Currently, the following four sysctl variables reside in the 'machdep' namespace for historical reasons: machdep.disable_rtc_set machdep.wall_cmos_clock machdep.adjkerntz machdep.rtc_save_period They should be moved to the 'kern' namespace for cleanliness. Comment found in /sys/kern/subr_clock.c: /* * The adjkerntz and wall_cmos_clock sysctls are in the "machdep" sysctl * namespace because they were misplaced there originally. */ Comment found in /sys/kern/subr_rtc.c: /* XXX: should be kern. now, it's no longer machdep. */