NAME¶
atrtc
—
AT Real-Time Clock (RTC) driver
SYNOPSIS¶
This driver is a mandatory part of i386/amd64 kernels.
The following tunable is settable from the
loader(8):
- hint.atrtc.X.clock
- controls event timers functionality support. Setting to 0, disables it.
Default value is 1.
DESCRIPTION¶
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.
SEE ALSO¶
apic(4),
attimer(4),
eventtimers(4),
hpet(4)