On 03/12/2020 11:52:49-0400, Jason Gunthorpe wrote: > On Thu, Dec 03, 2020 at 03:10:47AM +0100, Alexandre Belloni wrote: > > > IIRC, used in conjunction with rtc_hctosys which also adds > > inconditionnaly 500ms this can ends up with the system time > > being one second away from the wall clock time which NTP will take quite > > some time to remove. > > I can't remember the details, but this was not the intention. > > As long as systohc and hctosys exist then the design goal of rtclib > should be to provide sub-second accuracy on the round trip of time > through the RTC. > > Otherwise what is the point? > hctosys never had a sub second accuracy because there is no way to accurately read the rtc time without being ready to wait up to a second. I have patches doing exactly that but I'm pretty sure nobody wants to pay the price and have a kernel that boots significantly slower. Especially since that would basically affect everyone since systemd requires that hctosys is enabled. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
