Re: open SHM data only after cgps start

[Frank Nicholas]

If you’re still starting GPSd under SystemD, without modifying the service file 
to start GPSd at boot, and adding the flag to make it run continuously as a 
daemon, that is probably your issue.

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Thanks,
Frank

> On Feb 5, 2021, at 12:52 PM, Hans Kurscheidt <lve0200@gmail.com> wrote:
> 
> OK,
> 
> I am now more than ever convinced that there's an issue in gpsd!
> 
> 1): fresh & clean boot; sudo lsof | grep /dev/ttyACM0 (my device (ublox 6 via 
> USB)) => nothing open.
> 
> 2) starting my app; sudo lsof | grep /dev/ttyACM0 (my device (ublox 6)) => 
> nothing open
> 
> starting cgps in parallel; sudo lsof | grep /dev/ttyACM0
> gpsd        700           nobody    9u      CHR      166,0 0t0      14619 
> /dev/ttyACM0
> 
> my app starts to receive data as well, like cgps.
> 
> stop (^C) cgps
> 
> my app continues reading the buffer from /dev/ACM0; sudo lsof | grep 
> /dev/ttyACM0
> gpsd        700           nobody    9u      CHR      166,0 0t0      14619 
> /dev/ttyACM0
> 
> means although cgps has been closed, the fd remains open, (because my app is 
> still hanging on ??)
> 
> after a while, my app does not receive anymore data (most likely when buffer 
> has become empty); sudo lsof | grep /dev/ttyACM0 (my device (ublox 6)) => 
> nothing open.
> 
> To avoid any ambiguity coming from my app running the gps_get function as a 
> thread, I changed my SW and gps_get runs now as a plain vanilla function 
> under main.
> 
> RGDS
> 
> hk
> 
> 
>