Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r265201

Fix a 2038 bug.

If time_t is 64-bit (i.e. isn't 32-bit) allow any value of year, not
just years less than 2038.

Don't bother fixing the underflow in the case of years before 1903.

MFC after: 1 week
Sponsored by: DARPA, AFRL

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Improve style and wording of comments and sysctl descriptions [1].

Move machdep.ct_debug to debug.clocktime as there was no reason to
actually put it under machdep in r216340.

Submitted by: bde [1]
MFC after: 3 days

Don't tie ct_debug to bootverbose. Provide a sysctl to turn it on or off.
Switch the default to always off.

Reviewed by: kib

Fix some more style(9) issues.

Fix style(9) issues from r215281 and r215282.

MFC after: 1 week

Add some descriptions to sys/kern sysctls.

PR: kern/148710
Tested by: Chip Camden <sterling at camdensoftware.com>
MFC after: 1 week

Fix an XXX comment by answering 'no'. OS X does not set the day-of-week
counter on SMU-based systems, which causes FreeBSD to reject the RTC time
when used in a dual-boot environment. Since we don't use the day-of-week
counter anyway, solve this by just not checking that it matches.

MFC after: 3 weeks

Now that all platforms use genclock, shuffle things around slightly
for better structure.

Much of this is related to <sys/clock.h>, which should really have
been called <sys/calendar.h>, but unless and until we need the name,
the repocopy can wait.

In general the kernel does not know about minutes, hours, days,
timezones, daylight savings time, leap-years and such. All that
is theoretically a matter for userland only.

Parts of kernel code does however care: badly designed filesystems
store timestamps in local time and RTC chips almost universally
track time in a YY-MM-DD HH:MM:SS format, and sometimes in local
timezone instead of UTC. For this we have <sys/clock.h>

<sys/time.h> on the other hand, deals with time_t, timeval, timespec
and so on. These know only seconds and fractions thereof.

Move inittodr() and resettodr() prototypes to <sys/time.h>.
Retain the names as it is one of the few surviving PDP/VAX references.

Move startrtclock() to <machine/clock.h> on relevant platforms, it
is a MD call between machdep.c/clock.c. Remove references to it
elsewhere.

Remove a lot of unnecessary <sys/clock.h> includes.

Move the machdep.disable_rtc_set sysctl to subr_rtc.c where it belongs.
XXX: should be kern.disable_rtc_set really, it's not MD.

fix printf type confusion on amd64

Emit summaries of struct c(alender)t(ime) <-> struct timespec conversions
under bootverbose.

Struct ct is used for setting/reading real time clocks and I'm about
to Do Things to some of those, so a bit of preemptive debugging is
in order.

Remove a pointless __inline.

If clock_ct_to_ts fails to convert time time from the real time clock,
print a one line error message. Add some comments on not being able to
trust the day of week field (I'll act on these comments in a follow up
commit).

Approved by: re
MFC after: 3 weeks

Use utc_offset() where applicable, and hide the internals of it
as static variables.

Introduce utc_offset() to capture a calculation currently done all over the
place.

Move tz_minuteswest and tz_dsttime to subr_clock.c

Second part of a little cleanup in the calendar/timezone/RTC handling.

Split subr_clock.c in two parts (by repo-copy):
subr_clock.c contains generic RTC and calendaric stuff. etc.
subr_rtc.c contains the newbus'ified RTC interface.

Centralize the machdep.{adjkerntz,disable_rtc_set,wall_cmos_clock}
sysctls and associated variables into subr_clock.c. They are
not machine dependent and we have generic code that relies on being
present so they are not even optional.

Remove more straggling CPU_ macro references

/* -> /*- for copyright notices, minor format tweaks as necessary

Remove advertising clause from University of California Regent's license,
per letter dated July 22, 1999.

Approved by: core

Use __FBSDID().

Split the global timezone structure into two integer fields to
prevent the compiler from optimizing assignments into byte-copy
operations which might make access to the individual fields non-atomic.

Use the individual fields throughout, and don't bother locking them with
Giant: it is no longer needed.

Inspired by: tjr

Use the CPU_* OID constants instead of OID_AUTO for the clock-related
sysctls for compatability with old applications.

Add a generic implementation of inittodr() and resettodr(), as well as
a set of helper routines to deal with real-time clocks. The generic
functions access the clock diver using a kobj interface. This is intended
to reduce code reduplication and make it easy to support more than one
clock model on a single architecture.

This code is currently only used on sparc64, but it is planned to convert
the code of the other architectures to it later.