Qt cross-compilation for Raspberry pi error: (gdbserver: not found)

[SoheilSabz]

I am using the QT Creator for my laptop (Linux LMDE 3 Cindy OS) And for Raspberry Cross-compiling.

I have installed the QT based of [this instruction][2] and by this setting:

    mkdir ~/raspi
    cd ~/raspi
    git clone https://github.com/raspberrypi/tools
    mkdir sysroot sysroot/usr sysroot/opt

    rsync -avz pi@raspberrypi_ip:/lib sysroot
    rsync -avz pi@raspberrypi_ip:/usr/include sysroot/usr
    rsync -avz pi@raspberrypi_ip:/usr/lib sysroot/usr
    rsync -avz pi@raspberrypi_ip:/opt/vc sysroot/opt
wget http://download.qt.io/official_releases/qt/5.12/5.12.3/single/ qt-everywhere-src-5.12.3.tar.xz
tar xvf  qt-everywhere-src-5.12.3.tar.xz
cd  qt-everywhere-src-5.12.3

./configure -release -opengl es2 -device linux-rasp-pi-g++
-device-option CROSS_COMPILE=~/raspi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf-
-sysroot ~/raspi/sysroot -opensource -confirm-license -skip qtwayland -skip qtlocation -skip qtscript -make libs -prefix /usr/local/qt5pi -extprefix ~/raspi/qt5pi -hostprefix ~/raspi/qt5 -no-use-gold-linker -v -no-gbm

    make
    make install

but when i go to my QT Creator and i have built a sample Qt Widget Application.
My desktop2.pro file is this kind:

#-------------------------------------------------
#
# Project created by QtCreator 2019-06-09T18:56:52
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = new_sd
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

CONFIG += c++11

SOURCES += \
        main.cpp \
        mainwindow.cpp

HEADERS += \
        mainwindow.h

FORMS += \
        mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /home/pi/Desktop/$${TARGET}/bin
#else: unix:!android: target.path = /home/so/Desktop/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

SO when i want to use my **Raspberry Pi ** and want to debug it , i get this Error:

11:56:57: Checking available ports...
11:56:58: Found 101 free ports.
11:56:58: Starting gdbserver --multi :10000...
11:56:58: Debugging starts
bash: line 0: exec: gdbserver: not found
11:56:58: Application finished with exit code 127.
11:56:58: Debugging has finished

And when i run the project via cross compilation into raspberry zero i get this error:

12:09:22: Starting /home/pi/Desktop/new_sd/bin/new_sd ...
QXcbConnection: Could not connect to display 
12:09:23: Remote process crashed.

so the qt setting is shown blown:

[![ qt setting][1]][1]

So what can i do to solve this problem?

Thanks.
[1]: https://i.stack.imgur.com/yQWP4.jpg
[2]: https://mechatronicsblog.com/cross-compile-and-deploy-qt-5-12-for-raspberry-pi/

[jsulm]

@SoheilSabz said in Qt cross-compilation for Raspberry pi error: (gdbserver: not found):

QXcbConnection: Could not connect to display

Do you have X11 server running on your RaspberryPi?

[Pablo J. Rogina]

@SoheilSabz

QXcbConnection: Could not connect to display

in addition to jsulm question of having X11 running in the RPi device, if you connected via ssh did you enabled X Forwarding for the session? i.e. ssh -X user@RPI.device

Regarding this issue bash: line 0: exec: gdbserver: not found
it looks like the path for GDB could not be the right one from the image you posted. Check this guide for instance, about the Qt Creator setup section -> Debuggers

[SoheilSabz]

@jsulm base of this link:

https://stackoverflow.com/questions/637005/how-to-check-if-x-server-is-running

I get this output:

