OpenJDK-21.0.1
Introduction to OpenJDK
OpenJDK is an open-source implementation
of Oracle's Java Standard Edition platform.
OpenJDK is useful for developing
Java programs, and provides a complete
runtime environment to run Java programs.
![[Note]](../images/note.png)
Note
Development versions of BLFS may not build or run
some packages properly if LFS or dependencies have been updated
since the most recent stable versions of the books.
OpenJDK is GPL'd code, with a special exception made for non-free
projects to use these classes in their proprietary products.
In similar fashion to the LGPL, which allows non-free programs to link
to libraries provided by free software, the
GNU
General Public License, version 2, with the Classpath Exception
allows third party programs to use classes provided by free software
without the requirement that the third party software also be free. As
with the LGPL, any modifications made to the free software portions of a
third party application, must also be made freely available.
Note
The OpenJDK source includes a very
thorough, open source test suite using the
JTreg test harness. The testing instructions
below allow testing the just built JDK for reasonable compatibility
with the proprietary Oracle JDK. However, in order for an independent
implementation to claim compatibility, it must pass a proprietary
JCK/TCK test suite. No claims of
compatibility, or even partial compatibility, may be made without passing
an approved test suite.
Oracle does provide free community access, on a case by case basis, to
a closed toolkit to ensure 100% compatibility with its proprietary JDK.
Neither the binary version provided on the Java-21.0.1 page
nor the JVM built with the instructions below have been tested against
the
TCK. Any version that is built using the instructions given,
cannot claim to be compatible with the proprietary JDK, without the
user applying for, and completing the compatibility tests themselves.
With that in mind, the binaries produced using this build method are
regularly tested against the TCK by the members listed on the site
above. In addition to the community license above, an educational,
non-commercial license for the TCK can be obtained
here.
Package Information
Additional Downloads
Optional test harness
OpenJDK Dependencies
Required Dependencies
An existing binary (Java-21.0.1 or an earlier built
version of this package. The instructions below assume that
you are using Configuring the JAVA environment),
alsa-lib-1.2.10,
cpio-2.14,
Cups-2.4.7,
UnZip-6.0,
Which-2.21,
Xorg Libraries, and
Zip-3.0
Recommended
make-ca-1.13,
giflib-5.2.1,
HarfBuzz-8.3.0,
Little CMS-2.14,
libjpeg-turbo-3.0.1,
libpng-1.6.40, and
Wget-1.21.4
Optional
git-2.43.0,
Graphviz-9.0.0,
Mercurial-6.6,
ccache,
pandoc, and
pigz
Installation of OpenJDK
If you have downloaded the optional test harness, unpack it now:
tar -xf ../jtreg-7.2+1.tar.gz
Note
Before proceeding, you should ensure that your environment
PATH variable contains the location of the Java
compiler used for bootstrapping OpenJDK.
This is the only requirement for the environment. Modern Java
installations do not need JAVA_HOME and
CLASSPATH is not used here. Furthermore, OpenJDK
developers recommend unsetting JAVA_HOME.
The build system does not allow the -j switch in
MAKEFLAGS. See the command explanation for
--with-jobs=
for more information on customizing parallelization.
Configure and build the package with the following commands:
unset JAVA_HOME &&
bash configure --enable-unlimited-crypto \
--disable-warnings-as-errors \
--with-stdc++lib=dynamic \
--with-giflib=system \
--with-harfbuzz=system \
--with-jtreg=$PWD/jtreg \
--with-lcms=system \
--with-libjpeg=system \
--with-libpng=system \
--with-zlib=system \
--with-version-build="12" \
--with-version-pre="" \
--with-version-opt="" \
--with-cacerts-file=/etc/pki/tls/java/cacerts &&
make images
To test the results, you will need to execute the jtreg program.
