GET
============

Requests link settings as provided by ``ETHTOOL_GLINKSETTINGS`` except for
link modes and autonegotiation related information. The request does not use
any attributes.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_LINKINFO_HEADER``         nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_LINKINFO_HEADER``         nested  reply header
  ``ETHTOOL_A_LINKINFO_PORT``           u8      physical port
  ``ETHTOOL_A_LINKINFO_PHYADDR``        u8      phy MDIO address
  ``ETHTOOL_A_LINKINFO_TP_MDIX``        u8      MDI(-X) status
  ``ETHTOOL_A_LINKINFO_TP_MDIX_CTRL``   u8      MDI(-X) control
  ``ETHTOOL_A_LINKINFO_TRANSCEIVER``    u8      transceiver
  ====================================  ======  ==========================

Attributes and their values have the same meaning as matching members of the
corresponding ioctl structures.

``LINKINFO_GET`` allows dump requests (kernel returns reply message for all
devices supporting the request).

LINKINFO_SET
============

``LINKINFO_SET`` request allows setting some of the attributes reported by
``LINKINFO_GET``.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_LINKINFO_HEADER``         nested  request header
  ``ETHTOOL_A_LINKINFO_PORT``           u8      physical port
  ``ETHTOOL_A_LINKINFO_PHYADDR``        u8      phy MDIO address
  ``ETHTOOL_A_LINKINFO_TP_MDIX_CTRL``   u8      MDI(-X) control
  ====================================  ======  ==========================

MDI(-X) status and transceiver cannot be set, request with the corresponding
attributes is rejected.

LINKMODES_GET
=============

Requests link modes (supported, advertised and peer advertised) and related
information (autonegotiation status, link speed and duplex) as provided by
``ETHTOOL_GLINKSETTINGS``. The request does not use any attributes.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_LINKMODES_HEADER``        nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ==========================================  ======  ==========================
  ``ETHTOOL_A_LINKMODES_HEADER``              nested  reply header
  ``ETHTOOL_A_LINKMODES_AUTONEG``             u8      autonegotiation status
  ``ETHTOOL_A_LINKMODES_OURS``                bitset  advertised link modes
  ``ETHTOOL_A_LINKMODES_PEER``                bitset  partner link modes
  ``ETHTOOL_A_LINKMODES_SPEED``               u32     link speed (Mb/s)
  ``ETHTOOL_A_LINKMODES_DUPLEX``              u8      duplex mode
  ``ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG``    u8      Master/slave port mode
  ``ETHTOOL_A_LINKMODES_MASTER_SLAVE_STATE``  u8      Master/slave port state
  ``ETHTOOL_A_LINKMODES_RATE_MATCHING``       u8      PHY rate matching
  ==========================================  ======  ==========================

For ``ETHTOOL_A_LINKMODES_OURS``, value represents advertised modes and mask
represents supported modes. ``ETHTOOL_A_LINKMODES_PEER`` in the reply is a bit
list.

``LINKMODES_GET`` allows dump requests (kernel returns reply messages for all
devices supporting the request).

LINKMODES_SET
=============

Request contents:

  ==========================================  ======  ==========================
  ``ETHTOOL_A_LINKMODES_HEADER``              nested  request header
  ``ETHTOOL_A_LINKMODES_AUTONEG``             u8      autonegotiation status
  ``ETHTOOL_A_LINKMODES_OURS``                bitset  advertised link modes
  ``ETHTOOL_A_LINKMODES_PEER``                bitset  partner link modes
  ``ETHTOOL_A_LINKMODES_SPEED``               u32     link speed (Mb/s)
  ``ETHTOOL_A_LINKMODES_DUPLEX``              u8      duplex mode
  ``ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG``    u8      Master/slave port mode
  ``ETHTOOL_A_LINKMODES_RATE_MATCHING``       u8      PHY rate matching
  ``ETHTOOL_A_LINKMODES_LANES``               u32     lanes
  ==========================================  ======  ==========================

``ETHTOOL_A_LINKMODES_OURS`` bit set allows setting advertised link modes. If
autonegotiation is on (either set now or kept from before), advertised modes
are not changed (no ``ETHTOOL_A_LINKMODES_OURS`` attribute) and at least one
of speed, duplex and lanes is specified, kernel adjusts advertised modes to all
supported modes matching speed, duplex, lanes or all (whatever is specified).
This autoselection is done on ethtool side with ioctl interface, netlink
interface is supposed to allow requesting changes without knowing what exactly
kernel supports.

LINKSTATE_GET
=============

Requests link state information. Link up/down flag (as provided by
``ETHTOOL_GLINK`` ioctl command) is provided. Optionally, extended state might
be provided as well. In general, extended state describes reasons for why a port
is down, or why it operates in some non-obvious mode. This request does not have
any attributes.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_LINKSTATE_HEADER``        nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ============================
  ``ETHTOOL_A_LINKSTATE_HEADER``        nested  reply header
  ``ETHTOOL_A_LINKSTATE_LINK``          bool    link state (up/down)
  ``ETHTOOL_A_LINKSTATE_SQI``           u32     Current Signal Quality Index
  ``ETHTOOL_A_LINKSTATE_SQI_MAX``       u32     Max support SQI value
  ``ETHTOOL_A_LINKSTATE_EXT_STATE``     u8      link extended state
  ``ETHTOOL_A_LINKSTATE_EXT_SUBSTATE``  u8      link extended substate
  ``ETHTOOL_A_LINKSTATE_EXT_DOWN_CNT``  u32     count of link down events
  ====================================  ======  ============================

For most NIC drivers, the value of ``ETHTOOL_A_LINKSTATE_LINK`` returns
carrier flag provided by ``netif_carrier_ok()`` but there are drivers which
define their own handler.

``ETHTOOL_A_LINKSTATE_EXT_STATE`` and ``ETHTOOL_A_LINKSTATE_EXT_SUBSTATE`` are
optional values. ethtool core can provide either both
``ETHTOOL_A_LINKSTATE_EXT_STATE`` and ``ETHTOOL_A_LINKSTATE_EXT_SUBSTATE``,
or only ``ETHTOOL_A_LINKSTATE_EXT_STATE``, or none of them.

``LINKSTATE_GET`` allows dump requests (kernel returns reply messages for all
devices supporting the request).

Link extended states:

  ================================================      ============================================
  ``ETHTOOL_LINK_EXT_STATE_AUTONEG``                    States relating to the autonegotiation or
                                                        issues therein

  ``ETHTOOL_LINK_EXT_STATE_LINK_TRAINING_FAILURE``      Failure during link training

  ``ETHTOOL_LINK_EXT_STATE_LINK_LOGICAL_MISMATCH``      Logical mismatch in physical coding sublayer
                                                        or forward error correction sublayer

  ``ETHTOOL_LINK_EXT_STATE_BAD_SIGNAL_INTEGRITY``       Signal integrity issues

  ``ETHTOOL_LINK_EXT_STATE_NO_CABLE``                   No cable connected

  ``ETHTOOL_LINK_EXT_STATE_CABLE_ISSUE``                Failure is related to cable,
                                                        e.g., unsupported cable

  ``ETHTOOL_LINK_EXT_STATE_EEPROM_ISSUE``               Failure is related to EEPROM, e.g., failure
                                                        during reading or parsing the data

  ``ETHTOOL_LINK_EXT_STATE_CALIBRATION_FAILURE``        Failure during calibration algorithm

  ``ETHTOOL_LINK_EXT_STATE_POWER_BUDGET_EXCEEDED``      The hardware is not able to provide the
                                                        power required from cable or module

  ``ETHTOOL_LINK_EXT_STATE_OVERHEAT``                   The module is overheated

  ``ETHTOOL_LINK_EXT_STATE_MODULE``                     Transceiver module issue
  ================================================      ============================================

Link extended substates:

  Autoneg substates:

  ===============================================================   ================================
  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NO_PARTNER_DETECTED``              Peer side is down

  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_ACK_NOT_RECEIVED``                 Ack not received from peer side

  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NEXT_PAGE_EXCHANGE_FAILED``        Next page exchange failed

  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NO_PARTNER_DETECTED_FORCE_MODE``   Peer side is down during force
                                                                    mode or there is no agreement of
                                                                    speed

  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_FEC_MISMATCH_DURING_OVERRIDE``     Forward error correction modes
                                                                    in both sides are mismatched

  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NO_HCD``                           No Highest Common Denominator
  ===============================================================   ================================

  Link training substates:

  ===========================================================================   ====================
  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_KR_FRAME_LOCK_NOT_ACQUIRED``                    Frames were not
                                                                                recognized, the
                                                                                lock failed

  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_KR_LINK_INHIBIT_TIMEOUT``                       The lock did not
                                                                                occur before
                                                                                timeout

