How to install JAVA JDK

The goal of this page is to describe the OpenJDK installation procedure on your STM32 MPU board and (native) desktop, in a Distribution Package environment. It is the "Open Standard Edition Java Development Kit" installation process. According to the OpenstLinux Weston software architecture, XWayland is used for all Java applications based on X11, which means AWT/SWING Java display/graphical applications. By default the Java Development Kit is installed on the rootfs partition of the target.

1 Prerequisites

1.1 Hardware prerequisites

• STM32MP157x-DKx Discovery kit Or aSTM32MP157x-EV1 Evaluation board
• a keyboard and a mouse connected to the board

1.2 Software prerequisites

The STM32MP1 Distribution Package must be installed on your host. To do this, follow the procedure described in the Install the STM32MP1 OpenSTLinux distribution article.

The Host OS Ubuntu release 18.04 and next is required

2 The yoctoproject meta-java

JAVA for Linux-based embedded systems is available as metadata in the Yocto project.

• Clone the following git repository into [your STM32MP1 Distribution path]/layers

PC $>cd [your STM32MP1 Distribution path]/layers
PC $>git clone git://git.yoctoproject.org/meta-java

Depending on the Yocto release, select the right branch. (for example, branch dunfell for the ecosystem release v2.0.0 )

The last commit tested is cf9604a4789801d9dfb0cb8ca134ff04b42ae161 : openjdk-8: remove -Werror

PC $>cd meta-java
PC $>git checkout  remotes/origin/dunfell 

You can see the list of available Yocto branches with the following command:

PC $>cd meta-java
PC $>git branch -a

 master
 remotes/origin/HEAD -> origin/master
 remotes/origin/dora
 remotes/origin/dunfell
 remotes/origin/g0hl1n/jdk14
 remotes/origin/krogoth
 remotes/origin/master
 remotes/origin/master-next
 remotes/origin/morty
 remotes/origin/pyro
 remotes/origin/rocko
 remotes/origin/sumo
 remotes/origin/thud
 remotes/origin/warrior
 remotes/origin/zeus

• If not already done, set up your build environment

PC $> cd [your STM32MP1 Distribution path]
PC $> source layers/meta-st/scripts/envsetup.sh
(Select for the DISTRO openstlinux-weston and for MACHINE stm32mp1)

• Add the meta layer in your Yocto environment

PC $> cd [your STM32MP1 Distribution path]/build-openstlinuxweston-stm32mp1
PC $> bitbake-layers add-layer [your STM32MP1 Distribution path]/meta-st/meta-java

• Define at least the following variables in your local.conf file

([your STM32MP1 Distribution path]/build-openstlinuxweston-stm32mp1/conf/local.conf)

#Possible provider: cacao-initial-native and jamvm-initial-native
PREFERRED_PROVIDER_virtual/java-initial-native = "cacao-initial-native"

#Possible provider: cacao-native and jamvm-native
PREFERRED_PROVIDER_virtual/java-native = "jamvm-native"

#Optional since there is only one provider for now
PREFERRED_PROVIDER_virtual/javac-native = "ecj-bootstrap-native"

• Include in your image the openjdk-8 component

PC $> cd [your STM32MP1 Distribution path]/meta-st/meta-st-openstlinux/recipes-st/images

• Edit the file st-image-weston.bb and add the following line under CORE_IMAGE_EXTRA_INSTALL

  openjdk-8 \
  openjdk-8-demo \

• Build the image

PC $> cd [your STM32MP1 Distribution path]/build-openstlinuxweston-stm32mp1
PC $> bitbake st-image-weston

3 Compilation and execution of some JAVA demos

• forkjoin benchmark Java application

Board $> cd /usr/lib/jvm/openjdk-8/sample/forkjoin/mergesort
Board $> javac MergeDemo.java
Board $> java MergeDemo 200 100 3 1 1 3
Running with parameters: 200 100 3 1 1 3
Time in milliseconds. Y-axis: number of elements. X-axis parallelism used.
            1    2    3
    200:   10    7    8
    300:   17   12   12
    400:   20   14   14
  Total:   47   33   34

• SampleTree Java application

Read the README.txt file for details. To execute in a Linux Weston console on the board, with a keyboard and a mouse.

Board $> cd /usr/lib/jvm/openjdk-8/demo/jfc/SampleTree
Board $> java -jar SampleTree.jar