OpenCPN driver for reference:

https://github.com/OpenCPN/OpenCPN/blob/master/src/garmin/jeeps/gpsapp.c

Running gpsd from git. I believe head is at 059d39d71f85bcb20da508243965a2910f0ed9d5 in my local copy.

Hardware is Garmin eTrek Legend Cx. I believe the log claims it is firmware version 2.60. It is plausible.

OS is gentoo on x64, with kernel 4.11.

I run gpsd as root, like this:
gpsd -N -D 1 /dev/ttyUSB0


I notice the following issues:

1. gpsd will receive data from the device. But as soon as I kill a client talking to gpsd, I cannot get more data from gpsd. I need to kill gpsd to connect to it again.


2. When killing gpsd (ctrl-c), I get
gpsd:WARN: shmctl for IPC_RMID failed, errno = 1 (Operation not permitted)


3. On restarting gpsd, I get:
gpsd:ERROR: shmget(0x47505344, 8936, 0666) for SHM export failed: File exists

A manual exorcism with "ipcrm -M 0x47505344" enables me to restart gpsd without error.


4. I will occasionally get the following from gpsd:
gpsd:WARN: Garmin: Unknown packet id: 0xf8, Sz: 0x27


I am attaching a log taken with
gpspipe -R localhost:2947 > gpd.dat