You can set the number of concurrent tests by adding the
-conc:<X>
value in the below command (tests will run sequentially otherwise):
export JT_JAVA=$(echo $PWD/build/*/jdk) &&
jtreg/bin/jtreg -jdk:$JT_JAVA -automatic -ignore:quiet -v1 \
test/jdk:tier1 test/langtools:tier1 &&
unset JT_JAVA
For more control over the test suite, review the documentation
available in jtreg/doc/jtreg/usage.txt. To review
the results, see the files
JTreport/test_{jdk,langtools}/text/stats.txt and
JTreport/test_{jdk,langtools}/text/summary.txt.
You should expect to see around 60 failures and 10 errors.
Install the package with the following commands as the
root user:
install -vdm755 /opt/jdk-21.0.1+12 &&
cp -Rv build/*/images/jdk/* /opt/jdk-21.0.1+12 &&
chown -R root:root /opt/jdk-21.0.1+12 &&
for s in 16 24 32 48; do
install -vDm644 src/java.desktop/unix/classes/sun/awt/X11/java-icon${s}.png \
/usr/share/icons/hicolor/${s}x${s}/apps/java.png
doneNote
If you only wish to install the Java Runtime Environment, you can
substitute build/*/images/jre in the above
cp command.
There are now two OpenJDK SDKs installed
in /opt. You should decide on
which one you would like to use as the default. Normally, you would opt
for the just installed OpenJDK. If so, do
the following as the root
user:
ln -v -nsf jdk-21.0.1+12 /opt/jdk
If desired, you can create .desktop files to add entries
in the menu for java
and jconsole. The needed icons have already been
installed. As the root user:
mkdir -pv /usr/share/applications &&
cat > /usr/share/applications/openjdk-java.desktop << "EOF" &&
[Desktop Entry]
Name=OpenJDK Java 21.0.1 Runtime
Comment=OpenJDK Java 21.0.1 Runtime
Exec=/opt/jdk/bin/java -jar
Terminal=false
Type=Application
Icon=java
MimeType=application/x-java-archive;application/java-archive;application/x-jar;
NoDisplay=true
EOF
cat > /usr/share/applications/openjdk-jconsole.desktop << "EOF"
[Desktop Entry]
Name=OpenJDK Java 21.0.1 Console
Comment=OpenJDK Java 21.0.1 Console
Keywords=java;console;monitoring
Exec=/opt/jdk/bin/jconsole
Terminal=false
Type=Application
Icon=java
Categories=Application;System;
EOF
Command Explanations
bash configure...: the top level
configure is a wrapper around the autotools one.
It is not executable and must be run through bash.
--enable-unlimited-crypto: Because of limitations
on the usage of cryptography in some countries, there is the possibility
to limit the size of encryption keys and the use of some algorithms in a
policy file. This switch allows to ship a policy file with no
restriction. It is the responsibility of the user to ensure proper
adherence to the law.
--disable-warnings-as-errors: This switch disables
use of -Werror in the build.
--with-stdc++lib=dynamic: This switch forces the
build system to link to libstdc++.so (dynamic)
instead of libstdc++.a (static).
--with-jobs=<X>:
The -j passed to make does not work with make as
invoked here. By default, the build system will use the number of
CPUs - 1.
--with-jtreg=$PWD/jtreg: This switch tells
configure where to find jtreg. Omit if you have not downloaded the
optional test suite.
--with-{giflib,harfbuzz,lcms,libjpeg,libpng,zlib}=system:
These switches force the build system to use the system libraries instead
of the bundled versions.
--with-version-build: Currently, the build
system does not include the build number in the version string. It has
to be specified here.
--with-version-pre: This switch allows you to
prefix the version string with a custom string.
--with-version-opt: This switch allows you to add
an optional build description to the version string.
--with-cacerts-file=/etc/pki/tls/java/cacerts:
Specifies where to find a cacerts file,
/etc/pki/tls/java/ on a BLFS system. Otherwise, an
empty one is created. You can use the
/usr/sbin/make-ca --force command to generate it, once
you have installed the Java binaries.
