[time-nuts] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
David J Taylor
david-taylor at blueyonder.co.uk
Sat Nov 3 09:18:52 UTC 2012
-----Original Message-----
From: Sarah White
[]
Seeing as I'm in the process of installing a hardware refclock (trimble
thunderbolt connected via serial port) for my NTP, it is highly
problematic and potentially error-prone for microsoft's OS to touch the
bios hardware clock AT ALL.
I'm entertaining the notion of writing a kernel-mode hardware timestamp
/ PPSAPI driver to pull the signal off the 1 PPS port on the tbolt one
way or another.
I plan to do this on windows. This is something I want to attempt even
though the NT kernel doesn't have the best reputation for realtime
hardware / interrupt handling. Plan is to put in a non-zero amount of
work, up to and including steps where I go through the driver signing
run-around with microsoft to actually have it fully recognized by the OS
without modification. (unless budget issues are a limiting factor)
[]
========================================
Sarah,
I don't know which version of Windows you are proposing to use, but I have
NTP stratum-1 servers based on GPS devices with a PPS signal on the DCD line
of the COM port, and Windows altering, or not altering, the hardware clock
has /no effect/ at all. I'm using Dave Hart's serialPPS.sys device driver
on Windows-2000 up to Windows-7/64 (including telling Win-7/64 to ignore the
signed 64-bit driver requirement).
GPS hardware:
http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm
http://www.satsignal.eu/ntp/Sure-GPS.htm
Windows stratum-1 notes:
http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html
I would note that for the best performance on a stratum-1 server you may
want to try FreeBSD or even Linux on a Raspberry Pi.
http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html
If Dave Hart's driver suits your needs, I'm sure he would be interested in
getting it signed for Microsoft use (if he hasn't already done so).
Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
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