Provided by: freebsd-manpages_10.1~RC1-1_all bug


     atrtc — AT Real-Time Clock (RTC) driver


     This driver is a mandatory part of i386/amd64 kernels.

     The following tunable is settable from the loader(8):

     controls event timers functionality support. Setting to 0, disables it.  Default value is 1.


     This driver uses RTC hardware to supply kernel with time-of-day clock with 1 second
     resolution and one event timer.  This hardware uses base frequency of 32768Hz for advancing
     time-of-day clock and generating periodic interrupts.  Interrupts could be generated with
     fixed number of frequencies, from 2Hz to 8192Hz, obtained by dividing base frequency by one
     of supported power-of-2 divisors.

     Event timer provided by the driver is irrelevant to CPU power states.


     apic(4), attimer(4), eventtimers(4), hpet(4)