So I came a little closer. Seems like I had QML-Debugging enabled in Projects -> Build -> QML debugging and profiling, which I was actually not interested in. I disabled it and then installed gdbserver on the device. I can now launch debug mode, but Valgrind still says Error reading debug symbols, plug I get a bunch of other error messages.
Could not load shared library symbols for 10 libraries, e.g. /usr/local/qt5.15/lib/libQt5Quick.so.5.
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?QML debugging is enabled. Only use this in a safe environment.
Could not load shared library symbols for 3 libraries, e.g. /usr/local/qt5.15/plugins/platforms/libqxcb.so.
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-pi'
Could not load shared library symbols for /usr/local/qt5.15/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for 2 libraries, e.g. /usr/local/qt5.15/qml/QtQuick.2/libqtquick2plugin.so.
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/qml/QtQuick/Window.2/libwindowplugin.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/qml/QtQuick/Timeline/libqtquicktimelineplugin.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for 3 libraries, e.g. /usr/local/qt5.15/qml/QtQuick/Controls.2/libqtquickcontrols2plugin.so.
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/qml/QtQuick/Templates.2/libqtquicktemplates2plugin.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/xcbglintegrations/libqxcb-egl-integration.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqgif.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqicns.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqico.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqjpeg.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for 2 libraries, e.g. /usr/local/qt5.15/plugins/imageformats/libqsvg.so.
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqtga.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqtiff.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqwbmp.so.
Do you need "set solib-search-path" or "set sysroot"?Could not load shared library symbols for /usr/local/qt5.15/plugins/imageformats/libqwebp.so.
I guess that there is some environment variable missing on the device. I have
SHELL=/bin/bash
LANGUAGE=de_DE.UTF-8
NO_AT_BRIDGE=1
PWD=/home/pi
LOGNAME=pi
XDG_SESSION_TYPE=tty
MOTD_SHOWN=pam
HOME=/home/pi
LANG=de_DE.UTF-8
LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:
SSH_CONNECTION=xxxx:xxxx:xxxx:xxxx::xxxx:xxxx:xxxx:xxxx 22
XDG_SESSION_CLASS=user
TERM=xterm-256color
USER=pi
SHLVL=1
XDG_SESSION_ID=5
XDG_RUNTIME_DIR=/run/user/1000
SSH_CLIENT=xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx 37756 22
LC_ALL=de_DE.UTF-8
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
SSH_TTY=/dev/pts/0
TEXTDOMAIN=Linux-PAM
_=/usr/bin/printenv
DISPLAY=:0
XDG_SESSION_TYPE=x11
I need to find a way to let Valgrind tell me the location of the errors. Else I will be searching forever...
