[LinuxPPS] LinuxPPS + ntpd coockbook

[Hal V. Engel]

On Wednesday 10 June 2009 11:00:31 am Felix Joussein wrote:
> Hello everyone,
>
> while goog'ling around for a up-to-data timex.h I found very precious
> informations regarding setting up a ntp server, which finally clarified
> all my questions of the past such as which hardware to use, how to
> compile ntpd correctly,...
>
> Maybe one could link to this page as a resource on how to use the
> working LinuxPPS in conjunction of it's mayor application ntpd into the
> wiki?
>
>
> Here's the link:
>
> http://www.mulder.franken.de/blog/2008/12/10/#ntpd-with-refclock-on-linux
>
>
>
> regards,
>
> Felix

This information has all been talked about on this list and in most cases in 
more detail.  Unfortunately not all of this info has made it into the LinuxPPS 
wiki.  For example the wiki does not have any information on the glibc 
nanosecond issues that started with kernel 2.6.26.  This should be part of the 
LinuxPPS NTPD support page since we know it has a significant impact on how 
well things work.  The fix recommended in the above web page it probably the 
best one since it avoids patching glibc and it should be part of the NTPD page 
on the wiki. 

There has also been a lot of stuff here about different CPUs and 
timers/counters that are also not in the wiki.  But I am not sure if any of 
this information belongs on the wiki.  However it would be nice if there were 
a single place on the web where this was documented (even the above link is 
missing a lot of info about this subject).  

One thing that is missing from both the wiki and the above web page is 
anything about fixing the convergence problem in newer (2.6.19 and later) 
kernels.  The fix is so simple it should only take one small paragraph to 
explain it.  Why not include this in the wiki someplace?

In addition, I sent a patch to the list for the Motorola Oncore section of the 
wiki with detailed configuration instructions for that refclock.  This pulled 
together information from various sources including information posted on 
Remco's blog, information from Reg and stuff that I learned among others and 
none of that information is posted yet perhaps because it was too detailed(?).  

So there is lots of stuff that could/should be in the wiki that is missing.

The flip side to all of this is that at some point the LinuxPPS patch set 
should be part of the kernel main line and the need for a LinuxPPS wiki should 
go away.  But when that happens I am concerned that a lot of valuable 
information that is posted there will be lost.  But perhaps the focus of the 
wiki will change to be more of a general howto for PPS and NTP on Linux which 
will be clearly needed.

Hal