  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_KR_LINK_PARTNER_DID_NOT_SET_RECEIVER_READY``    Peer side did not
                                                                                send ready signal
                                                                                after training
                                                                                process

  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_REMOTE_FAULT``                                  Remote side is not
                                                                                ready yet
  ===========================================================================   ====================

  Link logical mismatch substates:

  ================================================================   ===============================
  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_PCS_DID_NOT_ACQUIRE_BLOCK_LOCK``   Physical coding sublayer was
                                                                     not locked in first phase -
                                                                     block lock

  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_PCS_DID_NOT_ACQUIRE_AM_LOCK``      Physical coding sublayer was
                                                                     not locked in second phase -
                                                                     alignment markers lock

  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_PCS_DID_NOT_GET_ALIGN_STATUS``     Physical coding sublayer did
                                                                     not get align status

  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_FC_FEC_IS_NOT_LOCKED``             FC forward error correction is
                                                                     not locked

  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_RS_FEC_IS_NOT_LOCKED``             RS forward error correction is
                                                                     not locked
  ================================================================   ===============================

  Bad signal integrity substates:

  =================================================================    =============================
  ``ETHTOOL_LINK_EXT_SUBSTATE_BSI_LARGE_NUMBER_OF_PHYSICAL_ERRORS``    Large number of physical
                                                                       errors

  ``ETHTOOL_LINK_EXT_SUBSTATE_BSI_UNSUPPORTED_RATE``                   The system attempted to
                                                                       operate the cable at a rate
                                                                       that is not formally
                                                                       supported, which led to
                                                                       signal integrity issues

  ``ETHTOOL_LINK_EXT_SUBSTATE_BSI_SERDES_REFERENCE_CLOCK_LOST``        The external clock signal for
                                                                       SerDes is too weak or
                                                                       unavailable.

  ``ETHTOOL_LINK_EXT_SUBSTATE_BSI_SERDES_ALOS``                        The received signal for
                                                                       SerDes is too weak because
                                                                       analog loss of signal.
  =================================================================    =============================

  Cable issue substates:

  ===================================================   ============================================
  ``ETHTOOL_LINK_EXT_SUBSTATE_CI_UNSUPPORTED_CABLE``    Unsupported cable

  ``ETHTOOL_LINK_EXT_SUBSTATE_CI_CABLE_TEST_FAILURE``   Cable test failure
  ===================================================   ============================================

  Transceiver module issue substates:

  ===================================================   ============================================
  ``ETHTOOL_LINK_EXT_SUBSTATE_MODULE_CMIS_NOT_READY``   The CMIS Module State Machine did not reach
                                                        the ModuleReady state. For example, if the
                                                        module is stuck at ModuleFault state
  ===================================================   ============================================

DEBUG_GET
=========

Requests debugging settings of a device. At the moment, only message mask is
provided.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_DEBUG_HEADER``            nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_DEBUG_HEADER``            nested  reply header
  ``ETHTOOL_A_DEBUG_MSGMASK``           bitset  message mask
  ====================================  ======  ==========================

The message mask (``ETHTOOL_A_DEBUG_MSGMASK``) is equal to message level as
provided by ``ETHTOOL_GMSGLVL`` and set by ``ETHTOOL_SMSGLVL`` in ioctl
interface. While it is called message level there for historical reasons, most
drivers and almost all newer drivers use it as a mask of enabled message
classes (represented by ``NETIF_MSG_*`` constants); therefore netlink
interface follows its actual use in practice.

``DEBUG_GET`` allows dump requests (kernel returns reply messages for all
devices supporting the request).

DEBUG_SET
=========

Set or update debugging settings of a device. At the moment, only message mask
is supported.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_DEBUG_HEADER``            nested  request header
  ``ETHTOOL_A_DEBUG_MSGMASK``           bitset  message mask
  ====================================  ======  ==========================

``ETHTOOL_A_DEBUG_MSGMASK`` bit set allows setting or modifying mask of
enabled debugging message types for the device.

WOL_GET
=======

Query device wake-on-lan settings. Unlike most "GET" type requests,
``ETHTOOL_MSG_WOL_GET`` requires (netns) ``CAP_NET_ADMIN`` privileges as it
(potentially) provides SecureOn(tm) password which is confidential.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_WOL_HEADER``              nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_WOL_HEADER``              nested  reply header
  ``ETHTOOL_A_WOL_MODES``               bitset  mask of enabled WoL modes
  ``ETHTOOL_A_WOL_SOPASS``              binary  SecureOn(tm) password
  ====================================  ======  ==========================

In reply, ``ETHTOOL_A_WOL_MODES`` mask consists of modes supported by the
device, value of modes which are enabled. ``ETHTOOL_A_WOL_SOPASS`` is only
included in reply if ``WAKE_MAGICSECURE`` mode is supported.

WOL_SET
=======

Set or update wake-on-lan settings.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_WOL_HEADER``              nested  request header
  ``ETHTOOL_A_WOL_MODES``               bitset  enabled WoL modes
  ``ETHTOOL_A_WOL_SOPASS``              binary  SecureOn(tm) password
  ====================================  ======  ==========================

``ETHTOOL_A_WOL_SOPASS`` is only allowed for devices supporting
``WAKE_MAGICSECURE`` mode.

FEATURES_GET
============

Gets netdev features like ``ETHTOOL_GFEATURES`` ioctl request.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_FEATURES_HEADER``         nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_FEATURES_HEADER``         nested  reply header
  ``ETHTOOL_A_FEATURES_HW``             bitset  dev->hw_features
  ``ETHTOOL_A_FEATURES_WANTED``         bitset  dev->wanted_features
  ``ETHTOOL_A_FEATURES_ACTIVE``         bitset  dev->features
  ``ETHTOOL_A_FEATURES_NOCHANGE``       bitset  NETIF_F_NEVER_CHANGE
  ====================================  ======  ==========================

Bitmaps in kernel response have the same meaning as bitmaps used in ioctl
interference but attribute names are different (they are based on
corresponding members of struct net_device). Legacy "flags" are not provided,
if userspace needs them (most likely only ethtool for backward compatibility),
it can calculate their values from related feature bits itself.
ETHA_FEATURES_HW uses mask consisting of all features recognized by kernel (to
provide all names when using verbose bitmap format), the other three use no
mask (simple bit lists).

FEATURES_SET
============

Request to set netdev features like ``ETHTOOL_SFEATURES`` ioctl request.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_FEATURES_HEADER``         nested  request header
  ``ETHTOOL_A_FEATURES_WANTED``         bitset  requested features
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_FEATURES_HEADER``         nested  reply header
  ``ETHTOOL_A_FEATURES_WANTED``         bitset  diff wanted vs. result
  ``ETHTOOL_A_FEATURES_ACTIVE``         bitset  diff old vs. new active
  ====================================  ======  ==========================

Request constains only one bitset which can be either value/mask pair (request
to change specific feature bits and leave the rest) or only a value (request
to set all features to specified set).

As request is subject to netdev_change_features() sanity checks, optional
kernel reply (can be suppressed by ``ETHTOOL_FLAG_OMIT_REPLY`` flag in request
header) informs client about the actual result. ``ETHTOOL_A_FEATURES_WANTED``
reports the difference between client request and actual result: mask consists
of bits which differ between requested features and result (dev->features
after the operation), value consists of values of these bits in the request
(i.e. negated values from resulting features). ``ETHTOOL_A_FEATURES_ACTIVE``
reports the difference between old and new dev->features: mask consists of
bits which have changed, values are their values in new dev->features (after
the operation).

``ETHTOOL_MSG_FEATURES_NTF`` notification is sent not only if device features
are modified using ``ETHTOOL_MSG_FEATURES_SET`` request or on of ethtool ioctl
request but also each time features are modified with netdev_update_features()
or netdev_change_features().

PRIVFLAGS_GET
=============

Gets private flags like ``ETHTOOL_GPFLAGS`` ioctl request.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_PRIVFLAGS_HEADER``        nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_PRIVFLAGS_HEADER``        nested  reply header
  ``ETHTOOL_A_PRIVFLAGS_FLAGS``         bitset  private flags
  ====================================  ======  ==========================

``ETHTOOL_A_PRIVFLAGS_FLAGS`` is a bitset with values of device private flags.
These flags are defined by driver, their number and names (and also meaning)
are device dependent. For compact bitset format, names can be retrieved as
``ETH_SS_PRIV_FLAGS`` string set. If verbose bitset format is requested,
response uses all private flags supported by the device as mask so that client
gets the full information without having to fetch the string set with names.

