[ntp:questions] new driver development

Rob nomail at example.com
Thu Mar 17 20:29:29 UTC 2011

Harlan Stenn <stenn at ntp.org> wrote:
> Bruce,
> Please see http://support.ntp.org/bin/view/Dev/RefclockShmV2 and
> communicate with folks who have been thinking about this (me, Miroslav,
> Dave Hart, just to name the first 3 folks who come to mind).
> Making notes on either the above wiki topic or on a separate sub-topic
> might be even better, as that way other folks can easily see what's
> going on.
> I'm curious if we can support both POSIX and SVID SHM from the same
> codebase, and use a flag bit or a mode to select which one is used.

IMHO it HAS to be backward compatible.

E.g. gpsd uses the existing SHM interface, and while the maintainers
are probably very willing to change the interface when an improved
option is available, it is not practical to lock-step the upgrade of
ntpd beyond a certain version with the upgrade of gpsd.

So ntpd has to support the existing SHM interface for a while, and
there has to be a mechanism to detect if a newer interface is available.

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