diff options
Diffstat (limited to 'Documentation/networking/timestamping.txt')
| -rw-r--r-- | Documentation/networking/timestamping.txt | 32 |
1 files changed, 27 insertions, 5 deletions
diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt index 96f50694a748..1be0b6f9e0cb 100644 --- a/Documentation/networking/timestamping.txt +++ b/Documentation/networking/timestamping.txt @@ -44,8 +44,7 @@ timeval of SO_TIMESTAMP (ms). Supports multiple types of timestamp requests. As a result, this socket option takes a bitmap of flags, not a boolean. In - err = setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPING, (void *) val, - sizeof(val)); + err = setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPING, &val, sizeof(val)); val is an integer with any of the following bits set. Setting other bit returns EINVAL and does not change the current state. @@ -193,6 +192,24 @@ SOF_TIMESTAMPING_OPT_STATS: the transmit timestamps, such as how long a certain block of data was limited by peer's receiver window. +SOF_TIMESTAMPING_OPT_PKTINFO: + + Enable the SCM_TIMESTAMPING_PKTINFO control message for incoming + packets with hardware timestamps. The message contains struct + scm_ts_pktinfo, which supplies the index of the real interface which + received the packet and its length at layer 2. A valid (non-zero) + interface index will be returned only if CONFIG_NET_RX_BUSY_POLL is + enabled and the driver is using NAPI. The struct contains also two + other fields, but they are reserved and undefined. + +SOF_TIMESTAMPING_OPT_TX_SWHW: + + Request both hardware and software timestamps for outgoing packets + when SOF_TIMESTAMPING_TX_HARDWARE and SOF_TIMESTAMPING_TX_SOFTWARE + are enabled at the same time. If both timestamps are generated, + two separate messages will be looped to the socket's error queue, + each containing just one timestamp. + 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. @@ -231,8 +248,7 @@ setsockopt to receive timestamps: __u32 val = SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_OPT_ID /* or any other flag */; - err = setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPING, (void *) val, - sizeof(val)); + err = setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPING, &val, sizeof(val)); 1.4 Bytestream Timestamps @@ -312,7 +328,7 @@ struct scm_timestamping { }; The structure can return up to three timestamps. This is a legacy -feature. Only one field is non-zero at any time. Most timestamps +feature. At least one field is non-zero at any time. Most timestamps are passed in ts[0]. Hardware timestamps are passed in ts[2]. ts[1] used to hold hardware timestamps converted to system time. @@ -321,6 +337,12 @@ a HW PTP clock source, to allow time conversion in userspace and optionally synchronize system time with a userspace PTP stack such as linuxptp. For the PTP clock API, see Documentation/ptp/ptp.txt. +Note that if the SO_TIMESTAMP or SO_TIMESTAMPNS option is enabled +together with SO_TIMESTAMPING using SOF_TIMESTAMPING_SOFTWARE, a false +software timestamp will be generated in the recvmsg() call and passed +in ts[0] when a real software timestamp is missing. This happens also +on hardware transmit timestamps. + 2.1.1 Transmit timestamps with MSG_ERRQUEUE For transmit timestamps the outgoing packet is looped back to the |