On Mon, 9 Jul 2018, Arnd Bergmann wrote:
The most likely explanation I have here is that the RTC was indeed set to an incorrect date, either because of a depleted battery (not unlikely for a ~15 year old box) or because it was previously stored incorrectly.
The PowerMac stores the GMT offset in NVRAM, and this gets used to initialize timezone_offset.
If timezone_offset was negative and now.tv_sec was zero, I think this could store a 1969 date in the RTC:
int update_persistent_clock64(struct timespec64 now) { struct rtc_time tm;
if (!ppc_md.set_rtc_time) return -ENODEV;
rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm);
return ppc_md.set_rtc_time(&tm); }
But maybe now.tv_sec can be shown to be greater than timezone_offset.
Then, what would happen when the timezone in /etc/localtime disagrees with the timezone_offset stored in NVRAM (PRAM)?
Besides that, if the battery went flat, what use is a backtrace? Why not scrap the WARN_ON()?
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