Does qtJambi work also for STM32MP1?

[EutronBonetz]

Do you know if it is possible to use qtJambi to link Qt5.15.3 application with Java in embedded MPU?
I'm trying to obtain a working version of qtJambi given JDK 18.0.2.1 and a cross-compiled version of Qt but i found out a lot o problems.

[omix]

I don't know if this is possible. Actually, I have no experience with embedded programming. But if you want to give it a try I am definitely interested in supporting you.
Several weeks ago, I started making QtJambi ready to work with GraalVM. Here, Java code is somehow converted to platform-dependent executable. Maybe, the difficulties were similar to yours.

At startup, i.e. when loading the first class by class loader, QtJambi searches for QtCore.dll library expected to be in java.library.path or in env:PATH. The library is loaded by System.load() with full path. The second expected library is QtJambi.dll. If it is not available on library path QtJambi tries to extract it from jar bundle to temporary directory. Then also QtJambi.dll is loade by full path. However on Android, all libraries are bundled into the application. Thus, QtJambi on Android just calls System.loadLibrary("Qt6Core"). It is basically possible to use QtJambi with static libraries. At least, I prepared it for working with static libraries but I never tested it.

The next thing to know is, QtJambi does a lot of Java reflection, uses method handles and needs JNI to call Java code from C++. This makes it extremely difficult to work with GraalVM. I don't know if this is a problem on embedded MPUs.

Well, the first thing to do is crosscompiling QtJambi's native components.

As I said, I would like to support your attempts in getting this working.

[cesarbonetz]

Did you try this line? ant -Dqmake=/home/cesarbonetz/STM32MPU_workspace/STM32MP1-Ecosystem-v4.1.0/Developer-Package/SDK/sysroots/cortexa7t2hf-neon-vfpv4-ostl-linux-gnueabi/usr/local/Qt-5.15.3/bin/qmake all

Yes, here is the buildLog
buildLog.txt

[cesarbonetz]

Done, i compiled Qt against linux x64. I tried to run "ant generate" but i find out the same error (Project ERROR: Unknown module(s) in QT: qml)
Here is the buildlog:
build_2023-02-19_21-43-39.txt
Sorry to bother you. I don't know what to do

[omix]

Ah, that's easy. QtJambi generator requires QtQml library and others. You cannot compile it if your Qt installation does not provide QtQml, QtNetwork, QtConcurrent and QtXml.

[EutronBonetz]

Hi omix! Still working on this project. I was able to run the "ant generate" command based on the main Qt folder (the one installed fully with Qt installer).
build_2023-02-27_11-19-54.log
Now i tried to run the command you suggested me: "ant -Dqmake=/home/eutron/Desktop/qtbase-everywhere-src-5.15.3/bin/usr/local/Qt5/bin/qmake library" and i got this error: "Caused by: java.lang.NullPointerException
at io.qt.tools.ant.InitializeBuildTask.analyzeLibinfix(InitializeBuildTask.java:2037)"
/home/eutron/Desktop/qtjambi/buildlogs/build_2023-02-27_12-29-49.log
Can you help me?

[EutronBonetz]

Here is the log with the error
build_2023-02-27_12-29-49.log

[omix]

It is doing libraryPath.listFiles() and libraryPath refers to:
/home/eutron/Desktop/qtbase-everywhere-src-5.15.3/bin/usr/local/Qt5/bin/usr/local/Qt5/lib

The result of libraryPath.listFiles() is used in a for-loop. However, obviously libraryPath.listFiles() returns null because the NullPointerException is thrown in the for loop condition. This only makes sense if libraryPath is not existing or is not a directory. Obviously, the path quoted above has a strange duplication. I think it should me /home/eutron/Desktop/qtbase-everywhere-src-5.15.3/bin/usr/local/Qt5/lib instead. Thus, your cross compiled Qt has a configuration error. I think I could give you a workaround for building QtJambi but I am sure the next issue is still waiting because your qmake's internal paths are missleading. When compiling any project with Qt, qmake generates makefiles based upon its configuration which is given by -query. I am absolutely sure, your qmake will produce makefiles with unexisting paths inside. You can try this by creating a simple example program and build it with qmake+make.

It's long time ago I built Qt from source by myself but I guess you specified Qt's prefix as relative path and did not run make install after compilation. Could this be the issue here?

You could specify all properties mentioned in the build log where the line ends with (from qmake -query) manually with the correct path. Do this in build.properties with -D. However, as I said, I am sure this will bring other issues because qmake is somehow corrupted.

[EutronBonetz]

It seems, QtJambi compiled successfully. Actually, the build process is not able to distinguish between Linux x64 and cross compiled Linux ARM. Thus, it bundles all native libraries to linux-x64 jars. That's something to be changed in the future.