PRIVFLAGS_SET
=============

Sets or modifies values of device private flags like ``ETHTOOL_SPFLAGS``
ioctl request.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_PRIVFLAGS_HEADER``        nested  request header
  ``ETHTOOL_A_PRIVFLAGS_FLAGS``         bitset  private flags
  ====================================  ======  ==========================

``ETHTOOL_A_PRIVFLAGS_FLAGS`` can either set the whole set of private flags or
modify only values of some of them.

RINGS_GET
=========

Gets ring sizes like ``ETHTOOL_GRINGPARAM`` ioctl request.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_RINGS_HEADER``            nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ===========================
  ``ETHTOOL_A_RINGS_HEADER``            nested  reply header
  ``ETHTOOL_A_RINGS_RX_MAX``            u32     max size of RX ring
  ``ETHTOOL_A_RINGS_RX_MINI_MAX``       u32     max size of RX mini ring
  ``ETHTOOL_A_RINGS_RX_JUMBO_MAX``      u32     max size of RX jumbo ring
  ``ETHTOOL_A_RINGS_TX_MAX``            u32     max size of TX ring
  ``ETHTOOL_A_RINGS_RX``                u32     size of RX ring
  ``ETHTOOL_A_RINGS_RX_MINI``           u32     size of RX mini ring
  ``ETHTOOL_A_RINGS_RX_JUMBO``          u32     size of RX jumbo ring
  ``ETHTOOL_A_RINGS_TX``                u32     size of TX ring
  ``ETHTOOL_A_RINGS_RX_BUF_LEN``        u32     size of buffers on the ring
  ``ETHTOOL_A_RINGS_TCP_DATA_SPLIT``    u8      TCP header / data split
  ``ETHTOOL_A_RINGS_CQE_SIZE``          u32     Size of TX/RX CQE
  ``ETHTOOL_A_RINGS_TX_PUSH``           u8      flag of TX Push mode
  ====================================  ======  ===========================

``ETHTOOL_A_RINGS_TCP_DATA_SPLIT`` indicates whether the device is usable with
page-flipping TCP zero-copy receive (``getsockopt(TCP_ZEROCOPY_RECEIVE)``).
If enabled the device is configured to place frame headers and data into
separate buffers. The device configuration must make it possible to receive
full memory pages of data, for example because MTU is high enough or through
HW-GRO.

``ETHTOOL_A_RINGS_TX_PUSH`` flag is used to enable descriptor fast
path to send packets. In ordinary path, driver fills descriptors in DRAM and
notifies NIC hardware. In fast path, driver pushes descriptors to the device
through MMIO writes, thus reducing the latency. However, enabling this feature
may increase the CPU cost. Drivers may enforce additional per-packet
eligibility checks (e.g. on packet size).

RINGS_SET
=========

Sets ring sizes like ``ETHTOOL_SRINGPARAM`` ioctl request.

Request contents:

  ====================================  ======  ===========================
  ``ETHTOOL_A_RINGS_HEADER``            nested  reply header
  ``ETHTOOL_A_RINGS_RX``                u32     size of RX ring
  ``ETHTOOL_A_RINGS_RX_MINI``           u32     size of RX mini ring
  ``ETHTOOL_A_RINGS_RX_JUMBO``          u32     size of RX jumbo ring
  ``ETHTOOL_A_RINGS_TX``                u32     size of TX ring
  ``ETHTOOL_A_RINGS_RX_BUF_LEN``        u32     size of buffers on the ring
  ``ETHTOOL_A_RINGS_CQE_SIZE``          u32     Size of TX/RX CQE
  ``ETHTOOL_A_RINGS_TX_PUSH``           u8      flag of TX Push mode
  ====================================  ======  ===========================

Kernel checks that requested ring sizes do not exceed limits reported by
driver. Driver may impose additional constraints and may not suspport all
attributes.

``ETHTOOL_A_RINGS_CQE_SIZE`` specifies the completion queue event size.
Completion queue events(CQE) are the events posted by NIC to indicate the
completion status of a packet when the packet is sent(like send success or
error) or received(like pointers to packet fragments). The CQE size parameter
enables to modify the CQE size other than default size if NIC supports it.
A bigger CQE can have more receive buffer pointers inturn NIC can transfer
a bigger frame from wire. Based on the NIC hardware, the overall completion
queue size can be adjusted in the driver if CQE size is modified.

CHANNELS_GET
============

Gets channel counts like ``ETHTOOL_GCHANNELS`` ioctl request.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_CHANNELS_HEADER``         nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_CHANNELS_HEADER``          nested  reply header
  ``ETHTOOL_A_CHANNELS_RX_MAX``          u32     max receive channels
  ``ETHTOOL_A_CHANNELS_TX_MAX``          u32     max transmit channels
  ``ETHTOOL_A_CHANNELS_OTHER_MAX``       u32     max other channels
  ``ETHTOOL_A_CHANNELS_COMBINED_MAX``    u32     max combined channels
  ``ETHTOOL_A_CHANNELS_RX_COUNT``        u32     receive channel count
  ``ETHTOOL_A_CHANNELS_TX_COUNT``        u32     transmit channel count
  ``ETHTOOL_A_CHANNELS_OTHER_COUNT``     u32     other channel count
  ``ETHTOOL_A_CHANNELS_COMBINED_COUNT``  u32     combined channel count
  =====================================  ======  ==========================

CHANNELS_SET
============

Sets channel counts like ``ETHTOOL_SCHANNELS`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_CHANNELS_HEADER``          nested  request header
  ``ETHTOOL_A_CHANNELS_RX_COUNT``        u32     receive channel count
  ``ETHTOOL_A_CHANNELS_TX_COUNT``        u32     transmit channel count
  ``ETHTOOL_A_CHANNELS_OTHER_COUNT``     u32     other channel count
  ``ETHTOOL_A_CHANNELS_COMBINED_COUNT``  u32     combined channel count
  =====================================  ======  ==========================

Kernel checks that requested channel counts do not exceed limits reported by
driver. Driver may impose additional constraints and may not suspport all
attributes.

COALESCE_GET
============

Gets coalescing parameters like ``ETHTOOL_GCOALESCE`` ioctl request.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_COALESCE_HEADER``         nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ===========================================  ======  =======================
  ``ETHTOOL_A_COALESCE_HEADER``                nested  reply header
  ``ETHTOOL_A_COALESCE_RX_USECS``              u32     delay (us), normal Rx
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES``         u32     max packets, normal Rx
  ``ETHTOOL_A_COALESCE_RX_USECS_IRQ``          u32     delay (us), Rx in IRQ
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES_IRQ``     u32     max packets, Rx in IRQ
  ``ETHTOOL_A_COALESCE_TX_USECS``              u32     delay (us), normal Tx
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES``         u32     max packets, normal Tx
  ``ETHTOOL_A_COALESCE_TX_USECS_IRQ``          u32     delay (us), Tx in IRQ
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_IRQ``     u32     IRQ packets, Tx in IRQ
  ``ETHTOOL_A_COALESCE_STATS_BLOCK_USECS``     u32     delay of stats update
  ``ETHTOOL_A_COALESCE_USE_ADAPTIVE_RX``       bool    adaptive Rx coalesce
  ``ETHTOOL_A_COALESCE_USE_ADAPTIVE_TX``       bool    adaptive Tx coalesce
  ``ETHTOOL_A_COALESCE_PKT_RATE_LOW``          u32     threshold for low rate
  ``ETHTOOL_A_COALESCE_RX_USECS_LOW``          u32     delay (us), low Rx
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES_LOW``     u32     max packets, low Rx
  ``ETHTOOL_A_COALESCE_TX_USECS_LOW``          u32     delay (us), low Tx
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_LOW``     u32     max packets, low Tx
  ``ETHTOOL_A_COALESCE_PKT_RATE_HIGH``         u32     threshold for high rate
  ``ETHTOOL_A_COALESCE_RX_USECS_HIGH``         u32     delay (us), high Rx
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES_HIGH``    u32     max packets, high Rx
  ``ETHTOOL_A_COALESCE_TX_USECS_HIGH``         u32     delay (us), high Tx
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_HIGH``    u32     max packets, high Tx
  ``ETHTOOL_A_COALESCE_RATE_SAMPLE_INTERVAL``  u32     rate sampling interval
  ``ETHTOOL_A_COALESCE_USE_CQE_TX``            bool    timer reset mode, Tx
  ``ETHTOOL_A_COALESCE_USE_CQE_RX``            bool    timer reset mode, Rx
  ===========================================  ======  =======================

Attributes are only included in reply if their value is not zero or the
corresponding bit in ``ethtool_ops::supported_coalesce_params`` is set (i.e.
they are declared as supported by driver).

