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<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" lang="" xml:lang="">
<head>
<meta charset="utf-8" />
<meta name="generator" content="pandoc" />
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes" />
<title>Building the JDK</title>
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<body>
<header id="title-block-header">
<h1 class="title">Building the JDK</h1>
</header>
<nav id="TOC" role="doc-toc">
<ul>
<li><a href="#tldr-instructions-for-the-impatient"
id="toc-tldr-instructions-for-the-impatient">TL;DR (Instructions for the
Impatient)</a></li>
<li><a href="#introduction" id="toc-introduction">Introduction</a></li>
<li><a href="#getting-the-source-code"
id="toc-getting-the-source-code">Getting the Source Code</a>
<ul>
<li><a href="#special-considerations"
id="toc-special-considerations">Special Considerations</a></li>
</ul></li>
<li><a href="#build-hardware-requirements"
id="toc-build-hardware-requirements">Build Hardware Requirements</a>
<ul>
<li><a href="#building-on-x86" id="toc-building-on-x86">Building on
x86</a></li>
<li><a href="#building-on-aarch64" id="toc-building-on-aarch64">Building
on aarch64</a></li>
<li><a href="#building-on-32-bit-arm"
id="toc-building-on-32-bit-arm">Building on 32-bit ARM</a></li>
</ul></li>
<li><a href="#operating-system-requirements"
id="toc-operating-system-requirements">Operating System Requirements</a>
<ul>
<li><a href="#windows" id="toc-windows">Windows</a></li>
<li><a href="#macos" id="toc-macos">macOS</a></li>
<li><a href="#linux" id="toc-linux">Linux</a></li>
<li><a href="#aix" id="toc-aix">AIX</a></li>
</ul></li>
<li><a href="#native-compiler-toolchain-requirements"
id="toc-native-compiler-toolchain-requirements">Native Compiler
(Toolchain) Requirements</a>
<ul>
<li><a href="#gcc" id="toc-gcc">gcc</a></li>
<li><a href="#clang" id="toc-clang">clang</a></li>
<li><a href="#apple-xcode" id="toc-apple-xcode">Apple Xcode</a></li>
<li><a href="#microsoft-visual-studio"
id="toc-microsoft-visual-studio">Microsoft Visual Studio</a></li>
<li><a href="#ibm-xl-cc" id="toc-ibm-xl-cc">IBM XL C/C++</a></li>
</ul></li>
<li><a href="#boot-jdk-requirements" id="toc-boot-jdk-requirements">Boot
JDK Requirements</a>
<ul>
<li><a href="#getting-jdk-binaries"
id="toc-getting-jdk-binaries">Getting JDK Binaries</a></li>
</ul></li>
<li><a href="#external-library-requirements"
id="toc-external-library-requirements">External Library Requirements</a>
<ul>
<li><a href="#freetype" id="toc-freetype">FreeType</a></li>
<li><a href="#fontconfig" id="toc-fontconfig">Fontconfig</a></li>
<li><a href="#cups" id="toc-cups">CUPS</a></li>
<li><a href="#x11" id="toc-x11">X11</a></li>
<li><a href="#alsa" id="toc-alsa">ALSA</a></li>
<li><a href="#libffi" id="toc-libffi">libffi</a></li>
</ul></li>
<li><a href="#build-tools-requirements"
id="toc-build-tools-requirements">Build Tools Requirements</a>
<ul>
<li><a href="#autoconf" id="toc-autoconf">Autoconf</a></li>
<li><a href="#gnu-make" id="toc-gnu-make">GNU Make</a></li>
<li><a href="#gnu-bash" id="toc-gnu-bash">GNU Bash</a></li>
</ul></li>
<li><a href="#running-configure" id="toc-running-configure">Running
Configure</a>
<ul>
<li><a href="#common-configure-arguments"
id="toc-common-configure-arguments">Common Configure Arguments</a></li>
<li><a href="#configure-control-variables"
id="toc-configure-control-variables">Configure Control
Variables</a></li>
</ul></li>
<li><a href="#running-make" id="toc-running-make">Running Make</a>
<ul>
<li><a href="#common-make-targets" id="toc-common-make-targets">Common
Make Targets</a></li>
<li><a href="#make-control-variables"
id="toc-make-control-variables">Make Control Variables</a></li>
</ul></li>
<li><a href="#running-tests" id="toc-running-tests">Running
Tests</a></li>
<li><a href="#signing" id="toc-signing">Signing</a>
<ul>
<li><a href="#macos-1" id="toc-macos-1">macOS</a></li>
</ul></li>
<li><a href="#cross-compiling"
id="toc-cross-compiling">Cross-Compiling</a>
<ul>
<li><a href="#specifying-the-target-platform"
id="toc-specifying-the-target-platform">Specifying the Target
Platform</a></li>
<li><a href="#boot-jdk-and-build-jdk"
id="toc-boot-jdk-and-build-jdk">Boot JDK and Build JDK</a></li>
<li><a href="#toolchain-considerations"
id="toc-toolchain-considerations">Toolchain Considerations</a></li>
<li><a href="#native-libraries" id="toc-native-libraries">Native
Libraries</a></li>
<li><a href="#verifying-the-build"
id="toc-verifying-the-build">Verifying the Build</a></li>
<li><a href="#cross-compiling-the-easy-way"
id="toc-cross-compiling-the-easy-way">Cross-Compiling the Easy
Way</a></li>
<li><a href="#considerations-for-specific-targets"
id="toc-considerations-for-specific-targets">Considerations for Specific
Targets</a></li>
</ul></li>
<li><a href="#build-performance" id="toc-build-performance">Build
Performance</a>
<ul>
<li><a href="#disk-speed" id="toc-disk-speed">Disk Speed</a></li>
<li><a href="#virus-checking" id="toc-virus-checking">Virus
