1. 根目录:
2. kernel
3. time
4. Makefile

obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o
obj-y += timeconv.o posix-clock.o alarmtimer.o

obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD)		+= clockevents.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS)		+= tick-common.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)	+= tick-broadcast.o
obj-$(CONFIG_GENERIC_SCHED_CLOCK)		+= sched_clock.o
obj-$(CONFIG_TICK_ONESHOT)			+= tick-oneshot.o
obj-$(CONFIG_TICK_ONESHOT)			+= tick-sched.o
obj-$(CONFIG_TIMER_STATS)			+= timer_stats.o
obj-$(CONFIG_DEBUG_FS)				+= timekeeping_debug.o