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Re: [gpsd-dev] GPSd on FreeBSD

From: Gary E. Miller
Subject: Re: [gpsd-dev] GPSd on FreeBSD
Date: Mon, 9 Sep 2019 14:46:45 -0700

Yo Greg!

On Mon, 09 Sep 2019 17:39:09 -0400
Greg Troxel <address@hidden> wrote:

> "Gary E. Miller" <address@hidden> writes:
> >> I get..  
> > [...]  
> >> gpsd:WARN: PPS:/dev/pps0 die: no TIOMCIWAIT, nor RFC2783 CANWAIT
> >> gpsd:PROG: PPS:/dev/pps0 gpsd_ppsmonitor exited.  
> >
> > Your system PPS is not correctly configured.  I'm not familiar
> > enough with BSD to say where...  
> I am unsure what's different now between freebsd and netbsd, but my
> impression is that one does pps on serial by doing pps ioctls on a
> serial port, rather than a specific /dev entity just for pps edges
> derived from another /dev entity.

True for all platforms, except those that do not have full serial
ports, like the RaspBerry Pi.

> >> It seems it isn't actually opening /dev/pps0 (based on the -2 for
> >> FD)  
> >
> > No, re-read the message.  It just says it can not use TIOMCIWAIT.
> > It should use KPPS instead, which is better, but that also failed.
> > I'm not afmiliar enough with *BSD to know why, but it does work for
> > others.  
> AIUI, TIOMCIWAIT is an extension to the standards-defined PPS, and is
> present in Linux and OpenBSD, but not in NetBSD.

Yes, a non-standard extension.

> >> The PPS API does work on this device:
> >> [gps 7:35] ~/gpsd  
> >> >/usr/obj/arm-src/arm.armv7/tools/test/ppsapi/ppsapitest /dev/pps0
> >> > 
> >
> > I'm unfamiliar with ppsapitest.  What does "ppscheck /dev/pps0"
> > show?  
> ppsapitest probably tests to the spec.  I'm assuming ppscheck is from
> gpsd, and would test to what gpsd uses - of course quite relevant
> here.


> >> Examining the code shows a big chunk is Linux specific so I guess I
> >> will have to modify it but if someone has advice on what the "right
> >> way" to do is that would be great :)  
> >
> > When you compiled gpsd it auto-detects your system.  It will
> > autodetect many flavors of *BSD and work just fine.  
> The PPS code assumes there is some ioctl to "wait until a pps edge",
> not found in RFC?

That is one way.  The other is KPPS.  One or the other is required, having
both is optimal.  You get nothing unless you have one.

It looks like the host in question has the KPPS, of some sort...

> The ntpd that's part of NetBSD base understands PPS and works with PPS
> devices (without gpsd).  I would expect that FreeBSD base system ntpd,
> or FreeBSD ports ntpd would also do that.

That would be a good test to run.

> (The ioctl makes a lot of sense - I don't mean to knock it.  It's just
> that it's not in the PPS RFC, and thus can't be assumed to be
> present.)

Yup.  So gpsd tests for it at config time, as well as KPPS, and
adjusts to fit.  So not sure the issue here yet.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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