Custom build of OpenJDK providing Java support for ev3dev on the following devices:
- LEGO Mindstorms EV3, featuring a ARM926EJ-S CPU
Builds for older boards should work on newer boards, the performance might just be a bit lower.
| OpenJDK version | Platform | Type | VM | ev3dev-stretch | ev3dev-buster |
|---|---|---|---|---|---|
| OpenJDK 9 | EV3 | x86→ARM | C1 JIT | archived | N/A |
| OpenJDK 10 | EV3 | x86→ARM | C1 JIT | archived | N/A |
| OpenJDK 11 | EV3 | ARM→ARM | C1 JIT | ||
| OpenJDK 12 | EV3 | ARM→ARM | C1 JIT | ||
| OpenJDK 13 | EV3 | ARM→ARM | C1 JIT | ||
| OpenJDK 14 | EV3 | ARM→ARM | C1 JIT | ||
| OpenJDK 15 | EV3 | ARM→ARM | C1 JIT | ||
| OpenJDK tip (dev) | EV3 | ARM→ARM | C1 JIT |
See Docs
The build process produces these files:
| Name | File name | Summary | Where it runs | Who is it for | What is it useful for |
|---|---|---|---|---|---|
| JRI | jri-ev3.zip |
Minimal runtime | Brick | Java developer | Running Java programs on ev3dev. |
| JDK | jdk-ev3.zip |
Full JDK | Brick | ev3dev power user | Compiling Java programs directly on the brick. |
| JMODs | jmods-ev3.zip |
Runtime modules | Developer PC | both | Creating custom JRIs. |
JRI stands for "Java Runtime Image". The term itself is not specific to this project,
it is equivalent to Modular Run-Time Image.
To see which modules are included in our case, take a look at the JRI_MODULES variable in scripts/config.sh.
- Install Docker for your operating system.
- Follow this script:
# define parameters TARGET_WORKSPACE="$(pwd)/build" # 10 GB of free space should be sufficient, probably less TARGET_DEBIAN_VERSION="stretch" # stretch or buster TARGET_OPENJDK_VERSION="11" # 9, 10, 12, 13, 14 - retired, may not be working # 11, 15 - most likely working # loom or tip - experimental, may be broken # clone repository git clone https://github.com/ev3dev-lang-java/openjdk-ev3.git cd openjdk-ev3 # prepare working directory mkdir -p "$TARGET_WORKSPACE" chmod -R 777 "$TARGET_WORKSPACE" # docker may not share UID with the current user # build base system container docker build --build-arg DEBIAN_RELEASE="$TARGET_DEBIAN_VERSION" \ --build-arg ARCH="armel" \ --tag "ev3dev-lang-java:jdk-cross-$TARGET_DEBIAN_VERSION" \ --file ./system/Dockerfile.cross \ ./system # on top of that, create a build scripts container docker build --build-arg commit="$(git rev-parse HEAD)" \ --build-arg extra="Manual build by $(whoami)" \ --build-arg DEBIAN_RELEASE="$TARGET_DEBIAN_VERSION" \ --build-arg BUILD_TYPE="cross" \ --tag "ev3dev-lang-java:jdk-cross-build" \ ./scripts # now run the build docker run --rm \ --interactive \ --tty \ --volume "$TARGET_WORKSPACE:/build" \ --env JDKVER="$TARGET_OPENJDK_VERSION" \ --env JDKVM="client" \ --env JDKPLATFORM="ev3" \ --env JDKDEBUG="release" \ --env AUTOBUILD="1" \ ev3dev-lang-java:jdk-cross-build # finally, make workspace accessible for all users (i.e. current one too) and list files in its root chmod -R 777 "$TARGET_WORKSPACE" # and list the output directory (now it should contain three *-ev3.tar.gz files) ls "$TARGET_WORKSPACE"