Timer reset mode (``ETHTOOL_A_COALESCE_USE_CQE_TX`` and
``ETHTOOL_A_COALESCE_USE_CQE_RX``) controls the interaction between packet
arrival and the various time based delay parameters. By default timers are
expected to limit the max delay between any packet arrival/departure and a
corresponding interrupt. In this mode timer should be started by packet
arrival (sometimes delivery of previous interrupt) and reset when interrupt
is delivered.
Setting the appropriate attribute to 1 will enable ``CQE`` mode, where
each packet event resets the timer. In this mode timer is used to force
the interrupt if queue goes idle, while busy queues depend on the packet
limit to trigger interrupts.

COALESCE_SET
============

Sets coalescing parameters like ``ETHTOOL_SCOALESCE`` ioctl request.

Request contents:

  ===========================================  ======  =======================
  ``ETHTOOL_A_COALESCE_HEADER``                nested  request header
  ``ETHTOOL_A_COALESCE_RX_USECS``              u32     delay (us), normal Rx
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES``         u32     max packets, normal Rx
  ``ETHTOOL_A_COALESCE_RX_USECS_IRQ``          u32     delay (us), Rx in IRQ
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES_IRQ``     u32     max packets, Rx in IRQ
  ``ETHTOOL_A_COALESCE_TX_USECS``              u32     delay (us), normal Tx
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES``         u32     max packets, normal Tx
  ``ETHTOOL_A_COALESCE_TX_USECS_IRQ``          u32     delay (us), Tx in IRQ
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_IRQ``     u32     IRQ packets, Tx in IRQ
  ``ETHTOOL_A_COALESCE_STATS_BLOCK_USECS``     u32     delay of stats update
  ``ETHTOOL_A_COALESCE_USE_ADAPTIVE_RX``       bool    adaptive Rx coalesce
  ``ETHTOOL_A_COALESCE_USE_ADAPTIVE_TX``       bool    adaptive Tx coalesce
  ``ETHTOOL_A_COALESCE_PKT_RATE_LOW``          u32     threshold for low rate
  ``ETHTOOL_A_COALESCE_RX_USECS_LOW``          u32     delay (us), low Rx
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES_LOW``     u32     max packets, low Rx
  ``ETHTOOL_A_COALESCE_TX_USECS_LOW``          u32     delay (us), low Tx
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_LOW``     u32     max packets, low Tx
  ``ETHTOOL_A_COALESCE_PKT_RATE_HIGH``         u32     threshold for high rate
  ``ETHTOOL_A_COALESCE_RX_USECS_HIGH``         u32     delay (us), high Rx
  ``ETHTOOL_A_COALESCE_RX_MAX_FRAMES_HIGH``    u32     max packets, high Rx
  ``ETHTOOL_A_COALESCE_TX_USECS_HIGH``         u32     delay (us), high Tx
  ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_HIGH``    u32     max packets, high Tx
  ``ETHTOOL_A_COALESCE_RATE_SAMPLE_INTERVAL``  u32     rate sampling interval
  ``ETHTOOL_A_COALESCE_USE_CQE_TX``            bool    timer reset mode, Tx
  ``ETHTOOL_A_COALESCE_USE_CQE_RX``            bool    timer reset mode, Rx
  ===========================================  ======  =======================

Request is rejected if it attributes declared as unsupported by driver (i.e.
such that the corresponding bit in ``ethtool_ops::supported_coalesce_params``
is not set), regardless of their values. Driver may impose additional
constraints on coalescing parameters and their values.

PAUSE_GET
=========

Gets pause frame settings like ``ETHTOOL_GPAUSEPARAM`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_PAUSE_HEADER``             nested  request header
  =====================================  ======  ==========================

Kernel response contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_PAUSE_HEADER``             nested  request header
  ``ETHTOOL_A_PAUSE_AUTONEG``            bool    pause autonegotiation
  ``ETHTOOL_A_PAUSE_RX``                 bool    receive pause frames
  ``ETHTOOL_A_PAUSE_TX``                 bool    transmit pause frames
  ``ETHTOOL_A_PAUSE_STATS``              nested  pause statistics
  =====================================  ======  ==========================

``ETHTOOL_A_PAUSE_STATS`` are reported if ``ETHTOOL_FLAG_STATS`` was set
in ``ETHTOOL_A_HEADER_FLAGS``.
It will be empty if driver did not report any statistics. Drivers fill in
the statistics in the following structure:

.. kernel-doc:: include/linux/ethtool.h
    :identifiers: ethtool_pause_stats

Each member has a corresponding attribute defined.

PAUSE_SET
=========

Sets pause parameters like ``ETHTOOL_GPAUSEPARAM`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_PAUSE_HEADER``             nested  request header
  ``ETHTOOL_A_PAUSE_AUTONEG``            bool    pause autonegotiation
  ``ETHTOOL_A_PAUSE_RX``                 bool    receive pause frames
  ``ETHTOOL_A_PAUSE_TX``                 bool    transmit pause frames
  =====================================  ======  ==========================

EEE_GET
=======

Gets Energy Efficient Ethernet settings like ``ETHTOOL_GEEE`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_EEE_HEADER``               nested  request header
  =====================================  ======  ==========================

Kernel response contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_EEE_HEADER``               nested  request header
  ``ETHTOOL_A_EEE_MODES_OURS``           bool    supported/advertised modes
  ``ETHTOOL_A_EEE_MODES_PEER``           bool    peer advertised link modes
  ``ETHTOOL_A_EEE_ACTIVE``               bool    EEE is actively used
  ``ETHTOOL_A_EEE_ENABLED``              bool    EEE is enabled
  ``ETHTOOL_A_EEE_TX_LPI_ENABLED``       bool    Tx lpi enabled
  ``ETHTOOL_A_EEE_TX_LPI_TIMER``         u32     Tx lpi timeout (in us)
  =====================================  ======  ==========================

In ``ETHTOOL_A_EEE_MODES_OURS``, mask consists of link modes for which EEE is
enabled, value of link modes for which EEE is advertised. Link modes for which
peer advertises EEE are listed in ``ETHTOOL_A_EEE_MODES_PEER`` (no mask). The
netlink interface allows reporting EEE status for all link modes but only
first 32 are provided by the ``ethtool_ops`` callback.

EEE_SET
=======

Sets Energy Efficient Ethernet parameters like ``ETHTOOL_SEEE`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_EEE_HEADER``               nested  request header
  ``ETHTOOL_A_EEE_MODES_OURS``           bool    advertised modes
  ``ETHTOOL_A_EEE_ENABLED``              bool    EEE is enabled
  ``ETHTOOL_A_EEE_TX_LPI_ENABLED``       bool    Tx lpi enabled
  ``ETHTOOL_A_EEE_TX_LPI_TIMER``         u32     Tx lpi timeout (in us)
  =====================================  ======  ==========================

``ETHTOOL_A_EEE_MODES_OURS`` is used to either list link modes to advertise
EEE for (if there is no mask) or specify changes to the list (if there is
a mask). The netlink interface allows reporting EEE status for all link modes
but only first 32 can be set at the moment as that is what the ``ethtool_ops``
callback supports.

TSINFO_GET
==========

Gets timestamping information like ``ETHTOOL_GET_TS_INFO`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_TSINFO_HEADER``            nested  request header
  =====================================  ======  ==========================

Kernel response contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_TSINFO_HEADER``            nested  request header
  ``ETHTOOL_A_TSINFO_TIMESTAMPING``      bitset  SO_TIMESTAMPING flags
  ``ETHTOOL_A_TSINFO_TX_TYPES``          bitset  supported Tx types
  ``ETHTOOL_A_TSINFO_RX_FILTERS``        bitset  supported Rx filters
  ``ETHTOOL_A_TSINFO_PHC_INDEX``         u32     PTP hw clock index
  =====================================  ======  ==========================

``ETHTOOL_A_TSINFO_PHC_INDEX`` is absent if there is no associated PHC (there
is no special value for this case). The bitset attributes are omitted if they
would be empty (no bit set).

CABLE_TEST
==========

Start a cable test.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_CABLE_TEST_HEADER``       nested  request header
  ====================================  ======  ==========================

Notification contents:

An Ethernet cable typically contains 1, 2 or 4 pairs. The length of
the pair can only be measured when there is a fault in the pair and
hence a reflection. Information about the fault may not be available,
depending on the specific hardware. Hence the contents of the notify
message are mostly optional. The attributes can be repeated an
arbitrary number of times, in an arbitrary order, for an arbitrary
number of pairs.

The example shows the notification sent when the test is completed for
a T2 cable, i.e. two pairs. One pair is OK and hence has no length
information. The second pair has a fault and does have length
information.

