On Fri, Oct 21, 2016 at 08:09:38AM -0500, Richard Owlett wrote:
I'm creating a preseed.cfg file for installing Debian 8.6 in a
dual-boot enviroment with some version of MS Windows. There are two
distinct use cases:
1. Two of my machines with WinXP Pro SP3
2. A remote (~1000 miles]friend with several machines - some with
WinXP, others with
Windows 10 or later.
I have discovered on my WinXP machine that:
1. WinXP _displays_ the correct time.
"Date and Time Properties" - Time Zone set to
(GMT-06:00)Central Time(US&Canada)
Automatically adjust clock for daylight saving changes
2. Debian 8.6 w MATE run from LIVE DVD _displays_ the correct time
3. Debian 8.6 w MATE installed from DVD 1 of 13 with aid of custom
preseed.cfg
_displays_ a time 5 hours earlier.
The _display_ is independent of whether
d-i clock-setup/utc boolean true
*OR*
d-i clock-setup/utc boolean false
is used in the preseed.cfg file.
I'm confused.
If you're not using NTP to provide your time, then, at boot, the
operating system will query the "hardware clock" to see what time it is.
As the hardware clock can drift, operating systems will also set the
hardware clock to match the "system clock" at shutdown time (the system
clock is the time that the operating system is using).
The problem comes that there is no way for the hardware clock (HWClock)
to report what timezone it was set to. There are basically two options
here:
1. The HWClock is set to "Local Time". In this case, the operating
system sees "12:23" as being "12:23 GMT" or "12:23 CST" or whatever and
attempts no translation of the clock.
2. The HWClock is set to "Universal Time" (which is a non-geographical
datum time zone, with no daylight changes). In this case, the operating
system sees "12:23" as ONLY being "12:23 UTC" and translates that into
the local time zone by adding or subtracting hours appropriately.
If you only have one operating system on your machine, either of these
methods is fine. If you have TWO (or more) operating systems, though,
then they SHOULD agree on what the time in the HWClock represents. If
Windows thinks it's local time, but Debian thinks it's UTC, then you'll
see five-hour shifts each time you boot.
You've already found the setting in Debian, I see, so you probably want
to check it tallies with what Windows is using. For that, look at the
Registry Key
HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal.
If this is 1, then the HWClock is using UTC; if it is 0, then the
HWClock is set to local time.
Hopefully that helps.
--
For more information, please reread.