Checking</a></li>
<li><a href="#ccache" id="toc-ccache">Ccache</a></li>
<li><a href="#precompiled-headers"
id="toc-precompiled-headers">Precompiled Headers</a></li>
<li><a href="#icecc-icecream" id="toc-icecc-icecream">Icecc /
Icecream</a></li>
<li><a href="#using-the-javac-server"
id="toc-using-the-javac-server">Using the javac Server</a></li>
<li><a href="#building-the-right-target"
id="toc-building-the-right-target">Building the Right Target</a></li>
</ul></li>
<li><a href="#troubleshooting"
id="toc-troubleshooting">Troubleshooting</a>
<ul>
<li><a href="#locating-the-source-of-the-error"
id="toc-locating-the-source-of-the-error">Locating the Source of the
Error</a></li>
<li><a href="#fixing-unexpected-build-failures"
id="toc-fixing-unexpected-build-failures">Fixing Unexpected Build
Failures</a></li>
<li><a href="#specific-build-issues"
id="toc-specific-build-issues">Specific Build Issues</a></li>
<li><a href="#getting-help" id="toc-getting-help">Getting Help</a></li>
</ul></li>
<li><a href="#reproducible-builds"
id="toc-reproducible-builds">Reproducible Builds</a></li>
<li><a href="#hints-and-suggestions-for-advanced-users"
id="toc-hints-and-suggestions-for-advanced-users">Hints and Suggestions
for Advanced Users</a>
<ul>
<li><a href="#bash-completion" id="toc-bash-completion">Bash
Completion</a></li>
<li><a href="#using-multiple-configurations"
id="toc-using-multiple-configurations">Using Multiple
Configurations</a></li>
<li><a href="#handling-reconfigurations"
id="toc-handling-reconfigurations">Handling Reconfigurations</a></li>
<li><a href="#using-fine-grained-make-targets"
id="toc-using-fine-grained-make-targets">Using Fine-Grained Make
Targets</a></li>
</ul></li>
<li><a href="#understanding-the-build-system"
id="toc-understanding-the-build-system">Understanding the Build
System</a>
<ul>
<li><a href="#configurations"
id="toc-configurations">Configurations</a></li>
<li><a href="#build-output-structure"
id="toc-build-output-structure">Build Output Structure</a></li>
<li><a href="#fixpath" id="toc-fixpath">Fixpath</a></li>
<li><a href="#native-debug-symbols" id="toc-native-debug-symbols">Native
Debug Symbols</a></li>
<li><a href="#autoconf-details" id="toc-autoconf-details">Autoconf
Details</a></li>
<li><a href="#developing-the-build-system-itself"
id="toc-developing-the-build-system-itself">Developing the Build System
Itself</a></li>
</ul></li>
<li><a href="#contributing-to-the-jdk"
id="toc-contributing-to-the-jdk">Contributing to the JDK</a></li>
<li><a href="#editing-this-document"
id="toc-editing-this-document">Editing This Document</a></li>
</ul>
</nav>
<h2 id="tldr-instructions-for-the-impatient">TL;DR (Instructions for the
Impatient)</h2>
<p>If you are eager to try out building the JDK, these simple steps work
most of the time. They assume that you have installed Git (and Cygwin,
MSYS2 or WSL if running on Windows), and want to clone the main-line JDK
repository.</p>
<ol type="1">
<li><p><a href="#getting-the-source-code">Get the complete source
code</a>:<br />
<code>git clone https://git.openjdk.org/jdk</code></p></li>
<li><p><a href="#running-configure">Run configure</a>:<br />
<code>bash configure</code></p>
<p>If <code>configure</code> fails due to missing dependencies (to
either the <a
href="#native-compiler-toolchain-requirements">toolchain</a>, <a
href="#build-tools-requirements">build tools</a>, <a
href="#external-library-requirements">external libraries</a> or the <a
href="#boot-jdk-requirements">boot JDK</a>), most of the time it prints
a suggestion on how to resolve the situation on your platform. Follow
the instructions, and try running <code>bash configure</code>
again.</p></li>
<li><p><a href="#running-make">Run make</a>:<br />
<code>make images</code></p></li>
<li><p>Verify your newly built JDK:<br />
<code>./build/*/images/jdk/bin/java -version</code></p></li>
<li><p><a href="#running-tests">Run basic tests</a>:<br />
<code>make test-tier1</code></p></li>
</ol>
<p>If any of these steps failed, or if you want to know more about build
requirements or build functionality, please continue reading this
document.</p>
<h2 id="introduction">Introduction</h2>
<p>The JDK 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.</p>
<p>If you just want to use the JDK and not build it yourself, this
document is not for you. See for instance <a
href="https://openjdk.org/install">OpenJDK installation</a> for some
methods of installing a prebuilt JDK.</p>
<h2 id="getting-the-source-code">Getting the Source Code</h2>
<p>Make sure you are getting the correct version. At the <a
href="https://git.openjdk.org/">OpenJDK Git site</a> you can see a list
of all available repositories. Commonly used repositories are:</p>
<ul>
<li><p>The <a href="https://openjdk.org/projects/jdk">JDK Project</a>
(the main-line currently in development):
https://git.openjdk.org/jdk</p></li>
<li><p>The <a href="https://openjdk.org/projects/jdk-updates/">JDK
Updates Project</a>, which has one repository per update release, e.g.
