Qt 6 on the Raspberry Pi on eglfs
It has been some time since Qt 6 was released. Now that Qt 6.2 is almost out, I guess it is time to have a look at how Qt 6 runs on eglfs on a Raspberry Pi.
Building Qt 6
Qt 6 moved from qmake to cmake. This makes a difference when trying to build it and cross-build it. Instructions on how to build are already available online from many sources, so I won’t repeat the theory here. I just want to note a few key points.
Configuration
I configured this build in the simplest form. To start, I want to use eglfs on OpenGL ES.
Toolchain
Building Qt requires a toolchain for building on the host and a toolchain to build for the target (the Raspberry Pi in this case). The toolchain from the host is typically provided by your distro (I used Manjaro in this case), while the toolchain to cross-build for the Raspberry Pi is officially provided here. In the past years I had a lot of weird problems building with those toolchains, so I started to create my own. Never had any problem anymore. Here you can find the toolchains:
Please note that those toolchains are not always able to target every arch.
The one for Buster is the one I used in my build, and the target arch is armv8-a.
Dependencies
Dependencies are already listed elsewhere. I would only like to note one thing here: I had problems linking because of a missing symbol: qt_resourceFeatureZstd. According to the sources, it seems that resources are compiled by the rcc tool. My guess is that the host tools use zstd by default to compress when available, but this is a problem when zstd is available on the host and not available on the target. Therefore, I suspect you have to decide if you want zstd support or not before building Qt 6 for the host, and be coherent with the build for the target. I decided to add zstd.
Build Errors
I had a few build errors building Qt 6.2 beta3. Nothing particularly relevant, but I had to apply a few changes. I did not keep track of those changes, they were all trivial.
Build Qt Test App
Once the Qt builds are ready, it is time to run. For the moment, I only want to do a quick test of QML. In my build, I forgot to set eglfs as the default platform, but it can be set it in the environment. I wrote a simple app to test Qt Quick here. The animations are very simple, but I wrote it like this to see how well many items are handled and how well the uniform movement on the y axis is rendered.
NOTE: Unlike Qt5, Qt6 includes host tools and tools built for the target. This means you can build the test app on the target directly or cross-build it from your host. For the package below anyway, you’d need to have a system compatible with those binaries.
First App
This video shows a comparison of this Qt 6 build against Qt 5. It also shows the same benchmark app on Intel UHD and nVidia.
Download
If you want to test the build of Qt 6 on your rpi, you can download it from here:
Download Qt 6.2.0-rc1 for Raspberry OS Buster armv8-a
The package does not include the toolchain, that you can download from the other links, but includes the host build. I don’t think it will be of help, as it is built for my Manjaro context, but I placed it there anyway.
The positions of the directories are relevant:
- /opt/rpi/rpi-8.6.3: toolchain;
- /opt/Qt-x64-6.2.0-beta3: host build;
- /usr/local/Qt-rasp-6.2.0-beta3: position in the target;
- /opt/rpi/sysroot: sysroot for cross-building.
Runtime Context
The is the 3D environment as seen by Qt 6:
qt.rhi.general: Created OpenGL context QSurfaceFormat(version 2.0, options QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 0, stencilBufferSize 8, samples 0, swapBehavior QSurfaceFormat::DefaultSwapBehavior, swapInterval 1, colorSpace QColorSpace(), profile QSurfaceFormat::NoProfile) qt.rhi.general: OpenGL VENDOR: Broadcom RENDERER: VC4 V3D 2.1 VERSION: OpenGL ES 2.0 Mesa 19.3.2 qt.scenegraph.general: MSAA sample count for the swapchain is 1. Alpha channel requested = no. qt.scenegraph.general: rhi texture atlas dimensions: 2048x2048
Bye 😉
NOTE: this article is a follow-up this this discussion, and presents a more up to date approach.
20 thoughts on “Qt 6 on the Raspberry Pi on eglfs”
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Hi Luca,
did you manage to get audio works (with Alsa) ?
I’ve always managed to get alsa works in previous build (last with buster on April’22) but at the moment i couldn’t with latest Buster or Bullseye (neither Qt 5 noe Qt 6)
Thank you
Hello,
I’m sorry, I do not remember very well. I think Qt 5 worked properly with alsa. Qt 6 may require gstreamer instead, but I’m not sure. And I do not remember well if I tested it in Bullseye, probably only Buster.
Hello Luca,
I have been trying to compile qt 6.2.4 crossly on my hosy (ubuntu 22) for raspberry pi 4. I see some cmake problems. Like
CMake Error at CMakeLists.txt:158 (add_subdirectory):
The link interface of target “Platform” contains:
Threads::Threads
but the target was not found. Possible reasons include:
* There is a typo in the target name.
* A find_package call is missing for an IMPORTED target.
* An ALIAS target is missing.
