On Sun, Oct 17, 2021 at 09:39:23PM +0200, Mateusz Jończyk wrote: > Some Intel chipsets disconnect the time and date RTC registers when the > clock update is in progress: during this time reads may return bogus > values and writes fail silently. This includes the RTC alarm registers. > [1] > > cmos_read_alarm() and cmos_set_alarm() did not take account for that, > which caused alarm time reads to sometimes return bogus values. This can > be shown with a test patch that I am attaching to this patch series. > Setting the alarm clock also probably did fail sometimes. > > To make this patch suitable for inclusion in stable kernels, I'm using a > simple method for avoiding the RTC update cycle. This method is used in > mach_set_rtc_mmss() in arch/x86/kernel/rtc.c. A more elaborate algorithm > - as in mc146818_get_time() in drivers/rtc/rtc-mc146818-lib.c - would be > too complcated for stable. [2] No, just do it properly the first time, do not worry about stable kernels, we can just take the also-correct version for backporting if needed. thanks, greg k-h