https://git.openjdk.org/jdk17u for JDK 17.</p></li>
</ul>
<p>If you want to build an older version, e.g. JDK 17, it is strongly
recommended that you use the JDK Updates repository, e.g. the
<code>jdk17u</code>, which contains incremental updates, instead of the
JDK Project repository <code>jdk17</code>, which was frozen at JDK 17
GA.</p>
<p>If you are new to Git, a good place to start is the book <a
href="https://git-scm.com/book/en/v2">Pro Git</a>. The rest of this
document assumes a working knowledge of Git.</p>
<h3 id="special-considerations">Special Considerations</h3>
<p>For a smooth building experience, it is recommended that you follow
these rules on where and how to check out the source code.</p>
<ul>
<li><p>Do not check out the source code in a path which contains spaces.
Chances are the build will not work. This is most likely to be an issue
on Windows systems.</p></li>
<li><p>Do not check out the source code in a path which has a very long
name or is nested many levels deep. Chances are you will hit an OS
limitation during the build.</p></li>
<li><p>Put the source code on a local disk, not a network share. If
possible, use an SSD. The build process is very disk intensive, and
having slow disk access will significantly increase build times. If you
need to use a network share for the source code, see below for
suggestions on how to keep the build artifacts on a local disk.</p></li>
<li><p>On Windows, if using <a href="#cygwin">Cygwin</a>, extra care
must be taken to make sure the environment is consistent. It is
recommended that you follow this procedure:</p>
<ul>
<li><p>Create the directory that is going to contain the top directory
of the JDK clone by using the <code>mkdir</code> command in the Cygwin
bash shell. That is, do <em>not</em> create it using Windows Explorer.
This will ensure that it will have proper Cygwin attributes, and that
it's children will inherit those attributes.</p></li>
<li><p>Do not put the JDK clone in a path under your Cygwin home
directory. This is especially important if your user name contains
spaces and/or mixed upper and lower case letters.</p></li>
<li><p>You need to install a git client. You have two choices, Cygwin
git or Git for Windows. Unfortunately there are pros and cons with each
choice.</p>
<ul>
<li><p>The Cygwin <code>git</code> client has no line ending issues and
understands Cygwin paths (which are used throughout the JDK build
system). However, it does not currently work well with the Skara CLI
tooling. Please see the <a
href="https://wiki.openjdk.org/display/SKARA/Skara#Skara-Git">Skara wiki
on Git clients</a> for up-to-date information about the Skara git client
support.</p></li>
<li><p>The <a href="https://gitforwindows.org">Git for Windows</a>
client has issues with line endings, and do not understand Cygwin paths.
It does work well with the Skara CLI tooling, however. To alleviate the
line ending problems, make sure you set <code>core.autocrlf</code> to
<code>false</code> (this is asked during installation).</p></li>
</ul></li>
</ul>
<p>Failure to follow this procedure might result in hard-to-debug build
problems.</p></li>
</ul>
<h2 id="build-hardware-requirements">Build Hardware Requirements</h2>
<p>The JDK 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.</p>
<p>We <em>strongly</em> recommend usage of an SSD disk for the build,
since disk speed is one of the limiting factors for build
performance.</p>
<h3 id="building-on-x86">Building on x86</h3>
<p>At a minimum, a machine with 2-4 cores is advisable, as well as 2-4
GB of RAM. (The more cores to use, the more memory you need.) At least 6
GB of free disk space is required.</p>
<p>Even for 32-bit builds, it is recommended to use a 64-bit build
machine, and instead create a 32-bit target using
<code>--with-target-bits=32</code>.</p>
<p>Note: The Windows 32-bit x86 port is deprecated and may be removed in
a future release.</p>
<h3 id="building-on-aarch64">Building on aarch64</h3>
<p>At a minimum, a machine with 8 cores is advisable, as well as 8 GB of
RAM. (The more cores to use, the more memory you need.) At least 6 GB of
free disk space is required.</p>
<p>If you do not have access to sufficiently powerful hardware, it is
also possible to use <a href="#cross-compiling">cross-compiling</a>.</p>
<h4 id="branch-protection">Branch Protection</h4>
<p>In order to use Branch Protection features in the VM,
<code>--enable-branch-protection</code> must be used. This option
requires C++ compiler support (GCC 9.1.0+ or Clang 10+). The resulting
build can be run on both machines with and without support for branch
protection in hardware. Branch Protection is only supported for Linux
targets.</p>
<h3 id="building-on-32-bit-arm">Building on 32-bit ARM</h3>
<p>This is not recommended. Instead, see the section on <a
href="#cross-compiling">Cross-compiling</a>.</p>
<h2 id="operating-system-requirements">Operating System
Requirements</h2>
<p>The mainline JDK project supports Linux, macOS, AIX and Windows.
