>Since the clock is not changed for DST only a reference to a table offset
>from GMT, why would the clock change by two hours? The clock should not
>change just a -4 going to -5 from GMT for EST. I don't understand how dual
>boot would affect this?

>Please help me to understand.

The Solaris/Unix system clock runs in "GMT", that much is true.

Unfortunately, once upon a long ago, when the PC was first thrown together
and DOS was written, the system clock (hardware clock) was defined as 
running in "wall clock" or local time.

When the system boots, it reads /etc/rtc_config which contains the current
offset from real time and the timezone.

Now, when DST changes the "localtime" must change but Solaris really has no
idea that that happens.  What does happen is that the /etc/rtc_config gets
out of sync (but combined local time + remembered offset return the proper
GMT time)

In root's cron we run the "rtc" command; this verifies whether the offset
and the localtime are still correct.  When they are not correct it adjust
both offset in /etc/rtc_config *AND* the hardware's idea of the time.

The system's clock gets changed and this changed is noted in /etc/
rtc_config.

But because the fact that the time change took place is recorded in the
system's own boot record, each system will affect its own change, be it 
windows, Solaris, multiple Solaris images, etc.

I run Solaris in "GMT" and attempt to do the same with Windows (works as 
long as you do not hibernate, see a blog entry I wrote about this)

I'm not sure what happens now if /etc/rtc_config is out of sync in the
boot-archive.


How it can happen if you only boot one OS image is beyond me, though.

Casper

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