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Diffstat (limited to 'Documentation/networking')
| -rw-r--r-- | Documentation/networking/timestamping.rst | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/networking/timestamping.rst b/Documentation/networking/timestamping.rst index 9c7773271393..8199e6917671 100644 --- a/Documentation/networking/timestamping.rst +++ b/Documentation/networking/timestamping.rst @@ -267,6 +267,23 @@ SOF_TIMESTAMPING_OPT_TX_SWHW: two separate messages will be looped to the socket's error queue, each containing just one timestamp. +SOF_TIMESTAMPING_OPT_RX_FILTER: + Filter out spurious receive timestamps: report a receive timestamp + only if the matching timestamp generation flag is enabled. + + Receive timestamps are generated early in the ingress path, before a + packet's destination socket is known. If any socket enables receive + timestamps, packets for all socket will receive timestamped packets. + Including those that request timestamp reporting with + SOF_TIMESTAMPING_SOFTWARE and/or SOF_TIMESTAMPING_RAW_HARDWARE, but + do not request receive timestamp generation. This can happen when + requesting transmit timestamps only. + + Receiving spurious timestamps is generally benign. A process can + ignore the unexpected non-zero value. But it makes behavior subtly + dependent on other sockets. This flag isolates the socket for more + deterministic behavior. + New applications are encouraged to pass SOF_TIMESTAMPING_OPT_ID to disambiguate timestamps and SOF_TIMESTAMPING_OPT_TSONLY to operate regardless of the setting of sysctl net.core.tstamp_allow_data. |