[Pool] High Offset / Jitter
alby at empire.org
Tue Mar 1 19:11:48 UTC 2011
You are my heroine today. :) Looks like I gotta get crack'n on
upgrading debian to squeeze and 2.6.37 :)
On Tue, March 1, 2011 2:06 pm, Courtney Bane wrote:
> The kernel driver for using the serial DCD pin as a PPS source didn't
> actually hit the mainline kernel until 2.6.34 (I think); it was the PPS
> framework that went in in 2.6.32. Additionally, it didn't get enabled in
> Debian until 2.6.37, which is currently only in unstable (hopefully it'll
> hit testing next week). Ubuntu has it enabled in the 2.6.35 kernel in
> 10.10 (aka Maverick).
> However, even with a kernel supporting PPS, you'll still need to rebuild
> NTP, since Debian's version doesn't have PPS support enabled. It should
> just be a matter of dropping the timepps.h header file in
> /usr/local/include, and rebuilding the package. The instructions linked
> to before also cover rebuilding ldattach; if you're running Squeeze (the
> newest stable version, released last month) or newer, you don't need to
> do that.
> My home time server is running Debian Squeeze, with the latest 2.6.37
> kernel pulled in from unstable. The only thing I've compiled myself was
> NTP. For configuring the serial port, I created an
> /etc/udev/rules.d/09-pps.rules file (pasted below); it sets up a /dev/gps0
> symlink to the appropriate serial port, enables PPS and low-latency on
> the serial port, and creates a /dev/gpspps0 symlink to the PPS device.
> also pasted the relevant output from "ntpq -p" to show that it's working.
> KERNEL=="ttyS1", SYMLINK+="gps0"
> KERNEL=="ttyS1", RUN+="/bin/setserial -v /dev/%k low_latency"
> KERNEL=="ttyS1", RUN+="/usr/sbin/ldattach pps /dev/%k"
> KERNEL=="pps0", OWNER="root", GROUP="tty", MODE="0660", SYMLINK+="gpspps0"
> $ ntpq -p
> remote refid st t when poll reach delay offset jitter
> oGPS_NMEA(0) .GPS. 0 l 5 16 377 0.000 0.001 0.002
> Courtney Bane
> "He that would make his own liberty secure, must guard even his enemy
> from oppression; for if he violates this duty, he establishes a precedent
> that will reach to himself." -- Thomas Paine
> pool mailing list pool at lists.ntp.org http://lists.ntp.org/listinfo/pool
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