The Tuesday 2004-05-04 at 22:43 +0200, Anders Johansson wrote:
No, it is not accessed at all, for many reasons. One, it is a very slow access. Two, the CPU maintains its own clock, and doesn't need it.
/usr/src/linux/arch/i386/kernel/time.c
do_timer_interrupt()
It is accessed, around once every 11 minutes it seems, though I'm not entirely certain under what circumstances STA_UNSYNC is set, I didn't trace it that deeply.
Huh? Ah, Well; it can be periodically updated, on certain circumstances: /* * If we have an externally synchronized Linux clock, then update * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be * called as close as possible to 500 ms before the new second starts. */ That may be of use when the kernel got synchronized by ntpd, for example.
In any case, /dev/rtc has many uses in a running system, even if not by the kernel itself
Of course it has :-)
Read my howto, it is documented there, and my sources for so saying.
I only read one source.
I never read only one source for any writeup :-)
And some (or all) of those chips are also powered from the board 5 Vcc while powered up.
OK, that is interesting. Then maybe this debate is entirely pointless :)
-- Cheers, Carlos Robinson