 +---------------------------------------------+--------+---------------------+
 | ``ETHTOOL_A_CABLE_TEST_HEADER``             | nested | reply header        |
 +---------------------------------------------+--------+---------------------+
 | ``ETHTOOL_A_CABLE_TEST_STATUS``             | u8     | completed           |
 +---------------------------------------------+--------+---------------------+
 | ``ETHTOOL_A_CABLE_TEST_NTF_NEST``           | nested | all the results     |
 +-+-------------------------------------------+--------+---------------------+
 | | ``ETHTOOL_A_CABLE_NEST_RESULT``           | nested | cable test result   |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number         |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_CODE``        | u8     | result code         |
 +-+-+-----------------------------------------+--------+---------------------+
 | | ``ETHTOOL_A_CABLE_NEST_RESULT``           | nested | cable test results  |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number         |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_CODE``        | u8     | result code         |
 +-+-+-----------------------------------------+--------+---------------------+
 | | ``ETHTOOL_A_CABLE_NEST_FAULT_LENGTH``     | nested | cable length        |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_FAULT_LENGTH_PAIR``   | u8     | pair number         |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_FAULT_LENGTH_CM``     | u32    | length in cm        |
 +-+-+-----------------------------------------+--------+---------------------+

CABLE_TEST TDR
==============

Start a cable test and report raw TDR data

Request contents:

 +--------------------------------------------+--------+-----------------------+
 | ``ETHTOOL_A_CABLE_TEST_TDR_HEADER``        | nested | reply header          |
 +--------------------------------------------+--------+-----------------------+
 | ``ETHTOOL_A_CABLE_TEST_TDR_CFG``           | nested | test configuration    |
 +-+------------------------------------------+--------+-----------------------+
 | | ``ETHTOOL_A_CABLE_STEP_FIRST_DISTANCE``  | u32    | first data distance   |
 +-+-+----------------------------------------+--------+-----------------------+
 | | ``ETHTOOL_A_CABLE_STEP_LAST_DISTANCE``   | u32    | last data distance    |
 +-+-+----------------------------------------+--------+-----------------------+
 | | ``ETHTOOL_A_CABLE_STEP_STEP_DISTANCE``   | u32    | distance of each step |
 +-+-+----------------------------------------+--------+-----------------------+
 | | ``ETHTOOL_A_CABLE_TEST_TDR_CFG_PAIR``    | u8     | pair to test          |
 +-+-+----------------------------------------+--------+-----------------------+

The ETHTOOL_A_CABLE_TEST_TDR_CFG is optional, as well as all members
of the nest. All distances are expressed in centimeters. The PHY takes
the distances as a guide, and rounds to the nearest distance it
actually supports. If a pair is passed, only that one pair will be
tested. Otherwise all pairs are tested.

Notification contents:

Raw TDR data is gathered by sending a pulse down the cable and
recording the amplitude of the reflected pulse for a given distance.

It can take a number of seconds to collect TDR data, especial if the
full 100 meters is probed at 1 meter intervals. When the test is
started a notification will be sent containing just
ETHTOOL_A_CABLE_TEST_TDR_STATUS with the value
ETHTOOL_A_CABLE_TEST_NTF_STATUS_STARTED.

When the test has completed a second notification will be sent
containing ETHTOOL_A_CABLE_TEST_TDR_STATUS with the value
ETHTOOL_A_CABLE_TEST_NTF_STATUS_COMPLETED and the TDR data.

The message may optionally contain the amplitude of the pulse send
down the cable. This is measured in mV. A reflection should not be
bigger than transmitted pulse.

Before the raw TDR data should be an ETHTOOL_A_CABLE_TDR_NEST_STEP
nest containing information about the distance along the cable for the
first reading, the last reading, and the step between each
reading. Distances are measured in centimeters. These should be the
exact values the PHY used. These may be different to what the user
requested, if the native measurement resolution is greater than 1 cm.

For each step along the cable, a ETHTOOL_A_CABLE_TDR_NEST_AMPLITUDE is
used to report the amplitude of the reflection for a given pair.

 +---------------------------------------------+--------+----------------------+
 | ``ETHTOOL_A_CABLE_TEST_TDR_HEADER``         | nested | reply header         |
 +---------------------------------------------+--------+----------------------+
 | ``ETHTOOL_A_CABLE_TEST_TDR_STATUS``         | u8     | completed            |
 +---------------------------------------------+--------+----------------------+
 | ``ETHTOOL_A_CABLE_TEST_TDR_NTF_NEST``       | nested | all the results      |
 +-+-------------------------------------------+--------+----------------------+
 | | ``ETHTOOL_A_CABLE_TDR_NEST_PULSE``        | nested | TX Pulse amplitude   |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_PULSE_mV``            | s16    | Pulse amplitude      |
 +-+-+-----------------------------------------+--------+----------------------+
 | | ``ETHTOOL_A_CABLE_NEST_STEP``             | nested | TDR step info        |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_STEP_FIRST_DISTANCE`` | u32    | First data distance  |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_STEP_LAST_DISTANCE``  | u32    | Last data distance   |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_STEP_STEP_DISTANCE``  | u32    | distance of each step|
 +-+-+-----------------------------------------+--------+----------------------+
 | | ``ETHTOOL_A_CABLE_TDR_NEST_AMPLITUDE``    | nested | Reflection amplitude |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number          |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_AMPLITUDE_mV``        | s16    | Reflection amplitude |
 +-+-+-----------------------------------------+--------+----------------------+
 | | ``ETHTOOL_A_CABLE_TDR_NEST_AMPLITUDE``    | nested | Reflection amplitude |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number          |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_AMPLITUDE_mV``        | s16    | Reflection amplitude |
 +-+-+-----------------------------------------+--------+----------------------+
 | | ``ETHTOOL_A_CABLE_TDR_NEST_AMPLITUDE``    | nested | Reflection amplitude |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number          |
 +-+-+-----------------------------------------+--------+----------------------+
 | | | ``ETHTOOL_A_CABLE_AMPLITUDE_mV``        | s16    | Reflection amplitude |
 +-+-+-----------------------------------------+--------+----------------------+

TUNNEL_INFO
===========

Gets information about the tunnel state NIC is aware of.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_TUNNEL_INFO_HEADER``       nested  request header
  =====================================  ======  ==========================

Kernel response contents:

 +---------------------------------------------+--------+---------------------+
 | ``ETHTOOL_A_TUNNEL_INFO_HEADER``            | nested | reply header        |
 +---------------------------------------------+--------+---------------------+
 | ``ETHTOOL_A_TUNNEL_INFO_UDP_PORTS``         | nested | all UDP port tables |
 +-+-------------------------------------------+--------+---------------------+
 | | ``ETHTOOL_A_TUNNEL_UDP_TABLE``            | nested | one UDP port table  |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_TUNNEL_UDP_TABLE_SIZE``     | u32    | max size of the     |
 | | |                                         |        | table               |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_TUNNEL_UDP_TABLE_TYPES``    | bitset | tunnel types which  |
 | | |                                         |        | table can hold      |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_TUNNEL_UDP_TABLE_ENTRY``    | nested | offloaded UDP port  |
 +-+-+-+---------------------------------------+--------+---------------------+
 | | | | ``ETHTOOL_A_TUNNEL_UDP_ENTRY_PORT``   | be16   | UDP port            |
 +-+-+-+---------------------------------------+--------+---------------------+
 | | | | ``ETHTOOL_A_TUNNEL_UDP_ENTRY_TYPE``   | u32    | tunnel type         |
 +-+-+-+---------------------------------------+--------+---------------------+

For UDP tunnel table empty ``ETHTOOL_A_TUNNEL_UDP_TABLE_TYPES`` indicates that
the table contains static entries, hard-coded by the NIC.

FEC_GET
=======

Gets FEC configuration and state like ``ETHTOOL_GFECPARAM`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_FEC_HEADER``               nested  request header
  =====================================  ======  ==========================

Kernel response contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_FEC_HEADER``               nested  request header
  ``ETHTOOL_A_FEC_MODES``                bitset  configured modes
  ``ETHTOOL_A_FEC_AUTO``                 bool    FEC mode auto selection
  ``ETHTOOL_A_FEC_ACTIVE``               u32     index of active FEC mode
  ``ETHTOOL_A_FEC_STATS``                nested  FEC statistics
  =====================================  ======  ==========================

``ETHTOOL_A_FEC_ACTIVE`` is the bit index of the FEC link mode currently
active on the interface. This attribute may not be present if device does
not support FEC.

``ETHTOOL_A_FEC_MODES`` and ``ETHTOOL_A_FEC_AUTO`` are only meaningful when
autonegotiation is disabled. If ``ETHTOOL_A_FEC_AUTO`` is non-zero driver will
select the FEC mode automatically based on the parameters of the SFP module.
This is equivalent to the ``ETHTOOL_FEC_AUTO`` bit of the ioctl interface.
``ETHTOOL_A_FEC_MODES`` carry the current FEC configuration using link mode
bits (rather than old ``ETHTOOL_FEC_*`` bits).

