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Given "System clock uses UTC" disabled. It would appear that Apple keeps the hwclock in local standard time. even during summer. The system clock being adjusted by an hr during summer. GNU/Linux, on the other hand, appears to think that the hwclock should always exactly match local time. During summer this puts GNU/Linux and Apple one hr out.
Apple stores the UTC delta in XPRAM, and I believe the kernel's RTC driver automatically compensates for it -- thus you should be telling userspace that the system clock _does_ use UTC. Can you show the output of 'dmesg | grep GMT'?
Many reboots later (this really scrambles the clock): System clock uses UTC disabled: Apple==21:xx; Linux=20:xx System clock uses UTC enabled: Apple=21:xxx; linux=16:xx GMT Delta read from XPRAM: -300 minutes, DST: off
Guys, I really don't think this is a s-c-date problem, can you please change it to something more appropriate (don't ask me what is more appropriate -- I would have changed it by myself if I knew).
I can't fix this in system-config-date, I think this can only be fixed in util-linux (hwclock) or the kernel. Pick which one you like best ;-).