Support for other operating system, e.g. BSD, exists in separate "port"
projects.</p>
<p>In general, the JDK can be built on a wide range of versions of these
operating systems, but the further you deviate from what is tested on a
daily basis, the more likely you are to run into problems.</p>
<p>This table lists the OS versions used by Oracle when building the
JDK. Such information is always subject to change, but this table is up
to date at the time of writing.</p>
<table>
<thead>
<tr class="header">
<th>Operating system</th>
<th>Vendor/version used</th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td>Linux/x64</td>
<td>Oracle Enterprise Linux 6.4 / 8.x</td>
</tr>
<tr class="even">
<td>Linux/aarch64</td>
<td>Oracle Enterprise Linux 7.6 / 8.x</td>
</tr>
<tr class="odd">
<td>macOS</td>
<td>macOS 13.x (Ventura)</td>
</tr>
<tr class="even">
<td>Windows</td>
<td>Windows Server 2016</td>
</tr>
</tbody>
</table>
<p>The double version numbers for Linux are due to the hybrid model used
at Oracle, where header files and external libraries from an older
version are used when building on a more modern version of the OS.</p>
<p>The Build Group has a wiki page with <a
href="https://wiki.openjdk.org/display/Build/Supported+Build+Platforms">Supported
Build Platforms</a>. From time to time, this is updated by contributors
to list successes or failures of building on different platforms.</p>
<h3 id="windows">Windows</h3>
<p>Windows XP is not a supported platform, but all newer Windows should
be able to build the JDK. (Note: The Windows 32-bit x86 port is
deprecated and may be removed in a future release.)</p>
<p>On Windows, it is important that you pay attention to the
instructions in the <a href="#special-considerations">Special
Considerations</a>.</p>
<p>Windows is the only non-POSIX OS supported by the JDK, and as such,
requires some extra care. A POSIX support layer is required to build on
Windows. Currently, the supported such layers are Cygwin, MSYS2 and
Windows Subsystem for Linux (WSL). Of these, Cygwin is the one that has
received the most real-world testing and is likely to cause least
trouble.</p>
<p>Internally in the build system, all paths are represented as
Unix-style paths, e.g. <code>/cygdrive/c/git/jdk/Makefile</code> rather
than <code>C:\git\jdk\Makefile</code>. This rule also applies to input
to the build system, e.g. in arguments to <code>configure</code>. So,
use <code>--with-msvcr-dll=/cygdrive/c/msvcr100.dll</code> rather than
<code>--with-msvcr-dll=c:\msvcr100.dll</code>. For details on this
conversion, see the section on <a href="#fixpath">Fixpath</a>.</p>
<h4 id="locale-requirements">Locale Requirements</h4>
<p>Building and testing the JDK requires a well-defined locale to be
guaranteed to run correctly. On non-Windows operating systems, this is
achieved using the <code>LC_*</code> variables, which propagate to all
child processes of the build. Unfortunately, there is no way to set the
locale for a specific process like this in Windows. Instead, changes to
locale can only be made globally, which will affect all applications run
by the user. Furthermore, Windows makes a difference between user locale
and system locale, where the latter determines e.g. the file path
encoding. Both this locale settings affect building and testing the
JDK.</p>
<p>The <strong>recommended</strong> and <strong>supported</strong> way
of building the JDK on Windows is to set both the system locale and the
user locale to <strong>US English</strong>. The system setting can be
changed by going to the Control Panel, choosing "Regional Settings"
-> "Administrative" and then pressing on the "Change System Locale"
button.</p>
<p>Since this is annoying for users who prefer another locale, we strive
to get the building and testing to work on other locales as well. This
is on a "best effort" level, so beware! You might get odd results in
both building and testing. If you do, remember that locales other than
US English are not supported nor recommended.</p>
<p>It is also imperative to install the US English language pack in
Visual Studio. For details, see <a
href="#microsoft-visual-studio">Microsoft Visual Studio</a>.</p>
<h4 id="cygwin">Cygwin</h4>
<p>Install <a href="https://www.cygwin.com/">Cygwin</a> as instructed on
the home page. It is strongly recommended to use the 64-bit version of
Cygwin.</p>
<p><strong>Note:</strong> Cygwin has a model of continuously updating
all packages without any easy way to install or revert to a specific
version of a package. This means that whenever you add or update a
package in Cygwin, you might (inadvertently) update tools that are used
by the JDK build process, and that can cause unexpected build
problems.</p>
<p>The JDK requires GNU Make 4.0 or greater in Cygwin. This is usually
not a problem, since Cygwin currently only distributes GNU Make at a
version above 4.0.</p>
<p>Apart from the basic Cygwin installation, the following packages must
also be installed:</p>
<ul>
<li><code>autoconf</code></li>
<li><code>make</code></li>
<li><code>zip</code></li>
<li><code>unzip</code></li>
</ul>
<p>Often, you can install these packages using the following command
line:</p>
<pre><code><path to Cygwin setup>/setup-x86_64 -q -P autoconf -P make -P unzip -P zip</code></pre>
