============================= 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 ```` 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. 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) ================================= =================================== 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 ===================================== ================================ 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 ===================================== ================================ ``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 ==================================== ====== ========================== 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_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 and duplex is specified, kernel adjusts advertised modes to all supported modes matching speed, duplex or both (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. 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. =================================== ===================================== 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`` n/a ``ETHTOOL_SWOL`` n/a ``ETHTOOL_GMSGLVL`` n/a ``ETHTOOL_SMSGLVL`` n/a ``ETHTOOL_NWAY_RST`` n/a ``ETHTOOL_GLINK`` n/a ``ETHTOOL_GEEPROM`` n/a ``ETHTOOL_SEEPROM`` n/a ``ETHTOOL_GCOALESCE`` n/a ``ETHTOOL_SCOALESCE`` n/a ``ETHTOOL_GRINGPARAM`` n/a ``ETHTOOL_SRINGPARAM`` n/a ``ETHTOOL_GPAUSEPARAM`` n/a ``ETHTOOL_SPAUSEPARAM`` n/a ``ETHTOOL_GRXCSUM`` n/a ``ETHTOOL_SRXCSUM`` n/a ``ETHTOOL_GTXCSUM`` n/a ``ETHTOOL_STXCSUM`` n/a ``ETHTOOL_GSG`` n/a ``ETHTOOL_SSG`` n/a ``ETHTOOL_TEST`` n/a ``ETHTOOL_GSTRINGS`` ``ETHTOOL_MSG_STRSET_GET`` ``ETHTOOL_PHYS_ID`` n/a ``ETHTOOL_GSTATS`` n/a ``ETHTOOL_GTSO`` n/a ``ETHTOOL_STSO`` n/a ``ETHTOOL_GPERMADDR`` rtnetlink ``RTM_GETLINK`` ``ETHTOOL_GUFO`` n/a ``ETHTOOL_SUFO`` n/a ``ETHTOOL_GGSO`` n/a ``ETHTOOL_SGSO`` n/a ``ETHTOOL_GFLAGS`` n/a ``ETHTOOL_SFLAGS`` n/a ``ETHTOOL_GPFLAGS`` n/a ``ETHTOOL_SPFLAGS`` n/a ``ETHTOOL_GRXFH`` n/a ``ETHTOOL_SRXFH`` n/a ``ETHTOOL_GGRO`` n/a ``ETHTOOL_SGRO`` n/a ``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`` n/a ``ETHTOOL_SFEATURES`` n/a ``ETHTOOL_GCHANNELS`` n/a ``ETHTOOL_SCHANNELS`` n/a ``ETHTOOL_SET_DUMP`` n/a ``ETHTOOL_GET_DUMP_FLAG`` n/a ``ETHTOOL_GET_DUMP_DATA`` n/a ``ETHTOOL_GET_TS_INFO`` n/a ``ETHTOOL_GMODULEINFO`` n/a ``ETHTOOL_GMODULEEEPROM`` n/a ``ETHTOOL_GEEE`` n/a ``ETHTOOL_SEEE`` n/a ``ETHTOOL_GRSSH`` n/a ``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`` n/a ``ETHTOOL_SFECPARAM`` n/a =================================== =====================================