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doc: update for recent changes

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Miroslav Lichvar 2015-09-25 17:30:49 +02:00
parent a4d9cfaaeb
commit b49dcfbef7
3 changed files with 50 additions and 64 deletions
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95
chrony.texi.in
View file

@ -120,8 +120,9 @@ different quirks in its behaviour.
The software is known to work on Linux, FreeBSD, NetBSD, Mac OS X and Solaris.
Closely related systems may work too. Porting the software to other systems
(particularly to those supporting an @code{adjtime} system call) should not be
difficult, however it requires access to such systems to test out the driver.
(particularly to those supporting an @code{adjtime} or @code{ntp_adjtime}
system call) should not be difficult, however it requires access to such
systems to test out the driver.
@c }}}
@c {{{ S:Other programs
@node Other time synchronisation packages
@ -163,9 +164,9 @@ step the time too, but it has to use a different means of adjusting the
clock, which has some
disadvantages.
@item
@code{chronyd} can adjust the rate of the clock on Linux in a larger
range, which allows it to operate even on machines with broken or
unstable clock (e.g. in some virtual machines).
@code{chronyd} can adjust the rate of the clock in a larger range, which
allows it to operate even on machines with broken or unstable clock
(e.g. in some virtual machines).
@end itemize
Things @code{chronyd} can do that @code{ntpd} can't:
@ -961,10 +962,9 @@ used. These histories are created by using the @code{dump} command in
@code{chronyc}, or by setting the @code{dumponexit} directive in the
configuration file. This option is useful if you want to stop and
restart @code{chronyd} briefly for any reason, e.g. to install a new
version. However, it only makes sense on systems where the kernel can
maintain clock compensation whilst not under @code{chronyd's} control.
The only version where this happens so far is Linux. On other systems
this option should not be used.
version. However, it should be used only on systems where the kernel
can maintain clock compensation whilst not under @code{chronyd's}
control (i.e. Linux, FreeBSD, NetBSD and Solaris).
@item -R
When this option is used, the @code{initstepslew} directive and the
@code{makestep} directive used with a positive limit will be ignored.
@ -1460,9 +1460,9 @@ combinelimit <limit>
@c {{{ corrtimeratio
@node corrtimeratio directive
@subsection corrtimeratio
When @code{chronyd} makes a time correction, it controls how quickly
the system clock is slewed (so far only on Linux). This rate
affects the frequency error of the system clock.
When @code{chronyd} is slewing the system clock to correct an offset, the rate
at which it is slewing adds to the frequency error of the clock. On Linux,
FreeBSD, NetBSD and Solaris this rate can be controlled.
The @code{corrtimeratio} directive sets the ratio between the
duration in which the clock is slewed for an average correction
@ -1539,12 +1539,11 @@ driftfile @CHRONYVARDIR@/drift
To compute the rate of gain or loss of time, @code{chronyd} has to store
a measurement history for each of the time sources it uses.
Certain systems (so far only Linux) have operating system support for
setting the rate of gain or loss to compensate for known errors. (On
other systems, @code{chronyd} must simulate such a capability by
periodically slewing the system clock forwards or backwards by a
suitable amount to compensate for the error built up since the previous
slew).
Certain systems (Linux, FreeBSD, NetBSD, Solaris) have operating system
support for setting the rate of gain or loss to compensate for known errors.
(On Mac OS X, @code{chronyd} must simulate such a capability by periodically
slewing the system clock forwards or backwards by a suitable amount to
compensate for the error built up since the previous slew).
For such systems, it is possible to save the measurement history across
restarts of @code{chronyd} (assuming no changes are made to the system
@ -1756,8 +1755,8 @@ selects how that error is corrected. There are four options:
When inserting a leap second, the kernel steps the system clock backwards by
one second when the clock gets to 00:00:00 UTC. When deleting a leap second,
it steps forward by one second when the clock gets to 23:59:59 UTC. This is
the default mode when the system driver supports leap seconds (currently Linux
only).
the default mode when the system driver supports leap seconds (i.e. on
Linux, FreeBSD, NetBSD and Solaris).
@item step
This is similar to the @code{system} mode, except the clock is stepped by
@code{chronyd} instead of the kernel. It can be useful to avoid bugs in the
@ -2427,10 +2426,16 @@ maxsamples <samples>
The @code{maxslewrate} directive sets the maximum rate at which @code{chronyd}
is allowed to slew the time. It limits the slew rate controlled by the
correction time ratio (@pxref{corrtimeratio directive}) and is effective
only on systems where @code{chronyd} is able to control the rate (so
far only Linux).
only on systems where @code{chronyd} is able to control the rate (i.e.
Linux, FreeBSD, NetBSD, Solaris).
By default, the maximum slew rate is 83333.333 ppm (one twelfth).
For each system there is a maximum frequency offset of the clock that
can be set by the driver. On Linux it's 100000 ppm, on FreeBSD and NetBSD
it's 5000 ppm and on Solaris it is 32500 ppm. Also, due to a kernel
limitation, setting @code{maxslewrate} on FreeBSD and NetBSD to a value between
500 ppm and 5000 ppm will effectively set it to 500 ppm.
By default, the maximum slew rate is set to 83333.333 ppm (one twelfth).
The syntax is
@ -2851,7 +2856,7 @@ system time is copied to the real time clock (RTC) every 11 minutes.
This directive is supported only on Linux and cannot be used when the
normal RTC tracking is enabled, i.e. when the @code{rtcfile} directive
is used.
is used. On other systems this directive does nothing.
@c }}}
@c {{{ sched_priority
@node sched_priority directive
@ -3323,11 +3328,11 @@ interface.
* allow command:: Allowing NTP client access
* burst command:: Initiating a rapid set of measurements
* clients command:: Show clients that have accessed the server
* cmdaccheck command:: Verifying command client access
* cmdallow all command:: Allowing command client access
* cmdallow command:: Allowing command client access
* cmddeny all command:: Denying command client access
* cmddeny command:: Denying command client access
* cmdaccheck command:: Verifying monitoring client access
* cmdallow all command:: Allowing monitoring client access
* cmdallow command:: Allowing monitoring client access
* cmddeny all command:: Denying monitoring client access
* cmddeny command:: Denying monitoring client access
* cyclelogs command:: Close and re-open open log files
* delete command:: Remove an NTP server or peer
* deny all command:: Denying NTP client access
@ -3621,7 +3626,7 @@ of that type has ever been received.
@node cmdaccheck command
@subsubsection cmdaccheck
This command is similar to the @code{accheck} command, except that it is
used to check whether command access is permitted from a named host.
used to check whether monitoring access is permitted from a named host.
Examples of use are as follows:
@ -3634,30 +3639,30 @@ cmdaccheck 2001:db8::1
@c {{{ cmdallow all
@node cmdallow all command
@subsubsection cmdallow all
This is similar to the @code{allow all} command, except that it is used to@c {{{
allow particular hosts or subnets to use the chronyc program to interact@c }}}
with @code{chronyd} on the current host.
This is similar to the @code{allow all} command, except that it is used to
allow particular hosts or subnets to use @code{chronyc} to monitor with
@code{chronyd} on the current host.
@c }}}
@c {{{ cmdallow
@node cmdallow command
@subsubsection cmdallow
This is similar to the @code{allow} command, except that it is used to
allow particular hosts or subnets to use the chronyc program to interact
with @code{chronyd} on the current host.
This is similar to the @code{allow} command, except that it is used to allow
particular hosts or subnets to use @code{chronyc} to monitor with
@code{chronyd} on the current host.
@c }}}
@c {{{ cmddeny all
@node cmddeny all command
@subsubsection cmddeny all
This is similar to the @code{deny all} command, except that it is used
to allow particular hosts or subnets to use the chronyc program to
interact with @code{chronyd} on the current host.
This is similar to the @code{deny all} command, except that it is used to allow
particular hosts or subnets to use @code{chronyc} to monitor @code{chronyd} on
the current host.
@c }}}
@c {{{ cmddeny
@node cmddeny command
@subsubsection cmddeny
This is similar to the @code{deny} command, except that it is used to
allow particular hosts or subnets to use the chronyc program to interact
with @code{chronyd} on the current host.
This is similar to the @code{deny} command, except that it is used to allow
particular hosts or subnets to use @code{chronyc} to monitor @code{chronyd} on
the current host.
@c }}}
@c {{{ cyclelogs
@node cyclelogs command
@ -4571,12 +4576,6 @@ true time (which it reports to NTP clients when it is operating in
server mode). The value reported on this line is the difference due to
this effect.
On systems other than Linux, @code{chronyd} doesn't
adjust the fundamental rate of the system clock, so keeps the system
time correct by periodically making offsets to it as though an error had
been measured. The build up of these offsets will be observed in this
report.
@item Last offset
This is the estimated local offset on the last clock update.