<p>Unfortunately, Cygwin can be unreliable in certain circumstances. If
you experience build tool crashes or strange issues when building on
Windows, please check the Cygwin FAQ on the <a
href="https://cygwin.com/faq/faq.html#faq.using.bloda">"BLODA" list</a>
and the section on <a
href="https://cygwin.com/faq/faq.html#faq.using.fixing-fork-failures">fork()
failures</a>.</p>
<h4 id="msys2">MSYS2</h4>
<p>Install <a href="https://www.msys2.org/">MSYS2</a> as instructed on
the home page.</p>
<p>Apart from the basic MSYS2 installation, the following packages must
also be installed:</p>
<ul>
<li><code>autoconf</code></li>
<li><code>tar</code></li>
<li><code>make</code></li>
<li><code>zip</code></li>
<li><code>unzip</code></li>
</ul>
<p>You can install these packages using the following command line:</p>
<pre><code>pacman -S autoconf tar make zip unzip</code></pre>
<h4 id="windows-subsystem-for-linux-wsl">Windows Subsystem for Linux
(WSL)</h4>
<p>WSL comes in two flavors, WSL1 and WSL2. These are drastically
different under the hood. WSL1 runs the binaries natively by translating
Linux kernel calls into Windows kernel calls, while WSL2 runs Linux in a
virtual machine. Both solutions have their pros and cons, and you might
need to test both before deciding which works best for you. Both WSL1
and WSL2 are supported, but to varying degrees.</p>
<p>To use WSL for building the JDK, you will need Windows 10 version
1809 or later, and you will need to install an Ubuntu guest.</p>
<p>It is possible to build both Windows and Linux binaries from WSL. To
build Windows binaries, you must use a Windows boot JDK (located in a
Windows-accessible directory). To build Linux binaries, you must use a
Linux boot JDK. The default behavior is to build for Windows. To build
for Linux, pass
<code>--build=x86_64-unknown-linux-gnu --openjdk-target=x86_64-unknown-linux-gnu</code>
to <code>configure</code>.</p>
<p>If building Windows binaries, the source code must be located in a
Windows- accessible directory. This is because Windows executables (such
as Visual Studio and the boot JDK) must be able to access the source
code. Also, the drive where the source is stored must be mounted as
case-insensitive by changing either /etc/fstab or /etc/wsl.conf in WSL.
Individual directories may be corrected using the fsutil tool in case
the source was cloned before changing the mount options.</p>
<p>Note that while it's possible to build on WSL, testing is still not
fully supported.</p>
<h3 id="macos">macOS</h3>
<p>Apple is using a quite aggressive scheme of pushing OS updates, and
coupling these updates with required updates of Xcode. Unfortunately,
this makes it difficult for a project such as the JDK to keep pace with
a continuously updated machine running macOS. See the section on <a
href="#apple-xcode">Apple Xcode</a> on some strategies to deal with
this.</p>
<p>It is recommended that you use at least macOS 13 (Ventura) and Xcode
14, but earlier versions may also work.</p>
<p>The standard macOS environment contains the basic tooling needed to
build, but for external libraries a package manager is recommended. The
JDK uses <a href="https://brew.sh/">homebrew</a> in the examples, but
feel free to use whatever manager you want (or none).</p>
<h3 id="linux">Linux</h3>
<p>It is often not much problem to build the JDK on Linux. The only
general advice is to try to use the compilers, external libraries and
header files as provided by your distribution.</p>
<p>The basic tooling is provided as part of the core operating system,
but you will most likely need to install developer packages.</p>
<p>For apt-based distributions (Debian, Ubuntu, etc), try this:</p>
<pre><code>sudo apt-get install build-essential</code></pre>
<p>For rpm-based distributions (Fedora, Red Hat, etc), try this:</p>
<pre><code>sudo yum groupinstall "Development Tools"</code></pre>
<p>For Alpine Linux, aside from basic tooling, install the GNU versions
of some programs:</p>
<pre><code>sudo apk add build-base bash grep zip</code></pre>
<h3 id="aix">AIX</h3>
<p>Please consult the AIX section of the <a
href="https://wiki.openjdk.org/display/Build/Supported+Build+Platforms">Supported
Build Platforms</a> OpenJDK Build Wiki page for details about which
versions of AIX are supported.</p>
<h2 id="native-compiler-toolchain-requirements">Native Compiler
(Toolchain) Requirements</h2>
<p>Large portions of the JDK consists of native code, that needs to be
compiled to be able to run on the target platform. In theory, toolchain
and operating system should be independent factors, but in practice
there's more or less a one-to-one correlation between target operating
system and toolchain.</p>
<table>
<thead>
<tr class="header">
<th>Operating system</th>
<th>Supported toolchain</th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td>Linux</td>
<td>gcc, clang</td>
</tr>
<tr class="even">
<td>macOS</td>
<td>Apple Xcode (using clang)</td>
</tr>
<tr class="odd">
<td>AIX</td>
<td>IBM XL C/C++</td>
</tr>
<tr class="even">
<td>Windows</td>
<td>Microsoft Visual Studio</td>
</tr>
</tbody>
</table>
<p>Please see the individual sections on the toolchains for version
recommendations. As a reference, these versions of the toolchains are
used, at the time of writing, by Oracle for the daily builds of the JDK.
