[LinuxPPS] Patches for kernel 2.6.26-rc8

[Hal V. Engel]

On Sunday 06 July 2008 07:14:15 am Bernhard Schiffner wrote:
> On Sunday 06 July 2008 10:31:38 Hal V. Engel wrote:
> ...
>
> > Second ntp appears to be running in microsecond mode rather than
> > nanosecond mode even though I built it against the new kernel header
> > files.  When I run ntptime I get:
> >
> >
> > ntp_gettime() returns code 0 (OK)
> >   time cc1a25a4.f3dc6000  Sat, Jul  5 2008  9:53:56.952, (.952581),
> >   maximum error 2561 us, estimated error 12 us
> > ntp_adjtime() returns code 0 (OK)
> >   modes 0x0 (),
> >   offset 72.000 us, frequency -24.429 ppm, interval 1 s,
> >   maximum error 2561 us, estimated error 12 us,
> >   status 0x1 (PLL),
> >   time constant 4, precision 1.000 us, tolerance 500 ppm,
> >
> >
> > As you can see the precision is 1.000 us.  I built ntp after setting up
> > the symllinks in /usr/include that are used to build the LinuxPPS
> > userland tools. I had expected that the ntp build would find STA_NANO
> > defined in /usr/include/timex.h and that it would do the correct thing. 
> > I also tried adding STA_NANO and the other related defines to
> > kernel/sys/timex.h in the ntp source tree but I still end up with a
> > non-nano ntp.   It appears there something else that I need to do to get
> > ntp into nanosecond mode but I have no idea what that would be.  Do I
> > need to do something to the kernel (I couldn't find any place to make any
> > config settings that looked like it would affect this)?  Do I need to
> > build a newer version of ntp (I have tried 4.2.4_p4 and 4.2.5p118)?  Or
> > do I need to use a commad line switch when starting ntpd or something in
> > the configuration file?
>
> Ther are (small but important) differerences between /usr/include/linux
> and /usr/src/kernel/include/linux.
> One is what the distributor cleaned up for your use, working with a lot of
> different kernels too. The other is the recent opinion of the
> kernel-community.
> Test this please to get it right.


What should I test?  Are you saying that I should build ntp without the 
symlinked directories?  I will give that a try.


> A symlink may help for a first shot, but don't trash the content
> of /usr/include/linux to fast.


The symlinks are temperary and strictly to build the LinuxPPS user land tools 
and (I think but maybe I am wrong) ntp.  If I leave them in place many other 
things on my system will go haywire since I run a source based distro (IE. I 
can not do any updates with these in place).  I personally don't like the fact 
that LinuxPPS currently requires these symlinked directories to build the 
userland tools and this is something that needs to be fixed hopefully sooner 
rather than later.  It clearly needs to be fixed before LinuxPPS becomes part 
of the kernel.  I have not changed /usr/include at all and as soon as I have a 
working ntp I will remove the symlinks and restore the standard directories.


At this point I am convinced that I don't understand how to build ntp to work 
with kernel 2.6.26-rc8 with the LinuxPPS patches.  This kernel by default is a 
nanokernel so at some point ntp will need to be fixed up to build correctly 
out of the box but that does not appear to be the case at this point even with 
the most recent ntp snapshot.  I have spent a lot of time on the net trying to 
find anything that might be useful about this.  Since all of the things I am 
finding are from the PPSKit time frame I have not found anything useful and 
most of it is totally wrong.


Hal
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