Re: [gpsd-dev] Updated docs on NTP segment management

[Miroslav Lichvar]

On Thu, Feb 26, 2015 at 06:01:57AM -0500, Eric S. Raymond wrote:
> Miroslav Lichvar <address@hidden>:
> > I think it would but how would it signal that the fields are set to
> > not use some random garbage the client had on stack? Include a
> > checksum?
> 
> That's easy.  Assuming we have the ntpd project's cooperation, we can 
> define a mode 2 that uses a leading segment of the dummy fields to pass 
> additional info.  Obvious tricks with unions apply.

How will gpsd know it's talking to an older ntpd that doesn't support
the new mode and is ignoring all samples? It could check if the valid field
is getting cleared, but that will happen also when ntpd isn't started
yet.

I think it's important to keep it compatible both ways.

-- 
Miroslav Lichvar