It should be possible to compile the JDK with both older and newer
versions, but the closer you stay to this list, the more likely you are
to compile successfully without issues.</p>
<table>
<thead>
<tr class="header">
<th>Operating system</th>
<th>Toolchain version</th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td>Linux</td>
<td>gcc 13.2.0</td>
</tr>
<tr class="even">
<td>macOS</td>
<td>Apple Xcode 14.3.1 (using clang 14.0.3)</td>
</tr>
<tr class="odd">
<td>Windows</td>
<td>Microsoft Visual Studio 2022 version 17.6.5</td>
</tr>
</tbody>
</table>
<p>All compilers are expected to be able to handle the C11 language
standard for C, and C++14 for C++.</p>
<h3 id="gcc">gcc</h3>
<p>The minimum accepted version of gcc is 6.0. Older versions will not
be accepted by <code>configure</code>.</p>
<p>The JDK is currently known to compile successfully with gcc version
13.2 or newer.</p>
<p>In general, any version between these two should be usable.</p>
<h3 id="clang">clang</h3>
<p>The minimum accepted version of clang is 3.5. Older versions will not
be accepted by <code>configure</code>.</p>
<p>To use clang instead of gcc on Linux, use
<code>--with-toolchain-type=clang</code>.</p>
<h3 id="apple-xcode">Apple Xcode</h3>
<p>The oldest supported version of Xcode is 8.</p>
<p>You will need the Xcode command line developer tools to be able to
build the JDK. (Actually, <em>only</em> the command line tools are
needed, not the IDE.) The simplest way to install these is to run:</p>
<pre><code>xcode-select --install</code></pre>
<p>When updating Xcode, it is advisable to keep an older version for
building the JDK. To use a specific version of Xcode you have multiple
options:</p>
<ul>
<li>Use <code>xcode-select -s</code> before running
<code>configure</code>, e.g.
<code>xcode-select -s /Applications/Xcode13.1.app</code>. The drawback
is that the setting is system wide and you may have to revert it after a
JDK build.</li>
<li>Use configure option <code>--with-xcode-path</code>, e.g.
<code>configure --with-xcode-path=/Applications/Xcode13.1.app</code>
This allows using a specific Xcode version for a JDK build,
independently of the active Xcode version by
<code>xcode-select</code>.</li>
</ul>
<p>If you have recently (inadvertently) updated your OS and/or Xcode
version, and the JDK can no longer be built, please see the section on
<a href="#problems-with-the-build-environment">Problems with the Build
Environment</a>, and <a href="#getting-help">Getting Help</a> to find
out if there are any recent, non-merged patches available for this
update.</p>
<h3 id="microsoft-visual-studio">Microsoft Visual Studio</h3>
<p>The minimum accepted version is Visual Studio 2019 version 16.8.
(Note that this version is often presented as "MSVC 14.28", and reported
by cl.exe as 19.28.) Older versions will not be accepted by
<code>configure</code> and will not work. The maximum accepted version
of Visual Studio is 2022.</p>
<p>If you have multiple versions of Visual Studio installed,
<code>configure</code> will by default pick the latest. You can request
a specific version to be used by setting
<code>--with-toolchain-version</code>, e.g.
<code>--with-toolchain-version=2022</code>.</p>
<p>If you have Visual Studio installed but <code>configure</code> fails
to detect it, it may be because of <a href="#spaces-in-path">spaces in
path</a>.</p>
<p>You must install the US English locale, otherwise the build system
might not be able to interact properly with the compiler. You can add
additional language packs when installing Visual Studio.</p>
<p>If you have already installed Visual Studio without the US English
language pack, you can modify the installation to add this. You can
either do this via a GUI like this:</p>
<ul>
<li>Click on "Visual Studio Installer" in Start menu.</li>
<li>Click "Modify".</li>
<li>Select the tab "Language packs".</li>
<li>Choose "English".</li>
<li>Click "Modify".</li>
</ul>
<p>or you can run it on the command line. For this to work, you need to
start <code>cmd.exe</code> using "Run as Administrator". Then execute
the following line: (note that the " characters are essential)</p>
<pre><code>"C:\Program Files (x86)\Microsoft Visual Studio\Installer\vs_installer.exe" modify --channelId VisualStudio.16.Release --productId Microsoft.VisualStudio.Product.BuildTools --addProductLang en-us -p</code></pre>
<p><code>VisualStudio.16.Release</code> represent VS 2019, so adjust the
version number accordingly. If you have not installed the
<code>BuildTools</code>, but e.g. <code>Professional</code>, adjust the
product ID accordingly.</p>
<h3 id="ibm-xl-cc">IBM XL C/C++</h3>
<p>Please consult the AIX section of the <a
href="https://wiki.openjdk.org/display/Build/Supported+Build+Platforms">Supported
Build Platforms</a> OpenJDK Build Wiki page for details about which
versions of XLC are supported.</p>
<h2 id="boot-jdk-requirements">Boot JDK Requirements</h2>
<p>Paradoxically, building the JDK requires a pre-existing JDK. This is
called the "boot JDK". The boot JDK does not, however, have to be a JDK
built directly from the source code available in the OpenJDK Community.
