This is useful on computers that have an RTC, but there is no battery to
keep the time when they are turned off and start with the same time on
each boot.
Instead of calling the handler directly schedule a timeout with zero
delay for resolving to make the function behave similarly to the real
asynchronous resolver. This should prevent problems with code that
inadvertently depends on this behavior and which would break only when
compiled without support for asynchronous resolving.
The system drivers may implement their own slewing which the generic
driver can use to slew faster than the maximum frequency the driver is
allowed to set directly.
Remove driver functions based on adjtime() and switch to the new timex
driver. The kernel allows the timex frequency to be set in the full
range of int32_t, which gives a maximum frequency of 32768 ppm. Round
the limit to 32500 ppm.
- a feature test macro is needed to get msg_control in struct msghdr
- variables must not be named sun to avoid conflict with a macro
- res_init() needs -lresolv
- configure tests for IPv6 and getaddrinfo need -lsocket -lnsl
- pid_t is defined as long and needs to be cast for %d format
Check if the C compiler works to get a useful error message when it
doesn't or it's missing. If the CC environment variable is not set, try
gcc and then cc.
Switch from the SunOS adjtime() based driver to the timex driver.
There is no FreeBSD-specific code, so call SYS_Timex_Initialise()
and SYS_Timex_Finalise() directly from sys.c.
Remove the driver functions based on adjtime() and switch to the new
timex driver, which is based on ntp_adjtime(). This allows chronyd to
control the kernel frequency, adjust the offset with sub-microsecond
accuracy, and set the kernel leap and sync status. A drawback is that
the maximum slew rate is now limited by the 500 ppm maximum frequency
offset, while adjtime() on NetBSD slewed by up to 5000 ppm.
Remove functions that are included in the new timex driver. Keep only
functions that have extended functionality, i.e. read and set the
frequency using the timex tick field and apply step offset with
ADJ_SETOFFSET.
Merge the code from wrap_adjtimex.c that is still needed with
sys_linux.c and remove the file.
This is based on sys_linux.c and wrap_adjtimex.c. It's intended for all
systems that support the adjtimex() or ntp_adjtime() system call. The
driver functions can be replaced with extended system-specific versions
(e.g. to control the frequency with the tick field on Linux).
Include a test program to determine how the adjtime() implementation
behaves. Check the range of supported offset, support for readonly
operation, and slew rate with different update intervals and offsets.
Also, add a test for ntp_adjtime() to check what frequency range it
supports.
