How to build Qt for Raspberry Pi3

[amruz]

@sneubert i tried by writing these commands in additional startup commands in qt
set sysroot target:/
but the same warning is coming..
when i am running a console app it is getting displayed in the raspberry without any problems.
but for widget application

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).

is coming.
:(

[sneubert]

@amruz

ok, my answer was to solve the problem not beeing abel to debug your application:

Unable to find dynamic linker breakpoint function.
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.Could not load shared library symbols for 22 libraries, e.g. /usr/lib/arm-linux-gnueabihf/libarmmem.so.
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"? 

for the remaining message:

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).

take a look at previous posts in this forum, e.g.
https://forum.qt.io/topic/77387/eglfs-unable-to-query-physical-screen-size-defaulting-to-100-dpi

[Zevero]

Work around for arm_thumb error is to be found here
https://github.com/Kukkimonsuta/rpi-buildqt/pull/7

Following
https://github.com/Kukkimonsuta/rpi-buildqt/issues/8
I succeeded even in compiling 5.9 (arm_thumb work around was not necessary any more)

Both qtwebengine 5.8 and 5.9 work nicely and fast BUT mouse interaction does not work (only keyboard). Anybody had this experience? Very frustrating after all the trouble...