Error deploying Qt5 e.g. - EGLFS: failed to open /dev/fb0

embdev

Dear fellow coders, I built Qt5 with the following configuration parameters, executed an example in Qt5 and met with an error:

(1) Executing Qt5 configuration parameters:

./configure -commercial -confirm-license -release -static -eglfs -linuxfb -opengl es2 -platform linux-
g++-64 -device linux-arm-hi3536-g++ -prefix /home/aa/Hi3536_SDK_V2.0.4/v1_qt5.7_arm -device-option CROSS_COMPILE=/opt/hisi-linux/x86-arm/arm-hisiv400-linux/bin/arm-hisiv400-linux-gnueabi- -skip doc -v -qreal float

(2) Executed an example in Qt 5

/mnt/v1_qt5.7_arm/examples/widgets/widgets/tetrix # ./tetrix

(3) Error executing ./tetrix

QIconvCodec::convertToUnicode: using Latin-1 for conversion, iconv_open failed
QIconvCodec::convertFromUnicode: using Latin-1 for conversion, iconv_open failed
EGLFS: Failed to open /dev/fb0
EGLFS: Can't continue without a display
Aborted

Could anyone advise if there's any solution to this error?

Thank you!

SGaist

Hi,

Do you have a device named /dev/fb0 ? If yes, do you have the rights to access it ?

embdev

@SGaist hi, I've a device in my embedded device and i'm also the root user #.

SGaist

Do you have anything else accessing that device ?

embdev

@SGaist i think I forgot to load my vendor framebuffer for this action. I ran a framebuffer in the background and was able to display the examples. Thanks!

embdev

@SGaist I did a reboot of my embedded device (via Putty device) and re-run the example tetrix (examples/widgets/widgets/tetrix) again and it seems that some fonts are missing. Basically I did the following actions:

Installed fontconfig and coped the folder [fonts] from /usr/shared/fonts into my [compiled Qt 5.7 fonts directory] i.e. /v1_qt5.7_arm/lib/fonts
Re-run the tetrix example again but still met with the following issues:

/mnt/v1_qt5.7_arm/examples/widgets/widgets/tetrix # ls
main.cpp          tetrixboard.cpp   tetrixpiece.h
tetrix            tetrixboard.h     tetrixwindow.cpp
tetrix.pro        tetrixpiece.cpp   tetrixwindow.h
/mnt/v1_qt5.7_arm/examples/widgets/widgets/tetrix # ./tetrix
QIconvCodec::convertToUnicode: using Latin-1 for conversion, iconv_open failed
QIconvCodec::convertFromUnicode: using Latin-1 for conversion, iconv_open failed
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).
QFontDatabase: Cannot find font directory /home/aa/Hi3536_SDK_V2.0.4.0/v1_qt5.7_arm/lib/fonts.
Note that Qt no longer ships fonts. Deploy some (from http://dejavu-fonts.org for example) or switch to fontconfig.

Do you've any advice for the issues:
(I) fonts issues - it seems that I need to re-configure and build my qmake again but do you've any idea how may I do that? i.e. copy the fontconfig sources into a newly unzipped Qt5 sources before configure-build?
(ii) Unable to query physical screen size, defaulting to 100 dpi?

Thank you!

SGaist

Temporarily put the fonts where QFontDatabase expects them.

Also you should compare the version of fontconfig you have installed with the one you used to build Qt.

embdev

@SGaist ok got it resolved. problem is that I do development on Ubuntu host before executing onto target. So during configuration and building Qt 5 sources, I need to add -prefix and -extprefix so that when I execute the Qt 5 app on my target, it's able to locate the fonts.