CLOCKFLAGS="$CLOCKFLAGS --hctosys"

case "$UTC" in
    yes|true)   CLOCKFLAGS="$CLOCKFLAGS --utc"
                CLOCKDEF="$CLOCKDEF (utc)" ;;
    no|false)   CLOCKFLAGS="$CLOCKFLAGS --localtime"
                CLOCKDEF="$CLOCKDEF (localtime)" ;;
esac
case "$ARC" in
    yes|true)   CLOCKFLAGS="$CLOCKFLAGS --arc"
                CLOCKDEF="$CLOCKDEF (arc)" ;;
esac
case "$SRM" in
    yes|true)   CLOCKFLAGS="$CLOCKFLAGS --srm"
                CLOCKDEF="$CLOCKDEF (srm)" ;;
esac

[ -x /sbin/hwclock ] && /sbin/hwclock $CLOCKFLAGS

struct timespec xtime __attribute__ ((aligned (16)));

#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))
void __init time_init(void)
{
...
//Количество секунд, прошедших с 01.01.1970,
//берется информация из rtc
xtime.tv_sec = get_cmos_time();
//Количество наносекунд, прошедших с начала текущей секунды
//INITIAL_JIFFIES - это изначальное значение jiffies (его делают
"отрицательным")
//!!Это место мне не очень понятно
// cказано, что tv_nsec выбирают таким образом, чтобы первое переполнение jiffies попало на границу секунды, 
//но с таким значение, как выбрано, этого не происходит. Попробую выяснить.
xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
...
}

static struct clocksource *select_clocksource(void)

 * @rating:             rating value for selection (higher is better)
 *                      To avoid rating inflation the following
 *                      list should give you a guide as to how
 *                      to assign your clocksource a rating
 *                      1-99: Unfit for real use
 *                              Only available for bootup and testing purposes.
 *                      100-199: Base level usability.
 *                              Functional for real use, but not desired.
 *                      200-299: Good.
 *                              A correct and usable clocksource.
 *                      300-399: Desired.
 *                              A reasonably fast and accurate clocksource.
 *                      400-499: Perfect
 *                              The ideal clocksource. A must-use where
 *                              available.

/* The Jiffies based clocksource is the lowest common
 * denominator clock source which should function on
 * all systems. It has the same coarse resolution as
 * the timer interrupt frequency HZ and it suffers
 * inaccuracies caused by missed or lost timer
 * interrupts and the inability for the timer
 * interrupt hardware to accuratly tick at the
 * requested HZ value. It is also not reccomended
 * for "tick-less" systems.
 */