Very Computer

Hi all,

In understand that Linux does not have a Y2K problem in the same sense
as a lot of DOS/Windows applications will.

What I am wondering about is the Real Time Clock issues. As I
understand it (and please correct me if I'm wrong):

* Computer starts up
* BIOS sets RTC
* Linux gets time from BIOS

IE - if the computer doesn't rollover while powered off simply
changing the date after booting up post-2000 will cure the problem.

However what happens when Linux is shutdown? It has been maintaining
the time itself internally, does this get written back to the BIOS
and/or RTC? Is this distribution dependant (I suspect so)? Are any
distributions broken in this respect?

A problem I can forsee is systems which simply run until they crash -
if the system runs over the Y2K boundary, then crashes sometime in the
new year, will the date than most likely by in the 1900/1980 range,
because of the RTC problems?

My guess is that all Linux systems should run something like:

    clock -w

as soon as possible after the turn of the century.

Does anyone else have any thoughts/experience on this matter?

Thanks.

        - Justin

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On 24 Nov 1998 15:29:39 +1030,

Quote:> In understand that Linux does not have a Y2K problem in the same sense
> as a lot of DOS/Windows applications will.

True.

Quote:> What I am wondering about is the Real Time Clock issues. As I
> understand it (and please correct me if I'm wrong):

> * Computer starts up
> * BIOS sets RTC
> * Linux gets time from BIOS

> IE - if the computer doesn't rollover while powered off simply
> changing the date after booting up post-2000 will cure the problem.

Not quite: the RTC is a chip.  Linux doesn't care what the BIOS thinks
the day/time is, it just asks the clock chip itself.

Quote:> However what happens when Linux is shutdown? It has been maintaining
> the time itself internally, does this get written back to the BIOS
> and/or RTC? Is this distribution dependant (I suspect so)? Are any
> distributions broken in this respect?

Yep, the kernel automatically does that... if your clock is synchronized
with NTP.   (It's set every 11 minutes or so.)

Quote:> A problem I can forsee is systems which simply run until they crash -
> if the system runs over the Y2K boundary, then crashes sometime in the
> new year, will the date than most likely by in the 1900/1980 range,
> because of the RTC problems?

Probably 1900: but then, that won't be a problem either, since the
kernel will map that to 2000 on reboot.  (And if running NTP, will of
course reprogram the clock chip 11 minutes later.)

Quote:> My guess is that all Linux systems should run something like:

>     clock -w

> as soon as possible after the turn of the century.

Can't hurt, but then NTP is your friend.

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