On Tue, Aug 01, 2017 at 09:20:59AM -0400, J William Piggott wrote:
>
> Add information about setting the Hardware Clock if it has been
> corrupted.
>
> Add information about --update-drift and reduced system shutdown
> times for --systohc.
Ok :-)
Karel
>
> Signed-off-by: J William Piggott <elseifthen@xxxxxxx>
> ---
> sys-utils/hwclock.8.in | 26 ++++++++++++++++++++------
> 1 file changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/sys-utils/hwclock.8.in b/sys-utils/hwclock.8.in
> index e0862c9..107e3f1 100644
> --- a/sys-utils/hwclock.8.in
> +++ b/sys-utils/hwclock.8.in
> @@ -4,7 +4,7 @@
> .\" Authored new section: DATE-TIME CONFIGURATION.
> .\" Subsections: Keeping Time..., LOCAL vs UTC, POSIX vs 'RIGHT'.
> .\"
> -.TH HWCLOCK 8 "April 2015" "util-linux" "System Administration"
> +.TH HWCLOCK 8 "July 2017" "util-linux" "System Administration"
> .SH NAME
> hwclock \- time clocks utility
> .SH SYNOPSIS
> @@ -197,8 +197,9 @@ Set the Hardware Clock to the time given by the
> option, and update the timestamps in
> .IR @ADJTIME_PATH@ .
> With the
> -.B --update-drift
> -option (re)calculate the drift factor.
> +.B \%\-\-update-drift
> +option also (re)calculate the drift factor. Try it without the option if
> +.BR \%\-\-set " fails. See " \%\-\-update-drift " below."
> .
> .TP
> .B \-\-systz
> @@ -234,9 +235,10 @@ changed then a reboot would be required to inform the kernel.
> .BR \-w , \ \-\-systohc
> Set the Hardware Clock from the System Clock, and update the timestamps in
> .IR @ADJTIME_PATH@ .
> -When the
> -.B --update-drift
> -option is given, then also (re)calculate the drift factor.
> +With the
> +.B \%\-\-update-drift
> +option also (re)calculate the drift factor. Try it without the option if
> +.BR \%\-\-systohc " fails. See " \%\-\-update-drift " below."
> .
> .TP
> .BR \-V , \ \-\-version
> @@ -404,6 +406,11 @@ on the drift factor.
> (Re)calculating drift factor on every shutdown delivers suboptimal
> results. For example, if ephemeral conditions cause the machine to be
> abnormally hot the drift factor calculation would be out of range.
> +.IP \(bu 2
> +Significantly increased system shutdown times (as of v2.31 when not
> +using
> +.B \%\-\-update\-drift
> +the RTC is not read).
> .PP
> .RB "Having " \%hwclock
> calculate the drift factor is a good starting point, but for optimal
> @@ -414,6 +421,13 @@ crafted it should not need to be changed. Therefore, the old behavior to
> automatically (re)calculate drift was changed and now requires this
> option to be used. See the discussion below, under
> .BR "The Adjust Function" .
> +.PP
> +This option requires reading the Hardware Clock before setting it. If
> +it cannot be read, then this option will cause the set functions to fail.
> +This can happen, for example, if the Hardware Clock is corrupted by a
> +power failure. In that case, the clock must first be set without this
> +option. Despite it not working, the resulting drift correction factor
> +would be invalid anyway.
> .RE
> .
> .SH NOTES
> --
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--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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