CMake Error at cmake/FindWrapSystemHarfbuzz.cmake:56 (target_link_libraries):
The link interface of target “WrapSystemHarfbuzz::WrapSystemHarfbuzz”
contains:
PkgConfig::PC_HARFBUZZ
but the target was not found. Possible reasons include:
* There is a typo in the target name.
* A find_package call is missing for an IMPORTED target.
* An ALIAS target is missing.
Call Stack (most recent call first):
cmake/QtFindPackageHelpers.cmake:130 (find_package)
src/gui/configure.cmake:41 (qt_find_package)
cmake/QtFeature.cmake:573 (include)
src/CMakeLists.txt:12 (qt_feature_evaluate_features)
Have you ever seen these before ?
Could you please share your histroy or step that we can follow ?
Hello,
sorry, I did not encounter this issue before.
Hi Luca, very thanks for your sharing… I guess you can help on this:
I use your toolchain for mac raspberry gcc 8.3, is build for armv8a but i’m on raspberry 3, i tried with simple hello world and it worked. My goal is building qt6 for crosscompile. So i have your toolchain, Raspberry 3 Buster, sysroot on my mac, i did toolchain.cmake but in any contest that i try i never found EGL and GLESv2 librarys.
I have this li in my $SYSROOT/opt/vc/lib. Did you think that is for toolchain build for armv8? i don’t think due to hello world and other compilation work.
also from my mac to compile for raspberry Opengl call from triangle .c i use:
/opt/rpi/rpi-gcc-8.3.0/bin/arm-linux-gnueabihf-gcc -c triangle.c -o triangle.o -I/opt/rpi/sysroot/opt/vc/include
/opt/rpi/rpi-gcc-8.3.0/bin/arm-linux-gnueabihf-gcc -o triangle triangle.o -lbrcmEGL -lbrcmGLESv2 -lvcos -lbcm_host -lvchiq_arm -L/opt/rpi/sysroot/opt/vc/lib
Any suggestion?
Hello,
what does it mean “I never found”? What error is reported?
Configure summary:
Building for: linux-g++ (arm, CPU features: neon)
Compiler: gcc 8.3.0
Build options:
Mode …………………………….. release
Optimize release build for size …….. no
Fully optimize release builds (-O3) …. no
Building shared libraries ………….. yes
Using C standard ………………….. C11
Using C++ standard ………………… C++17
Using ccache ……………………… no
Using new DTAGS …………………… yes
Relocatable ………………………. yes
Using precompiled headers ………….. yes
Using LTCG ……………………….. no
Target compiler supports:
Extensions ……………………… NEON
Sanitizers:
Addresses ………………………. no
Threads ………………………… no
Memory …………………………. no
Fuzzer (instrumentation only) …….. no
Undefined ………………………. no
Build parts ………………………. libs
Qt modules and options:
Qt Concurrent …………………….. yes
Qt D-Bus …………………………. yes
Qt D-Bus directly linked to libdbus …. yes
Qt Gui …………………………… yes
Qt Network ……………………….. yes
Qt PrintSupport …………………… yes
Qt Sql …………………………… yes
Qt Testlib ……………………….. yes
Qt Widgets ……………………….. yes
Qt Xml …………………………… yes
Support enabled for:
Using pkg-config ………………….. yes
udev …………………………….. no
Using system zlib …………………. yes
Zstandard support …………………. no
Thread support ……………………. yes
Common build options:
Linker can resolve circular dependencies yes
Qt Core:
backtrace ………………………… yes
DoubleConversion ………………….. yes
Using system DoubleConversion …….. no
GLib …………………………….. yes
ICU ……………………………… yes
Using system libb2 ………………… no
Built-in copy of the MIME database ….. yes
Tracing backend ……………………
Logging backends:
journald ……………………….. no
syslog …………………………. no
slog2 ………………………….. no
PCRE2 ……………………………. yes
Using system PCRE2 ………………. no
CLONE_PIDFD support in forkfd ………. yes
Qt Sql:
SQL item models …………………… yes