If you are porting the JDK to a new platform, chances are that there
already exists another JDK for that platform that is usable as boot
JDK.</p>
<p>The rule of thumb is that the boot JDK for building JDK major version
<em>N</em> should be a JDK of major version <em>N-1</em>, so for
building JDK 18 a JDK 17 would be suitable as boot JDK. However, the JDK
should be able to "build itself", so an up-to-date build of the current
JDK source is an acceptable alternative. If you are following the
<em>N-1</em> rule, make sure you've got the latest update version, since
e.g. JDK 8 GA might not be able to build JDK 9 on all platforms.</p>
<p>Early in the release cycle, version <em>N-1</em> may not yet have
been released. In that case, the preferred boot JDK will be version
<em>N-2</em> until version <em>N-1</em> is available.</p>
<p>The <code>configure</code> scripts tries to locate a suitable boot
JDK automatically, but due to the lack of standard installation
locations on most platforms, this heuristics has a high likelihood to
fail. If the boot JDK is not automatically detected, or the wrong JDK is
picked, use <code>--with-boot-jdk</code> to point to the JDK to use.</p>
<h3 id="getting-jdk-binaries">Getting JDK Binaries</h3>
<p>An overview of common ways to download and install prebuilt JDK
binaries can be found on https://openjdk.org/install. An alternative is
to download the <a
href="https://www.oracle.com/java/technologies/downloads">Oracle
JDK</a>. Another is <a href="https://adoptium.net/">Adoptium</a>, which
publishes prebuilt binaries for various platforms.</p>
<p>On Linux you can also get a JDK from the Linux distribution. On
apt-based distros (like Debian and Ubuntu),
<code>sudo apt-get install openjdk-<VERSION>-jdk</code> is
typically enough to install a JDK <VERSION>. On rpm-based distros
(like Fedora and Red Hat), try
<code>sudo yum install java-<VERSION>-openjdk-devel</code>.</p>
<h2 id="external-library-requirements">External Library
Requirements</h2>
<p>Different platforms require different external libraries. In general,
libraries are not optional - that is, they are either required or not
used.</p>
<p>If a required library is not detected by <code>configure</code>, you
need to provide the path to it. There are two forms of the
<code>configure</code> arguments to point to an external library:
<code>--with-<LIB>=<path></code> or
<code>--with-<LIB>-include=<path to include> --with-<LIB>-lib=<path to lib></code>.</p>
<p>The first variant is more concise, but require the include files and
library files to reside in a default hierarchy under this directory. In
most cases, it works fine. As a fallback, the second version allows you
to point to the include directory and the lib directory separately.</p>
<h3 id="freetype">FreeType</h3>
<p>FreeType2 from <a href="https://www.freetype.org/">The FreeType
Project</a> is not required on any platform. The exception is on
Unix-based platforms when configuring such that the build artifacts will
reference a system installed library, rather than bundling the JDK's own
copy.</p>
<ul>
<li>To install on an apt-based Linux, try running
<code>sudo apt-get install libfreetype6-dev</code>.</li>
<li>To install on an rpm-based Linux, try running
<code>sudo yum install freetype-devel</code>.</li>
<li>To install on Alpine Linux, try running
<code>sudo apk add freetype-dev</code>.</li>
<li>To install on macOS, try running
<code>brew install freetype</code>.</li>
</ul>
<p>Use <code>--with-freetype-include=<path></code> and
<code>--with-freetype-lib=<path></code> if <code>configure</code>
does not automatically locate the platform FreeType files.</p>
<h3 id="fontconfig">Fontconfig</h3>
<p>Fontconfig from <a href="https://fontconfig.org">freedesktop.org
Fontconfig</a> is required on all platforms except Windows and
macOS.</p>
<ul>
<li>To install on an apt-based Linux, try running
<code>sudo apt-get install libfontconfig-dev</code>.</li>
<li>To install on an rpm-based Linux, try running
<code>sudo yum install fontconfig-devel</code>.</li>
</ul>
<p>Use <code>--with-fontconfig-include=<path></code> and
<code>--with-fontconfig=<path></code> if <code>configure</code>
does not automatically locate the platform Fontconfig files.</p>
<h3 id="cups">CUPS</h3>
<p>CUPS, <a href="https://www.cups.org">Common UNIX Printing System</a>
header files are required on all platforms, except Windows. Often these
files are provided by your operating system.</p>
<ul>
<li>To install on an apt-based Linux, try running
<code>sudo apt-get install libcups2-dev</code>.</li>
<li>To install on an rpm-based Linux, try running
