[LinuxPPS] refclock_nmea: cannot find PPS path "/dev/ttyS0" in the system

[Udo van den Heuvel]

Rodolfo Giometti wrote:
>> What else could I prepare?
> 
> Just kernel debugging messages. Maybe you can also enable refclock
> debugging messages...

Tried again today, dmesg gave after bootup (cut):

pps_core: netlink protocol 20 created
pps_core: LinuxPPS API ver. 2 registered
pps_core: Software ver. 3.1.0 - Copyright 2005-2007 Rodolfo Giometti
<giometti at linux.it>

[....]

serial_core: PPS source #0 "/dev/ttyS0" added to the system


Then I disabled my internet connection to reduce the amount of logging
and started ntpd:

May  9 16:55:04 epia ntpd[3383]: ntpd 4.2.4 at 1.1437-o Thu Jan 25 15:24:37
UTC 2007 (1)
May  9 16:55:04 epia ntpd[3384]: precision = 14.000 usec
May  9 16:55:04 epia ntpd[3384]: Listening on interface #0 wildcard,
0.0.0.0#123 Disabled
May  9 16:55:04 epia ntpd[3384]: Listening on interface #1 wildcard,
::#123 Disabled
May  9 16:55:05 epia ntpd[3384]: Listening on interface #2 sit0,
::192.168.10.98#123 Enabled
May  9 16:55:05 epia ntpd[3384]: Listening on interface #3 lo, ::1#123
Enabled
May  9 16:55:05 epia ntpd[3384]: Listening on interface #4 sit0,
::10.0.0.150#123 Enabled
May  9 16:55:05 epia ntpd[3384]: Listening on interface #5 sit0,
::127.0.0.1#123 Enabled
May  9 16:55:05 epia ntpd[3384]: Listening on interface #6 eth0,
fe80::240:63ff:fee9:176c#123 Enabled
May  9 16:55:05 epia ntpd[3384]: Listening on interface #7 eth0,
192.168.10.98#123 Enabled
May  9 16:55:05 epia ntpd[3384]: Listening on interface #8 lo,
127.0.0.1#123 Enabled
May  9 16:55:05 epia ntpd[3384]: kernel time sync status 0040
May  9 16:55:05 epia ntpd[3384]: refclock_nmea: cannot find PPS path
"/dev/ttyS0" in the system
May  9 16:55:05 epia ntpd[3384]: configuration of 127.127.20.0 failed
May  9 16:55:05 epia ntpd[3384]: refclock: no available PPS source in
the system
May  9 16:55:05 epia ntpd[3384]: configuration of 127.127.22.0 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 194.109.22.18
May  9 16:55:05 epia ntpd[3384]: configuration of 194.109.22.18 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 213.84.46.114
May  9 16:55:05 epia ntpd[3384]: configuration of 213.84.46.114 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 213.84.187.156
May  9 16:55:05 epia ntpd[3384]: configuration of 213.84.187.156 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 217.114.97.97
May  9 16:55:05 epia ntpd[3384]: configuration of 217.114.97.97 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 217.114.97.98
May  9 16:55:05 epia ntpd[3384]: configuration of 217.114.97.98 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 195.230.70.112
May  9 16:55:05 epia ntpd[3384]: configuration of 195.230.70.112 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 213.222.193.35
May  9 16:55:05 epia ntpd[3384]: configuration of 213.222.193.35 failed
May  9 16:55:05 epia ntpd[3384]: Cannot find existing interface for
address 217.20.117.92
May  9 16:55:05 epia ntpd[3384]: configuration of 217.20.117.92 failed
May  9 16:55:05 epia ntpd[3384]: frequency initialized 3.768 PPM from
/var/lib/ntp/drift
May  9 16:55:05 epia ntpd[3384]: Deleting interface #2 sit0,
::192.168.10.98#123, interface stats: received=0, sent=0, dropped=0,
active_time=1 secs
May  9 14:55:05 epia ntpd[3384]: Deleting interface #3 lo, ::1#123,
interface stats: received=0, sent=0, dropped=0, active_time=1 secs
May  9 14:55:05 epia ntpd[3384]: Deleting interface #4 sit0,
::10.0.0.150#123, interface stats: received=0, sent=0, dropped=0,
active_time=1 secs
May  9 14:55:06 epia ntpd[3384]: Deleting interface #5 sit0,
::127.0.0.1#123, interface stats: received=0, sent=0, dropped=0,
active_time=1 secs
May  9 14:55:06 epia ntpd[3384]: Deleting interface #6 eth0,
fe80::240:63ff:fee9:176c#123, interface stats: received=0, sent=0,
dropped=0, active_time=1 secs


So no /dev/ttyS0.
No PPS demug messages in dmesg.

What can I do to debug?
This machine runs OK with 2.6.20.7 and an older PPS patch. Serial setup
is standard.

Udo