phc2sys: man page update for -a and -r options
Signed-off-by: Jiri Benc <jbenc@redhat.com>master
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phc2sys.8
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phc2sys.8
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.TH PHC2SYS 8 "November 2012" "linuxptp"
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.SH NAME
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phc2sys \- synchronize two clocks
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phc2sys \- synchronize two or more clocks
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.SH SYNOPSIS
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.B phc2sys \-a
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[
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.B \-r
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] [
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.B \-r
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] [ options ]
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.br
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.B phc2sys
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[
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.B \-wmqvx
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] [
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.BI \-d " pps-device"
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] [
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.BI \-s " device"
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@ -15,45 +20,53 @@ phc2sys \- synchronize two clocks
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] [
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.BI \-O " offset"
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] [
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.BI \-E " servo"
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] [
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.BI \-P " kp"
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] [
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.BI \-I " ki"
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] [
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.BI \-S " step"
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] [
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.BI \-F " step"
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] [
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.BI \-R " update-rate"
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] [
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.BI \-N " clock-readings"
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] [
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.BI \-L " freq-limit"
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] [
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.BI \-u " summary-updates"
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] [
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.BI \-n " domain-number"
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] [
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.BI \-l " print-level"
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]
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.BI \-w
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] [ options ]
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.SH DESCRIPTION
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.B phc2sys
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is a program which synchronizes two clocks in the system. Typically, it is used
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to synchronize the system clock to a PTP hardware clock (PHC), which itself is
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synchronized by the
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is a program which synchronizes two or more clocks in the system. Typically,
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it is used to synchronize the system clock to a PTP hardware clock (PHC),
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which itself is synchronized by the
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.BR ptp4l (8)
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program.
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Two synchronization modes are supported, one uses a pulse per second (PPS)
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With the
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.B \-a
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option, the clocks to synchronize are fetched from the running
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.B ptp4l
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daemon and the direction of synchronization automatically follows changes of
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the PTP port states.
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Manual configuration is also possible. When using manual configuration, two
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synchronization modes are supported, one uses a pulse per second (PPS)
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signal provided by the source clock and the other mode reads time from the
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source clock directly. Some clocks can be used in both modes, the mode which
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will synchronize the slave clock with better accuracy depends on hardware and
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driver implementation.
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will synchronize the slave clock with better accuracy depends on hardware
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and driver implementation.
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.SH OPTIONS
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.TP
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.BI \-a
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Read the clocks to synchronize from running
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.B ptp4l
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and follow changes in the port states, adjusting the synchronization
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direction automatically. The system clock (CLOCK_REALTIME) is not
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synchronized, unless the
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.B \-r
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option is also specified.
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.TP
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.BI \-r
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Only valid together with the
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.B \-a
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option. Instructs
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.B phc2sys
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to also synchronize the system clock (CLOCK_REALTIME). By default, the
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system clock is not considered as a possible time source. If you want the
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system clock to be eligible to become a time source, specify the
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.B \-r
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option twice.
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.TP
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.BI \-d " pps-device"
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Specify the PPS device of the master clock (e.g. /dev/pps0). With this option
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the PPS synchronization mode is used instead of the direct mode. As the PPS
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@ -68,7 +81,10 @@ option the PPS signal of the master clock is enabled automatically, otherwise
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it has to be enabled before
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.B phc2sys
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is started (e.g. by running \f(CWecho 1 > /sys/class/ptp/ptp0/pps_enable\fP).
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This option can be used only with the system clock as the slave clock.
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This option can be used only with the system clock as the slave clock. Not
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compatible with the
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.B \-a
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option.
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.TP
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.BI \-s " device"
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Specify the master clock by device (e.g. /dev/ptp0) or interface (e.g. eth0) or
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@ -76,7 +92,9 @@ by name (e.g. CLOCK_REALTIME for the system clock). When this option is used
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together with the
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.B \-d
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option, the master clock is used only to correct the offset by whole number of
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seconds, which cannot be fixed with PPS alone.
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seconds, which cannot be fixed with PPS alone. Not compatible with the
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.B \-a
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option.
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.TP
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.BI \-i " interface"
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Performs the exact same function as
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@ -89,7 +107,10 @@ should no longer be used.
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.TP
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.BI \-c " device"
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Specify the slave clock by device (e.g. /dev/ptp1) or interface (e.g. eth1) or
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by name. The default is CLOCK_REALTIME (the system clock).
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by name. The default is CLOCK_REALTIME (the system clock). Not compatible
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with the
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.B \-a
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option.
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.TP
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.BI \-E " servo"
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Specify which clock servo should be used. Valid values are pi for a PI
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@ -128,7 +149,10 @@ minimize the error caused by random delays in scheduling and bus utilization.
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The default is 5.
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.TP
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.BI \-O " offset"
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Specify the offset between the slave and master times in seconds. See
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Specify the offset between the slave and master times in seconds. Not
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compatible with the
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.B \-a
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option. See
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.SM
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.B TIME SCALE USAGE
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below.
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@ -154,7 +178,9 @@ Wait until ptp4l is in a synchronized state. If the
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.B \-O
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option is not used, also keep the offset between the slave and master
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times updated according to the currentUtcOffset value obtained from ptp4l and
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the direction of the clock synchronization.
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the direction of the clock synchronization. Not compatible with the
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.B \-a
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option.
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.TP
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.BI \-n " domain-number"
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Specify the domain number used by ptp4l. The default is 0.
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@ -198,6 +224,8 @@ clock follows UTC. Time offset between these two is maintained by
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.B Phc2sys
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acquires the offset value either by reading it from ptp4l when
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.B \-a
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or
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.B \-w
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is in effect or from command line when
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.B \-O
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@ -208,6 +236,21 @@ master.
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.SH EXAMPLES
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Synchronize time automatically according to the current
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.B ptp4l
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state, synchronize the system clock to the remote master.
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.RS
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\f(CWphc2sys \-a \-r\fP
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.RE
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Same as above, but when the host becomes the domain master, synchronize time
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in the domain to its system clock.
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.RS
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\f(CWphc2sys \-a \-rr\fP
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.RE
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The host is a domain master, PTP clock is synchronized to system clock and the
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time offset is obtained from
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.BR ptp4l .
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