``ETHTOOL_A_FEC_STATS`` are reported if ``ETHTOOL_FLAG_STATS`` was set in
``ETHTOOL_A_HEADER_FLAGS``.
Each attribute carries an array of 64bit statistics. First entry in the array
contains the total number of events on the port, while the following entries
are counters corresponding to lanes/PCS instances. The number of entries in
the array will be:

+--------------+---------------------------------------------+
| `0`          | device does not support FEC statistics      |
+--------------+---------------------------------------------+
| `1`          | device does not support per-lane break down |
+--------------+---------------------------------------------+
| `1 + #lanes` | device has full support for FEC stats       |
+--------------+---------------------------------------------+

Drivers fill in the statistics in the following structure:

.. kernel-doc:: include/linux/ethtool.h
    :identifiers: ethtool_fec_stats

FEC_SET
=======

Sets FEC parameters like ``ETHTOOL_SFECPARAM`` ioctl request.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_FEC_HEADER``               nested  request header
  ``ETHTOOL_A_FEC_MODES``                bitset  configured modes
  ``ETHTOOL_A_FEC_AUTO``                 bool    FEC mode auto selection
  =====================================  ======  ==========================

``FEC_SET`` is only meaningful when autonegotiation is disabled. Otherwise
FEC mode is selected as part of autonegotiation.

``ETHTOOL_A_FEC_MODES`` selects which FEC mode should be used. It's recommended
to set only one bit, if multiple bits are set driver may choose between them
in an implementation specific way.

``ETHTOOL_A_FEC_AUTO`` requests the driver to choose FEC mode based on SFP
module parameters. This does not mean autonegotiation.

MODULE_EEPROM_GET
=================

Fetch module EEPROM data dump.
This interface is designed to allow dumps of at most 1/2 page at once. This
means only dumps of 128 (or less) bytes are allowed, without crossing half page
boundary located at offset 128. For pages other than 0 only high 128 bytes are
accessible.

Request contents:

  =======================================  ======  ==========================
  ``ETHTOOL_A_MODULE_EEPROM_HEADER``       nested  request header
  ``ETHTOOL_A_MODULE_EEPROM_OFFSET``       u32     offset within a page
  ``ETHTOOL_A_MODULE_EEPROM_LENGTH``       u32     amount of bytes to read
  ``ETHTOOL_A_MODULE_EEPROM_PAGE``         u8      page number
  ``ETHTOOL_A_MODULE_EEPROM_BANK``         u8      bank number
  ``ETHTOOL_A_MODULE_EEPROM_I2C_ADDRESS``  u8      page I2C address
  =======================================  ======  ==========================

If ``ETHTOOL_A_MODULE_EEPROM_BANK`` is not specified, bank 0 is assumed.

Kernel response contents:

 +---------------------------------------------+--------+---------------------+
 | ``ETHTOOL_A_MODULE_EEPROM_HEADER``          | nested | reply header        |
 +---------------------------------------------+--------+---------------------+
 | ``ETHTOOL_A_MODULE_EEPROM_DATA``            | binary | array of bytes from |
 |                                             |        | module EEPROM       |
 +---------------------------------------------+--------+---------------------+

``ETHTOOL_A_MODULE_EEPROM_DATA`` has an attribute length equal to the amount of
bytes driver actually read.

STATS_GET
=========

Get standard statistics for the interface. Note that this is not
a re-implementation of ``ETHTOOL_GSTATS`` which exposed driver-defined
stats.

Request contents:

  =======================================  ======  ==========================
  ``ETHTOOL_A_STATS_HEADER``               nested  request header
  ``ETHTOOL_A_STATS_GROUPS``               bitset  requested groups of stats
  =======================================  ======  ==========================

Kernel response contents:

 +-----------------------------------+--------+--------------------------------+
 | ``ETHTOOL_A_STATS_HEADER``        | nested | reply header                   |
 +-----------------------------------+--------+--------------------------------+
 | ``ETHTOOL_A_STATS_GRP``           | nested | one or more group of stats     |
 +-+---------------------------------+--------+--------------------------------+
 | | ``ETHTOOL_A_STATS_GRP_ID``      | u32    | group ID - ``ETHTOOL_STATS_*`` |
 +-+---------------------------------+--------+--------------------------------+
 | | ``ETHTOOL_A_STATS_GRP_SS_ID``   | u32    | string set ID for names        |
 +-+---------------------------------+--------+--------------------------------+
 | | ``ETHTOOL_A_STATS_GRP_STAT``    | nested | nest containing a statistic    |
 +-+---------------------------------+--------+--------------------------------+
 | | ``ETHTOOL_A_STATS_GRP_HIST_RX`` | nested | histogram statistic (Rx)       |
 +-+---------------------------------+--------+--------------------------------+
 | | ``ETHTOOL_A_STATS_GRP_HIST_TX`` | nested | histogram statistic (Tx)       |
 +-+---------------------------------+--------+--------------------------------+

Users specify which groups of statistics they are requesting via
the ``ETHTOOL_A_STATS_GROUPS`` bitset. Currently defined values are:

 ====================== ======== ===============================================
 ETHTOOL_STATS_ETH_MAC  eth-mac  Basic IEEE 802.3 MAC statistics (30.3.1.1.*)
 ETHTOOL_STATS_ETH_PHY  eth-phy  Basic IEEE 802.3 PHY statistics (30.3.2.1.*)
 ETHTOOL_STATS_ETH_CTRL eth-ctrl Basic IEEE 802.3 MAC Ctrl statistics (30.3.3.*)
 ETHTOOL_STATS_RMON     rmon     RMON (RFC 2819) statistics
 ====================== ======== ===============================================

Each group should have a corresponding ``ETHTOOL_A_STATS_GRP`` in the reply.
``ETHTOOL_A_STATS_GRP_ID`` identifies which group's statistics nest contains.
``ETHTOOL_A_STATS_GRP_SS_ID`` identifies the string set ID for the names of
the statistics in the group, if available.

Statistics are added to the ``ETHTOOL_A_STATS_GRP`` nest under
``ETHTOOL_A_STATS_GRP_STAT``. ``ETHTOOL_A_STATS_GRP_STAT`` should contain
single 8 byte (u64) attribute inside - the type of that attribute is
the statistic ID and the value is the value of the statistic.
Each group has its own interpretation of statistic IDs.
Attribute IDs correspond to strings from the string set identified
by ``ETHTOOL_A_STATS_GRP_SS_ID``. Complex statistics (such as RMON histogram
entries) are also listed inside ``ETHTOOL_A_STATS_GRP`` and do not have
a string defined in the string set.

RMON "histogram" counters count number of packets within given size range.
Because RFC does not specify the ranges beyond the standard 1518 MTU devices
differ in definition of buckets. For this reason the definition of packet ranges
is left to each driver.

``ETHTOOL_A_STATS_GRP_HIST_RX`` and ``ETHTOOL_A_STATS_GRP_HIST_TX`` nests
contain the following attributes:

 ================================= ====== ===================================
 ETHTOOL_A_STATS_RMON_HIST_BKT_LOW u32    low bound of the packet size bucket
 ETHTOOL_A_STATS_RMON_HIST_BKT_HI  u32    high bound of the bucket
 ETHTOOL_A_STATS_RMON_HIST_VAL     u64    packet counter
 ================================= ====== ===================================

Low and high bounds are inclusive, for example:

 ============================= ==== ====
 RFC statistic                 low  high
 ============================= ==== ====
 etherStatsPkts64Octets          0    64
 etherStatsPkts512to1023Octets 512  1023
 ============================= ==== ====

PHC_VCLOCKS_GET
===============

Query device PHC virtual clocks information.

Request contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_PHC_VCLOCKS_HEADER``      nested  request header
  ====================================  ======  ==========================

Kernel response contents:

  ====================================  ======  ==========================
  ``ETHTOOL_A_PHC_VCLOCKS_HEADER``      nested  reply header
  ``ETHTOOL_A_PHC_VCLOCKS_NUM``         u32     PHC virtual clocks number
  ``ETHTOOL_A_PHC_VCLOCKS_INDEX``       s32     PHC index array
  ====================================  ======  ==========================

MODULE_GET
==========

Gets transceiver module parameters.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_MODULE_HEADER``            nested  request header
  =====================================  ======  ==========================

Kernel response contents:

  ======================================  ======  ==========================
  ``ETHTOOL_A_MODULE_HEADER``             nested  reply header
  ``ETHTOOL_A_MODULE_POWER_MODE_POLICY``  u8      power mode policy
  ``ETHTOOL_A_MODULE_POWER_MODE``         u8      operational power mode
  ======================================  ======  ==========================

The optional ``ETHTOOL_A_MODULE_POWER_MODE_POLICY`` attribute encodes the
transceiver module power mode policy enforced by the host. The default policy
is driver-dependent, but "auto" is the recommended default and it should be
implemented by new drivers and drivers where conformance to a legacy behavior
is not critical.