pi@raspberrypi:~ $ ps -e 
  PID TTY          TIME CMD
    1 ?        00:00:04 systemd
    2 ?        00:00:00 kthreadd
    3 ?        00:00:00 kworker/0:0-cgr
    6 ?        00:00:00 mm_percpu_wq
    7 ?        00:00:01 ksoftirqd/0
    8 ?        00:00:00 kdevtmpfs
    9 ?        00:00:00 netns
   11 ?        00:00:00 khungtaskd
   12 ?        00:00:00 oom_reaper
   13 ?        00:00:00 writeback
   14 ?        00:00:00 kcompactd0
   15 ?        00:00:00 crypto
   16 ?        00:00:00 kblockd
   17 ?        00:00:00 watchdogd
   18 ?        00:00:00 rpciod
   19 ?        00:00:00 kworker/u3:0
   20 ?        00:00:00 xprtiod
   21 ?        00:00:00 kworker/u2:1-ev
   23 ?        00:00:00 kswapd0
   24 ?        00:00:00 nfsiod
   35 ?        00:00:00 kthrotld
   36 ?        00:00:00 iscsi_eh
   37 ?        00:00:00 DWC Notificatio
   38 ?        00:00:00 vchiq-slot/0
   39 ?        00:00:00 vchiq-recy/0
   40 ?        00:00:00 vchiq-sync/0
   41 ?        00:00:00 vchiq-keep/0
   42 ?        00:00:00 SMIO
   44 ?        00:00:00 mmc_complete
   45 ?        00:00:00 kworker/0:1H-mm
   47 ?        00:00:00 jbd2/mmcblk0p2-
   48 ?        00:00:00 ext4-rsv-conver
   49 ?        00:00:00 ipv6_addrconf
   71 ?        00:00:01 systemd-journal
   94 ?        00:00:00 systemd-udevd
  116 ?        00:00:00 kworker/u2:2-ev
  140 ?        00:00:00 SMIO
  141 ?        00:00:00 spi0
  150 ?        00:00:00 mmal-vchiq
  152 ?        00:00:00 mmal-vchiq
  153 ?        00:00:00 mmal-vchiq
  195 ?        00:00:02 systemd-timesyn
  222 ?        00:00:00 thd
  225 ?        00:00:00 rsyslogd
  226 ?        00:00:00 dbus-daemon
  245 ?        00:00:00 wpa_supplicant
  251 ?        00:00:00 cron
  262 ?        00:00:01 avahi-daemon
  267 ?        00:00:00 systemd-logind
  278 ?        00:00:00 rngd
  279 ?        00:00:00 avahi-daemon
  360 ?        00:00:00 irq/160-ads7846
  380 ?        00:00:00 sshd
  383 tty1     00:00:00 agetty
  384 ?        00:00:00 agetty
  522 ?        00:00:00 systemd
  525 ?        00:00:00 (sd-pam)
  553 ?        00:00:00 sshd
  563 ?        00:00:00 sshd
 1715 ?        00:00:00 sshd
 1725 ?        00:00:00 sshd
 1728 pts/0    00:00:00 bash
 1755 ?        00:00:00 kworker/0:0H
 1764 ?        00:00:00 sshd
 1774 ?        00:00:00 sshd
 2079 ?        00:00:00 kworker/0:1-eve
 2744 ?        00:00:00 kworker/0:2-eve
 2745 ?        00:00:00 sshd
 2755 ?        00:00:00 sshd
 2758 pts/1    00:00:00 bash
 2776 ?        00:00:00 kworker/0:2H
 2779 pts/1    00:00:00 ps
pi@raspberrypi:~ $ netstat -lp|grep -i x
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
Active UNIX domain sockets (only servers)
unix  2      [ ACC ]     STREAM     LISTENING     6657     -                    /run/systemd/journal/stdout
unix  2      [ ACC ]     STREAM     LISTENING     13895    522/systemd          /run/user/1000/systemd/private
unix  2      [ ACC ]     STREAM     LISTENING     13900    522/systemd          /run/user/1000/gnupg/S.gpg-agent.extra
unix  2      [ ACC ]     STREAM     LISTENING     13903    522/systemd          /run/user/1000/gnupg/S.gpg-agent
unix  2      [ ACC ]     STREAM     LISTENING     13905    522/systemd          /run/user/1000/gnupg/S.gpg-agent.ssh
unix  2      [ ACC ]     STREAM     LISTENING     13907    522/systemd          /run/user/1000/gnupg/S.gpg-agent.browser
unix  2      [ ACC ]     STREAM     LISTENING     6503     -                    /run/systemd/private
unix  2      [ ACC ]     SEQPACKET  LISTENING     6519     -                    /run/udev/control
unix  2      [ ACC ]     STREAM     LISTENING     9088     -                    /var/run/dbus/system_bus_socket
unix  2      [ ACC ]     STREAM     LISTENING     9091     -                    /run/thd.socket
unix  2      [ ACC ]     STREAM     LISTENING     9093     -                    /var/run/avahi-daemon/socket
unix  2      [ ACC ]     STREAM     LISTENING     6605     -                    /run/systemd/fsck.progress
pi@raspberrypi:~ $  nmap localhost|grep -i x
-bash: nmap: command not found

SO No X11 server running on my RaspberryPi, Why x 11 is important now?

[SGaist]

Hi,

Because if you are using the XCB plugin, it's mandatory.

[SoheilSabz]

@SGaist excuse me, but I don't get your answer.

If I must enable X Forwarding for the session, where this setting must be added into the Qtcreator software?

[SGaist]

Since you are using the xcb backend of Qt, then yes, a X11 server like Xorg is mandatory.