When creating native bundles, build process starts qtjambi deployer app. This app requires QtJambi binaries corresponding to the operation system, i.e. x64. It tries to load the formerly built arm binaries and fails. That's all.

You can build java independently: ant library.java

Then, you have all native libraries and java modules compiled. You could try to load the example program on your ARM by using the jars in classpath and put the natives in the java.library.path or LD_LIBRARY_PATH.

I tried runnning ant library.java. Here is the log:
ant library.java BuildLog 10_03_2023.txt

It seems to me that te build work for x64 not for arm. I followed this step:
0) set both JAVA_HOME and my crosscompile toolchain dependecies

1. set QTDIR using Qtx64
2. run "Ant generate" using
3. unset QTDIR
4. set JAVA_HOME_TARGET (jdk-18.0.2.1+1_arm
5. run "ant -Dqmake=/path_to_qt_for_arm_lib/bin/qmake library
6. run "ant library.java"

Is it correct?
Can you tell me an easy way to verify if the output jar (where are they placed?) are ok for my architecture?

[omix]

I think the best is you build QtJambi completely with Qt x64 (ant all). When finished, call ant -Dqmake=arm/qmake library.native. With the patch above it should finish correctly.

[EutronBonetz]

I was able to run the Hello World!
Thank you very much.
If you want i can share with you the .jar and native /lib for STM32MP1 by WeTransfer or similar. Onestly i don't know how to upload on Maven...

[omix]

Perfect! No, I don't need the arm binaries. However, I would highly appreciate if you give me a short introduction how to crosscompile Qt for arm on Linux. What software do I need? Can I do it on Ubuntu? What are the individual steps. I know, many information could be found in www but I want to have it here in the thread.

[EutronBonetz]

Firstly, as you may have observed, I have to point it out that I am not an expert in cross-compilation. In any case, I would be very pleased to summarize what I have done in order to help others as well.
My goal was to compile Qt 5.15.13 for my MPU (STM32MP1 - 2xCortex A7 arm architecture).
This is the procedure i followed.

1. STM gave me the SDK based on my MPU. The SDK contains the cross-compiler toolchain for my host machine and the sysroot for the embedded hardware
2. From https://download.qt.io/archive/qt/5.15/5.15.3/ i downloaded the qtbase -> (base library is the only one i needed)
3. I extracted the tar/zip in a new directory: custom_path/qt_source_directory
4. I created another folder next to last directory (where the Qt will be installed after the compilation): custom_path/qt_install_directory
5. In the qt_source_directory i created a new mkspecs (custom_path/qt_source_directory/mkspecs) by copying the folder "linux-arm-gnueabi-g++". The new folder has a custom name (es. stmp32)
6. Inside this new folder i changed the "qmake.conf" file by using the parameters of my cross-compilation toolchain. Here below my configurations (added .txt in order to upload)
   qmake.conf.txt
7. "cd custom_path/qt_install_directory"
   7b) I launched my SDK.sh script in order to set additional crosscompile option as stated by STM (i think it is optional)
8. running "./custom_path/qt_sourche_directory/configure -opensource -confirm-license -release -xplatform stmp32 -nomake examples -nomake tests" (-opensource and -confirm-licenser required to avoid confirm and costs, the world -xplatoform refers to the mkspecs adopted, -nomake to avoid the compilation of tests and examples)
9. Wait for compilation to end
10. run "gmake"
11. run "gmake install"
12. At the end all the lib, qmake and others are inside custom_path/qt_install_directory

[proussel-matawan]

I was able to run the Hello World! Thank you very much. If you want i can share with you the .jar and native /lib for STM32MP1 by WeTransfer or similar. Onestly i don't know how to upload on Maven...

Hi all,
I know this discussion is old but I'm trying to replicate what you done here without much success... Could you provide some details on the exact setup you used (qtjambi version, output of host and target 'qmake -query') and the detailed commands you ran ?

I'm using debian 11 x86_64 with all qt5 packages also available for armhf architecture.

Host qmake -query returns :

