Fix RTC_Linux_TimePreInit() to return 0 when the RTC device can be
opened, but reading its time fails to at least have the time restored
from the driftfile.
Add a new change type and use it when an unexpected time jump is
detected in the scheduler to reset reference times, offset and slewing,
NCR instances (with their polling interval), synchronization status, and
drop all sourcestats, manual, refclock and RTC samples.
This should make the recovery more graceful if the estimated jump has a
large error (e.g. select didn't timeout, or after system suspend).
When chrony reads in the linux rtc for the first time to trim the system
clock, it only reads it once. As it is possible that the rtc updates
itself during the read operation, the reported rtc time could be false.
To prevent this I've added a loop that reads the rtc clock twice, if the
seconds do not match retry the two read operations. If they match you
can assume the read operation was successful.
This is based on the hwclock implementation of reading the rtc clock
from the util-linux package.
This is a revert of commit 99d18abf updated for later changes. It seems
in that commit the calculation was changed to match the reversed dfreq
added in 1a7415a6, which itself was calculated incorrectly. Fix the
calculation of updated frequency and matching dfreq.
The Clang static analyzer scan-build from Debian clang version 3.4-1
found the following unneeded assignment.
rtc_linux.c:756:5: warning: Value stored to 'error' is never read
error = 1;
^ ~
Indeed, if in that if branch, the function returns without ever looking
at the variable `error`. So remove the line.
We want to correct the offset quickly, but we also want to keep the
frequency error caused by the correction itself low.
Define correction rate as the area of the region bounded by the graph of
offset corrected in time. Set the rate so that the time needed to correct
an offset equal to the current sourcestats stddev will be equal to the
update interval (assuming linear adjustment). The offset and the
time needed to make the correction are inversely proportional.
This is only a suggestion and it's up to the system driver how the
adjustment will be executed.
None of the current handlers really need it and with temperature
compensation enabled it would be necessary to undo the compensation
before passing it to the handlers.
