Cross-compile MySQL driver for RPi3

endr

Yes, I run it from Qt to the remote RPi3. The application runs flawless if I use the Desktop kit. When I use the kit I've made for the Raspberry pi 3 (that has always worked fine) I get that error

jsulm

@endr Does this file exist on your target device: libmysqlclient.so.18 ? If so where?

endr

If I copy :

libmysqlclient.a
libmysqlclient_r.a 
libmysqlclient_r.so 
libmysqlclient_r.so.18 
ibmysqlclient_r.so.18.0.0
libmysqlclient.so 
libmysqlclient.so.18 
libmysqlclient.so.18.0.0

to /usr/lib on my target device I get:

QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers:

otherwise, without copying the shared libraries on the remote device (trying to crosscompile them from the local machine) I keep getting:

/opt/MySqlTest/bin/MySqlTest: error while loading shared libraries: libmysqlclient.so.18: cannot open shared object file: No such file or directory
Application finished with exit code 127.

What can I do?

jsulm

@endr You can try to start your app like this:

QT_DEBUG_PLUGINS=1 && ./my_app

You will get a lot of output, post it here.

The libraries you're copying: are those for your target (ARM)?

endr

@jsulm
I connect in ssh to the RPi3, start the application as you suggested:

root@rpi3:/opt/MySqlTest/bin# QT_DEBUG_PLUGINS=1 && ./MySqlTest 
./MySqlTest: error while loading shared libraries: libmysqlclient.so.18: cannot open shared object file: No such file or directory

If I copy those shared libraries (from the libmysqlclient-dev package downloaded on a Raspbian OS) to /usr/lib I get this:

root@rpi3:/opt/MySqlTest/bin# QT_DEBUG_PLUGINS=1 && ./MySqlTest 
Unable to query physical screen size, defaulting to 100 dpi.
To override, set QT_QPA_EGLFS_PHYSICAL_WIDTH and QT_QPA_EGLFS_PHYSICAL_HEIGHT (in millimeters).
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers:

jsulm

@endr What does

ldd PATH_TO_YOUR_QT/plugins/sqldrivers/libqsqlmysql.so

on your RaspberryPi say?

endr

There is no sqldrivers directory in qt5/plugins, just those:

root@rpi3:/usr/lib/qt5/plugins# ls -l 
total 68
drwxr-xr-x 2 root root 4096 Jun 14 10:51 bearer
drwxr-xr-x 2 root root 4096 Jun 14 11:44 canbus
drwxr-xr-x 2 root root 4096 Jun 14 10:51 egldeviceintegrations
drwxr-xr-x 2 root root 4096 Jun 14 10:51 generic
drwxr-xr-x 2 root root 4096 Jun 14 12:23 geoservices
drwxr-xr-x 2 root root 4096 Jun 14 11:43 iconengines
drwxr-xr-x 2 root root 4096 Jun 14 12:33 imageformats
drwxr-xr-x 2 root root 4096 Jun 14 12:24 lipi_toolkit
drwxr-xr-x 2 root root 4096 Jun 14 12:08 mediaservice

What do I need to download?

jsulm

@endr How did you install Qt on RaspberryPi?

endr

I'm using Yocto, Qt5 is installed via the meta-qt5 layer during the bitbaking of the image

jsulm

@endr Well, then I don't know what exactly you need to install. Something with qt and mysql. On Ubuntu it is libqt5sql5-mysql package.