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| -rw-r--r-- | Documentation/networking/ethtool-netlink.rst | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst index af56c304cef4..32179168eb73 100644 --- a/Documentation/networking/ethtool-netlink.rst +++ b/Documentation/networking/ethtool-netlink.rst @@ -96,7 +96,7 @@ 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). +bits identified by 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 @@ -156,12 +156,16 @@ Bit-by-bit form: nested (bitset) attribute contents: | | | ``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 +For bit-by-bit form, ``ETHTOOL_A_BITSET_SIZE`` is optional, and +``ETHTOOL_A_BITSET_BITS`` is mandatory. ``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. +``ETHTOOL_A_BITSET_BIT_VALUE``, the rest is preserved. + +A request fails if index exceeds kernel bit length or if name is not +recognized. If both name and index are set, the request will fail if they +point to different bits. 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 |