philou@CIB-PHIROU-NB:~$ /usr/lib/x86_64-linux-gnu/qt5/bin/qmake -query
QT_SYSROOT:
QT_INSTALL_PREFIX:/usr
QT_INSTALL_ARCHDATA:/usr/lib/x86_64-linux-gnu/qt5
QT_INSTALL_DATA:/usr/share/qt5
QT_INSTALL_DOCS:/usr/share/qt5/doc
QT_INSTALL_HEADERS:/usr/include/x86_64-linux-gnu/qt5
QT_INSTALL_LIBS:/usr/lib/x86_64-linux-gnu
QT_INSTALL_LIBEXECS:/usr/lib/x86_64-linux-gnu/qt5/libexec
QT_INSTALL_BINS:/usr/lib/qt5/bin
QT_INSTALL_TESTS:/usr/tests
QT_INSTALL_PLUGINS:/usr/lib/x86_64-linux-gnu/qt5/plugins
QT_INSTALL_IMPORTS:/usr/lib/x86_64-linux-gnu/qt5/imports
QT_INSTALL_QML:/usr/lib/x86_64-linux-gnu/qt5/qml
QT_INSTALL_TRANSLATIONS:/usr/share/qt5/translations
QT_INSTALL_CONFIGURATION:/etc/xdg
QT_INSTALL_EXAMPLES:/usr/lib/x86_64-linux-gnu/qt5/examples
QT_INSTALL_DEMOS:/usr/lib/x86_64-linux-gnu/qt5/examples
QT_HOST_PREFIX:/usr
QT_HOST_DATA:/usr/lib/x86_64-linux-gnu/qt5
QT_HOST_BINS:/usr/lib/qt5/bin
QT_HOST_LIBS:/usr/lib/x86_64-linux-gnu
QMAKE_SPEC:linux-g++
QMAKE_XSPEC:linux-g++
QMAKE_VERSION:3.1
QT_VERSION:5.15.8

and target qmake -query :

QT_SYSROOT:
QT_INSTALL_PREFIX:/usr
QT_INSTALL_ARCHDATA:/usr/lib/arm-linux-gnueabihf/qt5
QT_INSTALL_DATA:/usr/share/qt5
QT_INSTALL_DOCS:/usr/share/qt5/doc
QT_INSTALL_HEADERS:/usr/include/arm-linux-gnueabihf/qt5
QT_INSTALL_LIBS:/usr/lib/arm-linux-gnueabihf
QT_INSTALL_LIBEXECS:/usr/lib/arm-linux-gnueabihf/qt5/libexec
QT_INSTALL_BINS:/usr/lib/qt5/bin
QT_INSTALL_TESTS:/usr/tests
QT_INSTALL_PLUGINS:/usr/lib/arm-linux-gnueabihf/qt5/plugins
QT_INSTALL_IMPORTS:/usr/lib/arm-linux-gnueabihf/qt5/imports
QT_INSTALL_QML:/usr/lib/arm-linux-gnueabihf/qt5/qml
QT_INSTALL_TRANSLATIONS:/usr/share/qt5/translations
QT_INSTALL_CONFIGURATION:/etc/xdg
QT_INSTALL_EXAMPLES:/usr/lib/arm-linux-gnueabihf/qt5/examples
QT_INSTALL_DEMOS:/usr/lib/arm-linux-gnueabihf/qt5/examples
QT_HOST_PREFIX:/usr
QT_HOST_DATA:/usr/lib/arm-linux-gnueabihf/qt5
QT_HOST_BINS:/usr/lib/qt5/bin
QT_HOST_LIBS:/usr/lib/arm-linux-gnueabihf
QMAKE_SPEC:linux-g++
QMAKE_XSPEC:linux-g++
QMAKE_VERSION:3.1
QT_VERSION:5.15.8

I think here QMAKE_XPSEC should be linux-arm-gnueabi-g++ without being sure.

Thanks,
Philippe

[omix]

I will bring a new QtJambi version in the next days where compatibility to other systems and architectures is improved.

[proussel-matawan]

Another note in case it helps for the next versions : when running ant library.native build fails because jni_md.h is not accessible. /usr/lib/jvm/java-17-openjdk-amd64/include is the only folder from openjdk listed in the gcc command line and jni_md.h is under /usr/lib/jvm/java-17-openjdk-amd64/include/linux.

[omix]

Yes, I know this.
The old project file was (src/cpp/QtJambi/configure.pri):

linux-g++* {
        INCLUDEPATH += $$quote($$JAVA_HOME_TARGET/include/linux)
}

I changed this to:

linux-* {
        INCLUDEPATH += $$quote($$JAVA_HOME_TARGET/include/linux)
}

Does this fix your issue?

[proussel-matawan]

It probably will but I won't be able to test immediately, the build is taking some time and I prefer not to break it voluntarily !

[proussel-matawan]

Hi, and thanks again for your help. I managed to build qtjambi for my target after several incantions of 'ant all', 'ant library.native' and others. I just saw that you released of new version, I'll try again with qtjambi 6.6.2 and open a ticket in case of problem.

I'll let you close this discussion.

Philippe

[proussel-matawan]

Great to here, thank you for the hard work. Philippe Le mer. 7 févr. 2024 à 16:31, Dr. Peter Droste ***@***.***> a écrit :

…

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[omix]

I am happy about a donation if you like my work.

[omix]

Independent from this, I am here for you if you're facing further issues.