47 lines
2.2 KiB
Markdown
47 lines
2.2 KiB
Markdown
OpenJDK 21 is the latest Long-Term Support (LTS) release of the Java platform.
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For a list of major changes from OpenJDK 17 (java-17-openjdk), see the upstream
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release page for OpenJDK 21 and the preceding interim releases:
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* 18: https://openjdk.java.net/projects/jdk/18/
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* 19: https://openjdk.java.net/projects/jdk/19/
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* 20: https://openjdk.java.net/projects/jdk/20/
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* 21: https://openjdk.java.net/projects/jdk/21/
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# Rebuilding the OpenJDK package
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The OpenJDK packages are now created from a single build which is then
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packaged for different major versions of Red Hat Enterprise Linux
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(RHEL). This allows the OpenJDK team to focus their efforts on the
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development and testing of this single build, rather than having
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multiple builds which only differ by the platform they were built on.
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This does make rebuilding the package slightly more complicated than a
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normal package. Modifications should be made to the
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`java-21-openjdk-portable.specfile` file, which can be found with this
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README file in the source RPM or installed in the documentation tree
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by the `java-21-openjdk-headless` RPM.
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Once the modified `java-21-openjdk-portable` RPMs are built, they
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should be installed and will produce a number of tarballs in the
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`/usr/lib/jvm` directory. The `java-21-openjdk` RPMs can then be
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built, which will use these tarballs to create the usual RPMs found in
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RHEL. The `java-21-openjdk-portable` RPMs can be uninstalled once the
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desired final RPMs are produced.
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Note that the `java-21-openjdk.spec` file has a hard requirement on
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the exact version of java-21-openjdk-portable to use, so this will
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need to be modified if the version or rpmrelease values are changed in
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`java-21-openjdk-portable.specfile`.
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To reduce the number of RPMs involved, the `fastdebug` and `slowdebug`
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builds may be disabled using `--without fastdebug` and `--without
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slowdebug`.
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By default, the portable build on RHEL also uses a "devkit" (a
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toolchain and system libraries) to build. This aids reproducibility
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by removing build differences caused by differing system toolchains
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and libraries. This dependency can be dropped by defining 'centos' to
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a non-zero value (e.g. --define='centos 1') or a devkit can be built
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using the `openjdk-devkit.specfile` and associated patches.
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