5
chronyd.8.in
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@ -69,10 +69,9 @@ This option will reload sample histories for each of the servers being used.
These histories are created by using the \fIdump\fR command in \fIchronyc\fR,
or by setting the \fIdumponexit\fR directive in the configuration file. This
option is useful if you want to stop and restart \fBchronyd\fR briefly for any
reason, e.g. to install a new version. However, it only makes sense on
reason, e.g. to install a new version. However, it should be used only on
systems where the kernel can maintain clock compensation whilst not under
\fBchronyd\fR's control. The only version where this happens so far is Linux.
On other systems this option should not be used.
\fBchronyd\fR's control (i.e. Linux, FreeBSD, NetBSD and Solaris).
.TP
.B \-R
When this option is used, the \fIinitstepslew\fR directive and the

14
doc/faq.adoc
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@ -20,7 +20,7 @@ http://chrony.tuxfamily.org/manual.html#Comparison-with-ntpd[Comparison with
ntpd] section in the manual.
If your computer is connected to the internet only for few minutes at a time,
the network connection is often congested, you turn your Linux computer off or
the network connection is often congested, you turn your computer off or
suspend it frequently, the clock is not very stable (e.g. there are rapid
changes in the temperature or it's a virtual machine), or you want to use NTP
on an isolated network with no hardware reference clocks in sight, +chrony+
@ -324,18 +324,6 @@ be useful to switch the servers to the offline state automatically.
Some other program running on the system may be using the device.
== Solaris-specific issues
=== I get an error message about not being able to open kvm to change dosynctodr
(The dosynctodr variable controls whether Solaris couples the equivalent
of its BIOS clock into its system clock at regular intervals). The
Solaris port of +chrony+ was developed in the Solaris 2.5 era. Some
aspect of the Solaris kernel has changed which prevents the same
technique working. We no longer have root access to any Solaris
machines to work on this, and we are reliant on somebody developing the
patch and testing it.
== Microsoft Windows
=== Does +chrony+ support Windows?