[LinuxPPS] Linuxpps on 2.6.28 vs. ntpd 4.2.4p6

[Heiko Gerstung]

Hi everybody!

I am trying to prepare a new kernel for our series of NTP time server 
appliances called LANTIME (see our website if you are interested) but I 
have problems getting ntp-4.2.4p6 to work with my 2.6.28 kernel and the 
rc6 linuxpps patch.

What already works is that if I start ppsldisc /dev/ttyS0 on a console, 
I can see that assert and clear events are correctly recognized in 
/sys/class/pps/pps/assert and clear and they represent the 200ms pulse 
width we are using on our GPS receivers.

But for some it does not work when I start ppsldisc as a background 
process during startup. I can see that there are a number of events 
recorded because the assert file for example shows a timestamp and the 
event count, which can be #32 for example or #43 but does not recognize 
any further events until I "killall ppsldisc" and run ppsldisc on my 
console (in the foreground).

Additionally, when I start ntpd, it cannot initialize the Atom driver 
and the parse driver also cannot setup PPS usage:
> Jan 14 09:17:19 LantimeV5 ntpd[13940]: PARSE receiver #0: parse_start: 
> could not set up PPS: Invalid argument
> Jan 14 09:17:19 LantimeV5 ntpd[13940]: PARSE receiver #0: 
> parse_ppsapi: time_pps_getcap failed: Bad file descriptor
> Jan 14 09:17:19 LantimeV5 ntpd[13940]: refclock_atom: time_pps_create 
> failed: Inappropriate ioctl for device 
I am not running udev on my machine and therefore have to create the 
/dev/pps0 device node manually. I can see from /sys/class/pps/pps0/dev 
that this should be c254:0 and therefore run "mknod /dev/pps0 c 254 0" 
before doing anything else at startup.

What am I missing? First and foremost I would like to get ntpd to use 
the PPS stuff, but if someone has any hints on why ppsldisc does not 
work when it is sent into the background, I would be grateful for any 
hints.

Best Regards,
  Heiko