Qt Network:
getifaddrs() ……………………… yes
IPv6 ifname ………………………. yes
libproxy …………………………. no
Linux AF_NETLINK ………………….. yes
OpenSSL ………………………….. yes
Qt directly linked to OpenSSL …….. no
OpenSSL 1.1 ………………………. yes
DTLS …………………………….. yes
OCSP-stapling …………………….. yes
SCTP …………………………….. no
Use system proxies ………………… yes
GSSAPI …………………………… no
Brotli Decompression Support ……….. no
Qt Gui:
Accessibility …………………….. yes
FreeType …………………………. yes
Using system FreeType ……………. yes
HarfBuzz …………………………. yes
Using system HarfBuzz ……………. yes
Fontconfig ……………………….. yes
Image formats:
GIF ……………………………. yes
ICO ……………………………. yes
JPEG …………………………… yes
Using system libjpeg …………… yes
PNG ……………………………. yes
Using system libpng ……………. yes
Text formats:
HtmlParser ……………………… yes
CssParser ………………………. yes
OdfWriter ………………………. yes
MarkdownReader ………………….. yes
Using system libmd4c …………… no
MarkdownWriter ………………….. yes
EGL ……………………………… no
OpenVG …………………………… no
OpenGL:
Desktop OpenGL ………………….. no
OpenGL ES 2.0 …………………… no
OpenGL ES 3.0 …………………… no
OpenGL ES 3.1 …………………… no
OpenGL ES 3.2 …………………… no
Vulkan …………………………… yes
Session Management ………………… yes
Features used by QPA backends:
evdev ……………………………. yes
libinput …………………………. no
INTEGRITY HID …………………….. no
mtdev ……………………………. no
tslib ……………………………. no
xkbcommon ………………………… yes
X11 specific:
XLib …………………………… yes
XCB Xlib ……………………….. no
EGL on X11 ……………………… no
xkbcommon-x11 …………………… no
xcb-sm …………………………. no
QPA backends:
DirectFB …………………………. no
EGLFS ……………………………. no
EGLFS details:
EGLFS OpenWFD …………………… no
EGLFS i.Mx6 …………………….. no
EGLFS i.Mx6 Wayland ……………… no
EGLFS RCAR ……………………… no
EGLFS EGLDevice …………………. no
EGLFS GBM ………………………. no
EGLFS VSP2 ……………………… no
EGLFS Mali ……………………… no
EGLFS Raspberry Pi ………………. no
EGLFS X11 ………………………. no
LinuxFB ………………………….. yes
VNC ……………………………… yes
VK_KHR_display ……………………. yes
QNX:
lgmon ………………………….. no
IMF ……………………………. no
XCB:
Using system-provided xcb-xinput ….. no
GL integrations:
GLX Plugin ……………………. no
XCB GLX …………………….. no
EGL-X11 Plugin ………………… no
Windows:
Direct 2D ………………………. no
Direct 2D 1.1 …………………… no
DirectWrite …………………….. no
DirectWrite 3 …………………… no
Qt Widgets:
GTK+ …………………………….. no
Styles …………………………… Fusion Windows
Qt Testlib:
Tester for item models …………….. yes
Qt PrintSupport:
CUPS …………………………….. no
Qt Sql Drivers:
DB2 (IBM) ………………………… no
InterBase ………………………… no
MySql ……………………………. no
OCI (Oracle) ……………………… no
ODBC …………………………….. no
PostgreSQL ……………………….. no
SQLite …………………………… yes
Using system provided SQLite ……… no
ERROR: Feature “opengl”: Forcing to “ON” breaks its condition:
QT_FEATURE_opengl_desktop OR QT_FEATURE_opengl_dynamic OR QT_FEATURE_opengles2
Condition values dump:
QT_FEATURE_opengl_desktop = “OFF”
QT_FEATURE_opengl_dynamic = “OFF”
QT_FEATURE_opengles2 = “OFF”
ERROR: The OpenGL functionality tests failed! You might need to modify the include and library search paths by editing QMAKE_INCDIR_OPENGL[_ES2], QMAKE_LIBDIR_OPENGL[_ES2] and QMAKE_LIBS_OPENGL[_ES2] in the mkspec for your platform.
CMake Error at cmake/QtBuildInformation.cmake:80 (message):
Check the configuration messages for an error that has occurred.
Call Stack (most recent call first):
cmake/QtBuildInformation.cmake:11 (qt_configure_print_summary)
cmake/QtBuildInternals/QtBuildInternalsConfig.cmake:472 (qt_print_feature_summary)
CMakeLists.txt:174 (qt_build_repo_end)
— Configuring incomplete, errors occurred!