The optional ``ETHTHOOL_A_MODULE_POWER_MODE`` attribute encodes the operational
power mode policy of the transceiver module. It is only reported when a module
is plugged-in. Possible values are:

.. kernel-doc:: include/uapi/linux/ethtool.h
    :identifiers: ethtool_module_power_mode

MODULE_SET
==========

Sets transceiver module parameters.

Request contents:

  ======================================  ======  ==========================
  ``ETHTOOL_A_MODULE_HEADER``             nested  request header
  ``ETHTOOL_A_MODULE_POWER_MODE_POLICY``  u8      power mode policy
  ======================================  ======  ==========================

When set, the optional ``ETHTOOL_A_MODULE_POWER_MODE_POLICY`` attribute is used
to set the transceiver module power policy enforced by the host. Possible
values are:

.. kernel-doc:: include/uapi/linux/ethtool.h
    :identifiers: ethtool_module_power_mode_policy

For SFF-8636 modules, low power mode is forced by the host according to table
6-10 in revision 2.10a of the specification.

For CMIS modules, low power mode is forced by the host according to table 6-12
in revision 5.0 of the specification.

PSE_GET
=======

Gets PSE attributes.

Request contents:

  =====================================  ======  ==========================
  ``ETHTOOL_A_PSE_HEADER``               nested  request header
  =====================================  ======  ==========================

Kernel response contents:

  ======================================  ======  =============================
  ``ETHTOOL_A_PSE_HEADER``                nested  reply header
  ``ETHTOOL_A_PODL_PSE_ADMIN_STATE``         u32  Operational state of the PoDL
                                                  PSE functions
  ``ETHTOOL_A_PODL_PSE_PW_D_STATUS``         u32  power detection status of the
                                                  PoDL PSE.
  ======================================  ======  =============================

When set, the optional ``ETHTOOL_A_PODL_PSE_ADMIN_STATE`` attribute identifies
the operational state of the PoDL PSE functions.  The operational state of the
PSE function can be changed using the ``ETHTOOL_A_PODL_PSE_ADMIN_CONTROL``
action. This option is corresponding to ``IEEE 802.3-2018`` 30.15.1.1.2
aPoDLPSEAdminState. Possible values are:

.. kernel-doc:: include/uapi/linux/ethtool.h
    :identifiers: ethtool_podl_pse_admin_state

When set, the optional ``ETHTOOL_A_PODL_PSE_PW_D_STATUS`` attribute identifies
the power detection status of the PoDL PSE.  The status depend on internal PSE
state machine and automatic PD classification support. This option is
corresponding to ``IEEE 802.3-2018`` 30.15.1.1.3 aPoDLPSEPowerDetectionStatus.
Possible values are:

.. kernel-doc:: include/uapi/linux/ethtool.h
    :identifiers: ethtool_podl_pse_pw_d_status

PSE_SET
=======

Sets PSE parameters.

Request contents:

  ======================================  ======  =============================
  ``ETHTOOL_A_PSE_HEADER``                nested  request header
  ``ETHTOOL_A_PODL_PSE_ADMIN_CONTROL``       u32  Control PoDL PSE Admin state
  ======================================  ======  =============================

When set, the optional ``ETHTOOL_A_PODL_PSE_ADMIN_CONTROL`` attribute is used
to control PoDL PSE Admin functions. This option is implementing
``IEEE 802.3-2018`` 30.15.1.2.1 acPoDLPSEAdminControl. See
``ETHTOOL_A_PODL_PSE_ADMIN_STATE`` for supported values.

RSS_GET
=======

Get indirection table, hash key and hash function info associated with a
RSS context of an interface similar to ``ETHTOOL_GRSSH`` ioctl request.

Request contents:

=====================================  ======  ==========================
  ``ETHTOOL_A_RSS_HEADER``             nested  request header
  ``ETHTOOL_A_RSS_CONTEXT``            u32     context number
=====================================  ======  ==========================

Kernel response contents:

=====================================  ======  ==========================
  ``ETHTOOL_A_RSS_HEADER``             nested  reply header
  ``ETHTOOL_A_RSS_HFUNC``              u32     RSS hash func
  ``ETHTOOL_A_RSS_INDIR``              binary  Indir table bytes
  ``ETHTOOL_A_RSS_HKEY``               binary  Hash key bytes
=====================================  ======  ==========================

ETHTOOL_A_RSS_HFUNC attribute is bitmap indicating the hash function
being used. Current supported options are toeplitz, xor or crc32.
ETHTOOL_A_RSS_INDIR attribute returns RSS indrection table where each byte
indicates queue number.

Request translation
===================

The following table maps ioctl commands to netlink commands providing their
functionality. Entries with "n/a" in right column are commands which do not
have their netlink replacement yet. Entries which "n/a" in the left column
are netlink only.

  =================================== =====================================
  ioctl command                       netlink command
  =================================== =====================================
  ``ETHTOOL_GSET``                    ``ETHTOOL_MSG_LINKINFO_GET``
                                      ``ETHTOOL_MSG_LINKMODES_GET``
  ``ETHTOOL_SSET``                    ``ETHTOOL_MSG_LINKINFO_SET``
                                      ``ETHTOOL_MSG_LINKMODES_SET``
  ``ETHTOOL_GDRVINFO``                n/a
  ``ETHTOOL_GREGS``                   n/a
  ``ETHTOOL_GWOL``                    ``ETHTOOL_MSG_WOL_GET``
  ``ETHTOOL_SWOL``                    ``ETHTOOL_MSG_WOL_SET``
  ``ETHTOOL_GMSGLVL``                 ``ETHTOOL_MSG_DEBUG_GET``
  ``ETHTOOL_SMSGLVL``                 ``ETHTOOL_MSG_DEBUG_SET``
  ``ETHTOOL_NWAY_RST``                n/a
  ``ETHTOOL_GLINK``                   ``ETHTOOL_MSG_LINKSTATE_GET``
  ``ETHTOOL_GEEPROM``                 n/a
  ``ETHTOOL_SEEPROM``                 n/a
  ``ETHTOOL_GCOALESCE``               ``ETHTOOL_MSG_COALESCE_GET``
  ``ETHTOOL_SCOALESCE``               ``ETHTOOL_MSG_COALESCE_SET``
  ``ETHTOOL_GRINGPARAM``              ``ETHTOOL_MSG_RINGS_GET``
  ``ETHTOOL_SRINGPARAM``              ``ETHTOOL_MSG_RINGS_SET``
  ``ETHTOOL_GPAUSEPARAM``             ``ETHTOOL_MSG_PAUSE_GET``
  ``ETHTOOL_SPAUSEPARAM``             ``ETHTOOL_MSG_PAUSE_SET``
  ``ETHTOOL_GRXCSUM``                 ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_SRXCSUM``                 ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GTXCSUM``                 ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_STXCSUM``                 ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GSG``                     ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_SSG``                     ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_TEST``                    n/a
  ``ETHTOOL_GSTRINGS``                ``ETHTOOL_MSG_STRSET_GET``
  ``ETHTOOL_PHYS_ID``                 n/a
  ``ETHTOOL_GSTATS``                  n/a
  ``ETHTOOL_GTSO``                    ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_STSO``                    ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GPERMADDR``               rtnetlink ``RTM_GETLINK``
  ``ETHTOOL_GUFO``                    ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_SUFO``                    ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GGSO``                    ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_SGSO``                    ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GFLAGS``                  ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_SFLAGS``                  ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GPFLAGS``                 ``ETHTOOL_MSG_PRIVFLAGS_GET``
  ``ETHTOOL_SPFLAGS``                 ``ETHTOOL_MSG_PRIVFLAGS_SET``
  ``ETHTOOL_GRXFH``                   n/a
  ``ETHTOOL_SRXFH``                   n/a
  ``ETHTOOL_GGRO``                    ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_SGRO``                    ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GRXRINGS``                n/a
  ``ETHTOOL_GRXCLSRLCNT``             n/a
  ``ETHTOOL_GRXCLSRULE``              n/a
  ``ETHTOOL_GRXCLSRLALL``             n/a
  ``ETHTOOL_SRXCLSRLDEL``             n/a
  ``ETHTOOL_SRXCLSRLINS``             n/a
  ``ETHTOOL_FLASHDEV``                n/a
  ``ETHTOOL_RESET``                   n/a
  ``ETHTOOL_SRXNTUPLE``               n/a
  ``ETHTOOL_GRXNTUPLE``               n/a
  ``ETHTOOL_GSSET_INFO``              ``ETHTOOL_MSG_STRSET_GET``
  ``ETHTOOL_GRXFHINDIR``              n/a
  ``ETHTOOL_SRXFHINDIR``              n/a
  ``ETHTOOL_GFEATURES``               ``ETHTOOL_MSG_FEATURES_GET``
  ``ETHTOOL_SFEATURES``               ``ETHTOOL_MSG_FEATURES_SET``
  ``ETHTOOL_GCHANNELS``               ``ETHTOOL_MSG_CHANNELS_GET``
  ``ETHTOOL_SCHANNELS``               ``ETHTOOL_MSG_CHANNELS_SET``
  ``ETHTOOL_SET_DUMP``                n/a
  ``ETHTOOL_GET_DUMP_FLAG``           n/a
  ``ETHTOOL_GET_DUMP_DATA``           n/a
  ``ETHTOOL_GET_TS_INFO``             ``ETHTOOL_MSG_TSINFO_GET``
  ``ETHTOOL_GMODULEINFO``             ``ETHTOOL_MSG_MODULE_EEPROM_GET``
  ``ETHTOOL_GMODULEEEPROM``           ``ETHTOOL_MSG_MODULE_EEPROM_GET``
  ``ETHTOOL_GEEE``                    ``ETHTOOL_MSG_EEE_GET``
  ``ETHTOOL_SEEE``                    ``ETHTOOL_MSG_EEE_SET``
  ``ETHTOOL_GRSSH``                   ``ETHTOOL_MSG_RSS_GET``
  ``ETHTOOL_SRSSH``                   n/a
  ``ETHTOOL_GTUNABLE``                n/a
  ``ETHTOOL_STUNABLE``                n/a
  ``ETHTOOL_GPHYSTATS``               n/a
  ``ETHTOOL_PERQUEUE``                n/a
  ``ETHTOOL_GLINKSETTINGS``           ``ETHTOOL_MSG_LINKINFO_GET``
                                      ``ETHTOOL_MSG_LINKMODES_GET``
  ``ETHTOOL_SLINKSETTINGS``           ``ETHTOOL_MSG_LINKINFO_SET``
                                      ``ETHTOOL_MSG_LINKMODES_SET``
  ``ETHTOOL_PHY_GTUNABLE``            n/a
  ``ETHTOOL_PHY_STUNABLE``            n/a
  ``ETHTOOL_GFECPARAM``               ``ETHTOOL_MSG_FEC_GET``
  ``ETHTOOL_SFECPARAM``               ``ETHTOOL_MSG_FEC_SET``
  n/a                                 ``ETHTOOL_MSG_CABLE_TEST_ACT``
  n/a                                 ``ETHTOOL_MSG_CABLE_TEST_TDR_ACT``
  n/a                                 ``ETHTOOL_MSG_TUNNEL_INFO_GET``
  n/a                                 ``ETHTOOL_MSG_PHC_VCLOCKS_GET``
  n/a                                 ``ETHTOOL_MSG_MODULE_GET``
  n/a                                 ``ETHTOOL_MSG_MODULE_SET``
  =================================== =====================================

