Matthias Scheler writes:
> when will the system time be written into the CMOS clock? Only if I halt
> or reboot the system?

Use The Source, Luke!

kern_time.c defines the settimeofday() syscall (and related
friends). These all (indirectly) call resettodr(), which sets the
hardware clock on those machines that possess one.

Thus, simply calling settimeofday from userland will call resettodr().

Perry