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Re: [gpsd-dev] [gpsd-commit-watch] [SCM] GPSD branch, master, updated. r


From: Gary E. Miller
Subject: Re: [gpsd-dev] [gpsd-commit-watch] [SCM] GPSD branch, master, updated. release-3.11-46-g6a33950
Date: Wed, 27 Aug 2014 14:49:28 -0700

Yo Greg!

I never siad it workedopn NetBSD, just that the TIOCMIWAIT is ifdefed out.

So, looking forward to patches.

On Wed, 27 Aug 2014 08:30:25 -0400
Greg Troxel <address@hidden> wrote:

> 
> "Gary E. Miller" <address@hidden> writes:
> 
> > As recently discused, TIOCMIWAIT is not in the RFC2783 path!
> >
> > just look at the code!
> 
> I don't follow this at all.  I am looking at ppsthread.c on git
> master, and specifically at gpsd_ppsmonitor().
> 
> I see a loop which has ifdefs for TIOCMIWAIT, and then an ifdef for
> HAVE_SYS_TIMEPPS_H, and within that RFC2783 ifdef, further conditional
> behavior based on TIOCMIWAIT.
> 
> Reading the code, I don't see how it copes with a system that doesn't
> have TIOCMIWAIT and doesn't implement waiting on time_pps_fetch, which
> is what I remember being the issue last November.  I think what's
> needed is to delay for 100 ms or so when time_pps_fetch says no edge
> is available, and not to complain about that.
> 
> The other issue is that there's a lot of sanity checking going on
> (towards the bottom of the function) which is currently conditional on
> TIOCMIWAIT, but really shouldn't be.  I suspect that's something I did
> to ifdef out code that wouldn't build.  It seems that obtaining
> timestamps of edges (via either mechanism) should be entirely
> separated From gpsd looking at those edge timestamps and deciding
> what it thinks about them.
> 
> A final complexity is that with RFC2783, finding the header file
> doesn't imply that it will work, because on all systems we know
> about, it's an optional kernel feature.  I think that's handled
> right.   With TIOCMIWAIT, I don't know if there are systems that have
> the symbol defined in the .h file but don't implement it.
> 
> I suspect that if you were to #undef TIOCMIWAIT on your gentoo system,
> the code would build but then probably won't work right.  (I am
> guessing that Linux KPPS doesn't implement the optional CANWAIT
> facility, because ntpd doesn't use it and thus it wouldn't have
> helped make anything work.)




RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588

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