On 7 Oct 2022, at 00:24, Steffen Nurpmeso via tz <tz@iana.org> wrote:
But only to throw in that for most systems which are not always-on, and even for some which are, this is rather hypothetic since hardware clocks that i know drift (and Linux hwclock(8) documents "The Hardware Clock is usually not very accurate. However, much of its inaccuracy is completely predictable - it gains or loses the same amount of time every day. This is called systematic drift.")
The clock described by hwclock(8) is not the system clock, it's the RTC for Linux/Unix it's only used to set the initial system time on boot. The system clock is the one that has a predictable drift (eg 7ppm on this machine here). The RTC is basically a 2¢ chip and every bit as accurate as you'd expect; my wind-up watch is more accurate. jch