> Rafael Reilova writes:
> > Lastly, the problem we are trying to solve seems to be mostly a non-issue,
> > at least at boot, since hwclock can set the system clock properly before
> > anything important happens. The more interesting problem is the one
> > Richard brought up with APM. I think it goes like this:
> >
> > 1) DST changeover is about to happen
> >
> > 2) the machine goes into APM, before doing so the kernel in apm.c
> > computes a timezone offset to be used when coming out of APM.
> >
> > 3) timezone changeover occurs due to DST going on or off.
> >
> > 4) machine comes out of APM, read CMOS and applies wrong offset, sytem
> > time is now warped.
>
> No, this isn't what is happening. The problem is that some machines
> slow down the RTC measurment to the point where the measurement may be
> inaccurate by several seconds. Once the lid is closed, it's too late
> to do an accurate RTC measurement.
OK understood, but is the above scenario possible? I took a quick look at
apm.c and it seemed to fall for such a situation so I thought that was
what you meant. Happens for posting without checking the old mail...grr
About the slowdown, I guess the situation could be detected by doing two
successive reads and checking if they differ significantly. Now what to
do about it is another matter. Maybe we could use a previously computed
offset calculated last time the system time was changed?
Cheers,
-Rafael
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