NVRAM stuck in DST?

Benjamin Herrenschmidt benh at kernel.crashing.org
Sat Dec 8 08:38:04 EST 2001

>Hmmm... DST on? That's wrong; we're not in DST anymore! And the current
>offset to GMT is one hour, not two hours. I'm wondering whether
>something else besides MacOS sets those values.

AFAIK, MacOS is the only one to set it.

>If not, then I'll be stuck with whatever NVRAM values MacOS wrote there
>when it was last booted. Which means that unless at every DST time
>change, unless I bot MacOS once, I'll be stuck with the wrong time....

Yup, we need a proper tool for that. Actually, we need 2 things

 - a way for /dev/nvram to let userland know about the partitioning
of the nvram (expecially where the xpram is)
 - then a tool using that to write to the MachineLocation record
in nvram containing the tz offset and DST flag.

>Also, just for my understanding, doesn't MacOS save the system time in
>the RTC in localtime? In that case I don't see how time _advances_ on
>boot... unless the MacOS RTC is in DST-less localtime.

The kernel time is calculated from the RTC local time, offseted by
the pram gmt offset & dst to get a GMT time.


** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

More information about the Linuxppc-dev mailing list