Proposal - drop the GPSD JSON driver

Eric S. Raymond esr at
Thu Oct 20 10:57:07 UTC 2016

Hal Murray <hmurray at>:
> esr at said:
> >> So, we all vote for JSON in POSIX SHM?
> > I don't.  I think this is one of the very rare cases where passing a C stru=
> > ct as a binary blob makes sense.  We want to minimize offset and jitter and
> > there's no cross-architecture problem. 
> Don't forget to include a version number.  Or maybe 2.

First field, or fields.

> There is still a nasty problem of how to change the contents of that struct.  
> In general, you can't assume that you can update both ends at the same time.

I expect changes to be rare.  But yes.

> If you normally add fields, I think you can swap in new code on the source 
> side as long as the version info is handled properly.  I think you need 2 
> version numbers.  One is the current version.  The other is the oldest 
> version that will work.

That's a good plan.
		<a href="">Eric S. Raymond</a>

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