If you are eager to try out building OpenJDK, these simple steps works most of the time. They assume that you have installed Mercurial (and Cygwin if running on Windows) and cloned the top-level OpenJDK repository that you want to build.
Get the complete source code:
-bash get_source.sh
hg clone http://hg.openjdk.java.net/jdk10/masterRun configure:
bash configure
If configure fails due to missing dependencies (to either the toolchain, external libraries or the boot JDK), most of the time it prints a suggestion on how to resolve the situation on your platform. Follow the instructions, and try running bash configure again.
OpenJDK is a complex software project. Building it requires a certain amount of technical expertise, a fair number of dependencies on external software, and reasonably powerful hardware.
If you just want to use OpenJDK and not build it yourself, this document is not for you. See for instance OpenJDK installation for some methods of installing a prebuilt OpenJDK.
OpenJDK uses Mercurial for source control. The source code is contained not in a single Mercurial repository, but in a tree ("forest") of interrelated repositories. You will need to check out all of the repositories to be able to build OpenJDK. To assist you in dealing with this somewhat unusual arrangement, there are multiple tools available, which are explained below.
-In any case, make sure you are getting the correct version. At the OpenJDK Mercurial server you can see a list of all available forests. If you want to build an older version, e.g. JDK 8, it is recommended that you get the jdk8u forest, which contains incremental updates, instead of the jdk8 forest, which was frozen at JDK 8 GA.
Make sure you are getting the correct version. As of JDK 10, the source is no longer split into separate repositories so you only need to clone one single repository. At the OpenJDK Mercurial server you can see a list of all available forests. If you want to build an older version, e.g. JDK 8, it is recommended that you get the jdk8u forest, which contains incremental updates, instead of the jdk8 forest, which was frozen at JDK 8 GA.
If you are new to Mercurial, a good place to start is the Mercurial Beginner's Guide. The rest of this document assumes a working knowledge of Mercurial.
For a smooth building experience, it is recommended that you follow these rules on where and how to check out the source code.
@@ -152,45 +148,6 @@Failure to follow this procedure might result in hard-to-debug build problems.
-The simplest way to get the entire forest is probably to clone the top-level repository and then run the get_source.sh script, like this:
hg clone http://hg.openjdk.java.net/jdk9/jdk9
-cd jdk9
-bash get_source.shThe first time this is run, it will clone all the sub-repositories. Any subsequent execution of the script will update all sub-repositories to the latest revision.
-The hgforest.sh script is more expressive than get_source.sh. It takes any number of arguments, and runs hg with those arguments on each sub-repository in the forest. The get_source.sh script is basically a simple wrapper that runs either hgforest.sh clone or hgforest.sh pull -u.
Cloning the forest:
-hg clone http://hg.openjdk.java.net/jdk9/jdk9
-cd jdk9
-bash common/bin/hgforest.sh clonePulling and updating the forest:
-bash common/bin/hgforest.sh pull -uMerging over the entire forest:
-bash common/bin/hgforest.sh mergeThe trees extension is a Mercurial add-on that helps you deal with the forest. More information is available on the Code Tools trees page.
-Install the extension by cloning http://hg.openjdk.java.net/code-tools/trees and updating your .hgrc file. Here's one way to do this:
cd ~
-mkdir hg-ext
-cd hg-ext
-hg clone http://hg.openjdk.java.net/code-tools/trees
-cat << EOT >> ~/.hgrc
-[extensions]
-trees=~/hg-ext/trees/trees.py
-EOTThe trees extension needs to know the structure of the forest. If you have already cloned the entire forest using another method, you can initialize the forest like this:
-hg tconf --set --walk --depthOr you can clone the entire forest at once, if you substitute clone with tclone when cloning the top-level repository, e.g. like this:
hg tclone http://hg.openjdk.java.net/jdk9/jdk9In this case, the forest will be properly initialized from the start.
-The trees extensions supplement many common operations with a trees version by prefixing a t to the normal Mercurial command, e.g. tcommit, tstatus or tmerge. For instance, to update the entire forest:
hg tpull -uOpenJDK is a massive project, and require machines ranging from decent to powerful to be able to build in a reasonable amount of time, or to be able to complete a build at all.
We strongly recommend usage of an SSD disk for the build, since disk speed is one of the limiting factors for build performance.
@@ -327,8 +284,7 @@The minimum accepted version of gcc is 4.3. Older versions will not be accepted by configure.
However, gcc 4.3 is quite old and OpenJDK is not regularly tested on this version, so it is recommended to use a more modern gcc.
+The minimum accepted version of gcc is 4.7. Older versions will generate a warning by configure and are unlikely to work.
OpenJDK 9 includes patches that should allow gcc 6 to compile, but this should be considered experimental.
In general, any version between these two should be usable.