I have a very unusual issue with the Daylight Savings Time operation of the RTC in the ICH8.
On April 2, 2017 at 2 am, several boards using Intel chipset ICH8 jumped 1 hour ahead.
We could not reproduce in the lab at first, but after several attempts, it did occur, then kept occurring every time we ran past 2am on 4/2/2017.
We found there was a bug in our software that was always setting Bit 0 (DSE) of register B of the RTC.
Turning this bit off disables the DST shift on the units that it was occurring.
Now, the question is: why did it not happen on all units? Is there something else that would prevent DST when it is enabled?
And, why does it only do the "spring ahead" and not the "fall back" adjustment?
To get even weirder, the same bug that always enabled DST was also in an older product with intel 486 and MC146818. Even though DST was always enabled, it never did DST adjustments (not on 1st or last Sunday in April or any other date tested). Is there something else that disables DST even though Reg B of the 146818 enables it?