NTPD configuration with SHM Reference Clock Driver


Can anybody tell how to use SHM ref. clock driver ([url]http://doc.ntp.org/4.2.6p5/drivers/driver28.html[/url]) to pass time information to NTPD.

I need to develop an application that will get actual time from serial port(GPS) and pass this to NTPD.
I have went through some formus where I have read that I need to have an application that writes into a shared memory which is accessible to NTPD. If so what is the Key to be used.

Any help will be useful. Thanks.

I noticed the following error,

[code]addto_syslog: refclock_newpeer: clock type 28 invalid

addto_syslog: configuration of failed[/code]

Does this mean that in QNX, NTPD does not have shared memory reference clock driver support.