Correct the 6 second offset issue between the time reported by
dmesg -T and the actual time a message was produced, noted on
current-users by Geoff Wing (Oct 27, 2018).

The size of the offset would depend upon architecture, and processor,
but was the delay from starting the clocks to initialising the time
of day (after mounting root, in case that is needed).

Change the kernel to set boottime to be the time at which the
clocks were started, rather than the time at which it is init'd
(by subtracting the interval between).

Correct dmesg to properly compute the ToD based upon the
boottime (which is a timespec, not a timeval, and has been
since Jan 2009) and the time logged in the message.

Note that this can (rarely) be 1 second earlier than date reports.
This occurs when the time when the message was logged was actually
in the next second, but the timecounters have not yet processed
the tick, and so the time of the last tick, near the end of the
previous second, is reported instead. Since times are always
truncated, rather than rounded, it is occasionally possible to
observe that disparity (if you try hard enough).

IOW: sys/kern/subr_prf.c:addtstamp() uses getnanouptime() rather
than nanouptime().

Note in dmesg(8) that -T conversions are gibberish other than
when the message comes from current the running kernel. (It
could be fixed when -M is used, for messages generated by the
kernel whose corpse is being observed. But hasn't been...)

s/or/of/ (a common typo of mine) and s/or// (too many of them.)

Remove a comma and some trailing whitespace.

changes from kre@
- pass intmax to fmtydhmsf instead of time_t to avoid extra conversions.
- make -TTT mean "always keep 3 decimal digits of duration precision" (ie:
always print ms) (including trailing 0's, even .000 if it happens)
- make -T (all forms) be subject to the locale (obey the radix character)
- don't print ymd, since that would require calendar calculations to get
right.

add -TT printing ISO 8601 duration

branches: 1.21.2;

Minor wording change (no date bump needed.)

Sort flags in SYNOPSIS.

match the linux dmesg flags.

Handle new timestamp sequences.

branches: 1.17.12;
dmesg first appeared in 3BSD
http://minnie.tuhs.org/cgi-bin/utree.pl?file=3BSD/usr/src/cmd/dmesg.c
Bump date.

Bump date for previous; add comma in SEE ALSO; use Dv instead of Em.

Talk a little about the system message buffer and cross-reference
MSGBUFSIZE in options(4).

branches: 1.14.2;
Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22308, verified by myself.

branches: 1.13.2;
Drop arguments of .Os.

branches: 1.12.2;
The default core file is /dev/mem, not /dev/kmem.

branches: 1.11.2;
Mention /var/run/dmesg.boot

branches: 1.10.4;
- cleanup for WARNS=1
- cleanup .Nm usage

convert to new RCS Id conventions; reduce my headache

vmunix -> netbsd (PR #375)

branches: 1.7.2;
clean up import

Add RCS indentifiers.

Add FILES section.

Update file names.

changed "Id" to "Header" for rcsids

added rcs ids to all files

branches: 1.1.1;
Initial revision