I just found this in CMakeError.log:
Performing C++ SOURCE FILE Test HAVE_EGL failed with the following output:
Change Dir: /opt/rpi/qt6-rpi/CMakeFiles/CMakeTmp
Run Build Command(s):/usr/local/bin/ninja cmTC_61c5e && [1/2] Building CXX object CMakeFiles/cmTC_61c5e.dir/src.cxx.o
[2/2] Linking CXX executable cmTC_61c5e
FAILED: cmTC_61c5e
: && /opt/rpi/rpi-gcc-8.3.0/bin/arm-linux-gnueabihf-g++ –sysroot=/opt/rpi/sysroot -march=armv7-a -mfpu=neon -mfloat-abi=hard -Wl,-O1 -Wl,–hash-style=gnu -Wl,–as-needed -Wl,-rpath-link,/opt/rpi/sysroot/opt/vc/lib CMakeFiles/cmTC_61c5e.dir/src.cxx.o -o cmTC_61c5e && :
/opt/rpi/rpi-gcc-8.3.0/lib/gcc/arm-linux-gnueabihf/8.3.0/../../../../arm-linux-gnueabihf/bin/ld: CMakeFiles/cmTC_61c5e.dir/src.cxx.o: in function `main’:
src.cxx:(.text+0x1a): undefined reference to `eglDestroyContext’
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
Source file was:
#include
int main(int argc, char *argv[]) {
EGLint x = 0; EGLDisplay dpy = 0; EGLContext ctx = 0;
eglDestroyContext(dpy, ctx);
}
Performing C++ SOURCE FILE Test HAVE_GLESv2 failed with the following output:
Change Dir: /opt/rpi/qt6-rpi/CMakeFiles/CMakeTmp
Run Build Command(s):/usr/local/bin/ninja cmTC_85768 && [1/2] Building CXX object CMakeFiles/cmTC_85768.dir/src.cxx.o
[2/2] Linking CXX executable cmTC_85768
FAILED: cmTC_85768
: && /opt/rpi/rpi-gcc-8.3.0/bin/arm-linux-gnueabihf-g++ –sysroot=/opt/rpi/sysroot -march=armv7-a -mfpu=neon -mfloat-abi=hard -Wl,-O1 -Wl,–hash-style=gnu -Wl,–as-needed -Wl,-rpath-link,/opt/rpi/sysroot/opt/vc/lib CMakeFiles/cmTC_85768.dir/src.cxx.o -o cmTC_85768 && :
/opt/rpi/rpi-gcc-8.3.0/lib/gcc/arm-linux-gnueabihf/8.3.0/../../../../arm-linux-gnueabihf/bin/ld: CMakeFiles/cmTC_85768.dir/src.cxx.o: in function `main’:
src.cxx:(.text+0x10): undefined reference to `glUniform1f’
/opt/rpi/rpi-gcc-8.3.0/lib/gcc/arm-linux-gnueabihf/8.3.0/../../../../arm-linux-gnueabihf/bin/ld: src.cxx:(.text+0x18): undefined reference to `glClear’
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
Yes, the errors seem pretty clear:
undefined reference to `eglDestroyContext’
undefined reference to `glUniform1f’
undefined reference to `glClear’
So you’ll need to link to EGL and GLESv2 for the test to succeed.
Thanks for reply…!
i did it with no good result.
LIBEGL
MBP-di-carmine:arm-linux-gnueabihf$ ls -la /opt/rpi/sysroot/usr/lib/arm-linux-gnueabihf/libEGL*
lrwxr-xr-x 1 root wheel 11 Feb 10 16:02 /opt/rpi/sysroot/usr/lib/arm-linux-gnueabihf/libEGL.so -> libEGL.so.1
lrwxr-xr-x 1 root wheel 15 Feb 10 16:01 /opt/rpi/sysroot/usr/lib/arm-linux-gnueabihf/libEGL.so.1 -> libEGL.so.1.0.0
lrwxr-xr-x 1 root wheel 29 Feb 10 16:00 /opt/rpi/sysroot/usr/lib/arm-linux-gnueabihf/libEGL.so.1.0.0 -> ../../../opt/vc/lib/libEGL.so
LIBGLESv2
MBP-di-carmine:arm-linux-gnueabihf$ ls -la libGLESv2*
lrwxr-xr-x 1 root wheel 14 Feb 10 16:11 libGLESv2.so -> libGLESv2.so.2
lrwxr-xr-x 1 root wheel 18 Feb 10 16:11 libGLESv2.so.2 -> libGLESv2.so.2.0.0
lrwxr-xr-x 1 root wheel 31 Feb 10 15:18 libGLESv2.so.2.0.0 -> sysroot/opt/vc/lib/libGLESv2.so
do you see something wrong here?
No, but the problem seemed not to be a missing file, but a symbol that could not be found. The compilation line was not linking to EGL or GLESv2.
Links are already dead
Hello, if you are talking about the toolchians yes, probably my fault, sorry. Those are just links to the internal related articles. The articles are available in the blog. I’ll fix the links though, thanks for letting me know.
Links should be ok now. Thanks.
hi
could you share the configuration command
I’m sorry, I did not keep it. It was not different from the one you can find in many other articles anyway.
I make cross compile using your gcc toolchain
I just has the main issue here :
— Could NOT find EGL (missing: HAVE_EGL) (found version “1.5”)
I install all EGLdrivers (mesa , brcm)
and pass all paths to toochain.cmake
all packages can be found else EGL, GLES
No idea sorry. If configure cannot find EGL, it may mean the env is not setup properly. You can probably check for the exact error in the logs.
Did you solve this issue? I’m in the same situation!
If you still have this problem, maybe you can fix as I suggested to Mattia: set rpath.