On Mon, Feb 19, 2018 at 08:11:05AM +0100, Rasmus Villemoes wrote: > It's because util-linux's hwclock still assumes the world is x86. See > this comment in the util-linux source code: > > /* > * The Hardware Clock can only be set to any integer time plus one > * half second. The integer time is required because there is no > * interface to set or get a fractional second. The additional half > * second is because the Hardware Clock updates to the following > * second precisely 500 ms (not 1 second!) after you release the > * divider reset (after setting the new time) - see description of > * DV2, DV1, DV0 in Register A in the MC146818A data sheet (and note > > So if hwclock is asked to --systohc at time 01:02:03.x, it waits until > the time is 01:02:03.5 to set the rtc to 01:02:03, or if that has > already passed, waits until 01:02:04.5 and sets it to 01:02:04. > > On our ARM BSP we patch util-linux to have the "implicit fractional > part" configurable, and trying to upstream something like that has been > on my todo-list for quite a while. See > > https://raw.githubusercontent.com/oe-lite/base/master/recipes/util-linux/util-linux-2.29/hwclock-tweak-delay.patch > > for the patch we currently use (on top of that, we change the 0.5 > initializer to 0.0 to avoid having to always pass the --delay argument). > Incidentally, it seems we're on the same util-linux version, so you > should be able to try out that patch and see if it works for you. Would be possible to somehow detect what is the right default setting for --delay? I mean for example detect architecture / clock HW, etc. I have no problem with --delay, but it's tuning for advanced users and HW specific stuff. It would be nice to have something more portable. Karel -- Karel Zak <kzak@xxxxxxxxxx> http://karelzak.blogspot.com -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