repo_name: angery/linux


code:
.. SPDX-License-Identifier: GPL-2.0

========
FAILOVER
========

Overview
========

The failover module provides a generic interface for paravirtual drivers
to register a netdev and a set of ops with a failover instance. The ops
are used as event handlers that get called to handle netdev register/
unregister/link change/name change events on slave pci ethernet devices
with the same mac address as the failover netdev.

This enables paravirtual drivers to use a VF as an accelerated low latency
datapath. It also allows live migration of VMs with direct attached VFs by
failing over to the paravirtual datapath when the VF is unplugged.


code:
.. SPDX-License-Identifier: GPL-2.0

============================
LC-trie implementation notes
============================

Node types
----------
leaf
	An end node with data. This has a copy of the relevant key, along
	with 'hlist' with routing table entries sorted by prefix length.
	See struct leaf and struct leaf_info.

trie node or tnode
	An internal node, holding an array of child (leaf or tnode) pointers,
	indexed	through a subset of the key. See Level Compression.

A few concepts explained
------------------------
Bits (tnode)
	The number of bits in the key segment used for indexing into the
	child array - the "child index". See Level Compression.

Pos (tnode)
	The position (in the key) of the key segment used for indexing into
	the child array. See Path Compression.

Path Compression / skipped bits
	Any given tnode is linked to from the child array of its parent, using
	a segment of the key specified by the parent's "pos" and "bits"
	In certain cases, this tnode's own "pos" will not be immediately
	adjacent to the parent (pos+bits), but there will be some bits
	in the key skipped over because they represent a single path with no
	deviations. These "skipped bits" constitute Path Compression.
	Note that the search algorithm will simply skip over these bits when
	searching, making it necessary to save the keys in the leaves to
	verify that they actually do match the key we are searching for.

Level Compression / child arrays
	the trie is kept level balanced moving, under certain conditions, the
	children of a full child (see "full_children") up one level, so that
	instead of a pure binary tree, each internal node ("tnode") may
	contain an arbitrarily large array of links to several children.
	Conversely, a tnode with a mostly empty	child array (see empty_children)
	may be "halved", having some of its children moved downwards one level,
	in order to avoid ever-increasing child arrays.

empty_children
	the number of positions in the child array of a given tnode that are
	NULL.

full_children
	the number of children of a given tnode that aren't path compressed.
	(in other words, they aren't NULL or leaves and their "pos" is equal
	to this	tnode's "pos"+"bits").

	(The word "full" here is used more in the sense of "complete" than
	as the opposite of "empty", which might be a tad confusing.)

Comments
---------

We have tried to keep the structure of the code as close to fib_hash as
possible to allow verification and help up reviewing.

fib_find_node()
	A good start for understanding this code. This function implements a
	straightforward trie lookup.

fib_insert_node()
	Inserts a new leaf node in the trie. This is bit more complicated than
	fib_find_node(). Inserting a new node means we might have to run the
	level compression algorithm on part of the trie.

trie_leaf_remove()
	Looks up a key, deletes it and runs the level compression algorithm.

trie_rebalance()
	The key function for the dynamic trie after any change in the trie
	it is run to optimize and reorganize. It will walk the trie upwards
	towards the root from a given tnode, doing a resize() at each step
	to implement level compression.

resize()
	Analyzes a tnode and optimizes the child array size by either inflating
	or shrinking it repeatedly until it fulfills the criteria for optimal
	level compression. This part follows the original paper pretty closely
	and there may be some room for experimentation here.

inflate()
	Doubles the size of the child array within a tnode. Used by resize().

halve()
	Halves the size of the child array within a tnode - the inverse of
	inflate(). Used by resize();

fn_trie_insert(), fn_trie_delete(), fn_trie_select_default()
	The route manipulation functions. Should conform pretty closely to the
	corresponding functions in fib_hash.

fn_trie_flush()
	This walks the full trie (using nextleaf()) and searches for empty
	leaves which have to be removed.

fn_trie_dump()
	Dumps the routing table ordered by prefix length. This is somewhat
	slower than the corresponding fib_hash function, as we have to walk the
	entire trie for each prefix length. In comparison, fib_hash is organized
	as one "zone"/hash per prefix length.

Locking
-------

fib_lock is used for an RW-lock in the same way that this is done in fib_hash.
However, the functions are somewhat separated for other possible locking
scenarios. It might conceivably be possible to run trie_rebalance via RCU
to avoid read_lock in the fn_trie_lookup() function.

Main lookup mechanism
---------------------
fn_trie_lookup() is the main lookup function.

The lookup is in its simplest form just like fib_find_node(). We descend the
trie, key segment by key segment, until we find a leaf. check_leaf() does
the fib_semantic_match in the leaf's sorted prefix hlist.

If we find a match, we are done.

If we don't find a match, we enter prefix matching mode. The prefix length,
starting out at the same as the key length, is reduced one step at a time,
and we backtrack upwards through the trie trying to find a longest matching
prefix. The goal is always to reach a leaf and get a positive result from the
fib_semantic_match mechanism.

Inside each tnode, the search for longest matching prefix consists of searching
through the child array, chopping off (zeroing) the least significant "1" of
the child index until we find a match or the child index consists of nothing but
zeros.

At this point we backtrack (t->stats.backtrack++) up the trie, continuing to
chop off part of the key in order to find the longest matching prefix.

At this point we will repeatedly descend subtries to look for a match, and there
are some optimizations available that can provide us with "shortcuts" to avoid
descending into dead ends. Look for "HL_OPTIMIZE" sections in the code.

To alleviate any doubts about the correctness of the route selection process,
a new netlink operation has been added. Look for NETLINK_FIB_LOOKUP, which
gives userland access to fib_lookup().