--with-boot-jdk: This switch provides the
location of the temporary JDK. It is normally
not needed if java is found in the PATH.
Configuring OpenJDK
Configuration Information
Normally, the JAVA environment has been configured after installing
the binary version, and can be used with the just built package as well.
Review Configuring the JAVA environment in case you want to modify
something.
To test if the man pages are correctly installed, issue
source /etc/profile and man java
to display the respective man page.
Setting up the JRE Certificate Authority Certificates (cacerts) file
If you have run the instructions on the make-ca-1.13 page,
you only need to create a symlink in the default location for the
cacerts file. As user root:
ln -sfv /etc/pki/tls/java/cacerts /opt/jdk/lib/security/cacerts
To check the installation, issue:
cd /opt/jdk
bin/keytool -list -cacerts
At the prompt Enter keystore password:,
enter changeit (the default) or just press the
“Enter” key. If the cacerts file was
installed correctly, you will see a list of the certificates with
related information for each one. If not, you need to reinstall them.
Contents
Installed Programs: jar, jarsigner, java, javac, javadoc, javap, jcmd,
jconsole, jdb, jdeprscan, jdeps, jfr, jhsdb, jimage, jinfo,
jlink, jmap, jmod, jpackage, jps, jrunscript, jshell, jstack,
jstat, jstatd, jwebserver, keytool, rmiregistry, and serialver
Installed Libraries: 37 libraries in /opt/jdk-21.0.1+12/lib/
Installed Directory: /opt/jdk-21.0.1+12
Short Descriptions
jar |
combines multiple files into a single jar archive
|
jarsigner |
signs jar files and verifies the signatures and integrity
of a signed jar file
|
java |
launches a Java application by starting a Java runtime
environment, loading a specified class and invoking its main
method
|
javac |
reads class and interface definitions, written in the
Java programming language, and compiles them into bytecode
class files
|
javadoc |
parses the declarations and documentation comments in a
set of Java source files and produces a corresponding set of
HTML pages describing the classes, interfaces, constructors,
methods, and fields
|
javap |
disassembles a Java class file
|
jcmd |
is a utility to send diagnostic command requests to a running
Java Virtual Machine
|
jconsole |
is a graphical console tool to monitor and manage both
local and remote Java applications and virtual machines
|
jdb |
is a simple command-line debugger for Java classes
|
jdeprscan |
scans class or jar files for uses of deprecated API elements
|
jdeps |
shows the package-level or class-level dependencies of
Java class files
|
jfr |
is a tool for working with “Flight Recorder” files
|
jhsdb |
is a tool to analyze the content of a core dump from a
crashed Java Virtual Machine (JVM)
|
jimage |
is used to list, extract, verify, or get information about
modules in jimage format
|
jinfo |
prints Java configuration information for a given Java
process, core file, or a remote debug server
|
jlink |
is used to assemble and optimize a set of modules and their
dependencies into a custom runtime image
|
jmap |
prints shared object memory maps or heap memory details
of a given process, core file, or a remote debug server
|
jmod |
creates JMOD files and lists the content of existing JMOD files
|
jpackage |
generates java application packages and images
|
jps |
lists the instrumented JVMs on the target system
|
jrunscript |
is a command line script shell
|
jshell |
is an interactive tool for learning the Java programming
language and prototyping Java code
|
jstack |
prints Java stack traces of Java threads for a given
Java process, core file, or a remote debug server
|
jstat |
displays performance statistics for an instrumented JVM
|
jstatd |
is an RMI server application that monitors for the creation
and termination of instrumented JVMs
|
jwebserver |
provides a minimal HTTP server, designed to be used for
prototyping, testing, and debugging
|
keytool |
is a key and certificate management utility
|
rmiregistry |
creates and starts a remote object registry on the specified
port on the current host
|
serialver |
returns the serialVersionUID for one or more classes in a
form suitable for copying into an evolving class
|