<code>sudo yum install cups-devel</code>.</li>
<li>To install on Alpine Linux, try running
<code>sudo apk add cups-dev</code>.</li>
</ul>
<p>Use <code>--with-cups=<path></code> if <code>configure</code>
does not properly locate your CUPS files.</p>
<h3 id="x11">X11</h3>
<p>Certain <a href="https://www.x.org/">X11</a> libraries and include
files are required on Linux.</p>
<ul>
<li>To install on an apt-based Linux, try running
<code>sudo apt-get install libx11-dev libxext-dev libxrender-dev libxrandr-dev libxtst-dev libxt-dev</code>.</li>
<li>To install on an rpm-based Linux, try running
<code>sudo yum install libXtst-devel libXt-devel libXrender-devel libXrandr-devel libXi-devel</code>.</li>
<li>To install on Alpine Linux, try running
<code>sudo apk add libx11-dev libxext-dev libxrender-dev libxrandr-dev libxtst-dev libxt-dev</code>.</li>
</ul>
<p>Use <code>--with-x=<path></code> if <code>configure</code> does
not properly locate your X11 files.</p>
<h3 id="alsa">ALSA</h3>
<p>ALSA, <a href="https://www.alsa-project.org/">Advanced Linux Sound
Architecture</a> is required on Linux. At least version 0.9.1 of ALSA is
required.</p>
<ul>
<li>To install on an apt-based Linux, try running
<code>sudo apt-get install libasound2-dev</code>.</li>
<li>To install on an rpm-based Linux, try running
<code>sudo yum install alsa-lib-devel</code>.</li>
<li>To install on Alpine Linux, try running
<code>sudo apk add alsa-lib-dev</code>.</li>
</ul>
<p>Use <code>--with-alsa=<path></code> if <code>configure</code>
does not properly locate your ALSA files.</p>
<h3 id="libffi">libffi</h3>
<p>libffi, the <a href="https://sourceware.org/libffi">Portable Foreign
Function Interface Library</a> is required when building the Zero
version of Hotspot.</p>
<ul>
<li>To install on an apt-based Linux, try running
<code>sudo apt-get install libffi-dev</code>.</li>
<li>To install on an rpm-based Linux, try running
<code>sudo yum install libffi-devel</code>.</li>
<li>To install on Alpine Linux, try running
<code>sudo apk add libffi-dev</code>.</li>
</ul>
<p>Use <code>--with-libffi=<path></code> if <code>configure</code>
does not properly locate your libffi files.</p>
<h2 id="build-tools-requirements">Build Tools Requirements</h2>
<h3 id="autoconf">Autoconf</h3>
<p>The JDK build requires <a
href="https://www.gnu.org/software/autoconf">Autoconf</a> on all
platforms. At least version 2.69 is required.</p>
<ul>
<li>To install on an apt-based Linux, try running
<code>sudo apt-get install autoconf</code>.</li>
<li>To install on an rpm-based Linux, try running
<code>sudo yum install autoconf</code>.</li>
<li>To install on Alpine Linux, try running
<code>sudo apk add autoconf</code>.</li>
<li>To install on macOS, try running
<code>brew install autoconf</code>.</li>
<li>To install on Windows, try running
<code><path to Cygwin setup>/setup-x86_64 -q -P autoconf</code>.</li>
</ul>
<p>If <code>configure</code> has problems locating your installation of
autoconf, you can specify it using the <code>AUTOCONF</code> environment
variable, like this:</p>
<pre><code>AUTOCONF=<path to autoconf> configure ...</code></pre>
<h3 id="gnu-make">GNU Make</h3>
<p>The JDK build requires <a
href="https://www.gnu.org/software/make">GNU Make</a>. No other flavors
of make are supported.</p>
<p>At least version 3.81 of GNU Make must be used. For distributions
supporting GNU Make 4.0 or above, we strongly recommend it. GNU Make 4.0
contains useful functionality to handle parallel building (supported by
<code>--with-output-sync</code>) and speed and stability
improvements.</p>
<p>Note that <code>configure</code> locates and verifies a properly
functioning version of <code>make</code> and stores the path to this
<code>make</code> binary in the configuration. If you start a build
using <code>make</code> on the command line, you will be using the
version of make found first in your <code>PATH</code>, and not
necessarily the one stored in the configuration. This initial make will
be used as "bootstrap make", and in a second stage, the make located by
<code>configure</code> will be called. Normally, this will present no
issues, but if you have a very old <code>make</code>, or a non-GNU Make
<code>make</code> in your path, this might cause issues.</p>
<p>If you want to override the default make found by
<code>configure</code>, use the <code>MAKE</code> configure variable,
e.g. <code>configure MAKE=/opt/gnu/make</code>.</p>
<h3 id="gnu-bash">GNU Bash</h3>
<p>The JDK build requires <a
href="https://www.gnu.org/software/bash">GNU Bash</a>. No other shells
are supported.</p>
<p>At least version 3.2 of GNU Bash must be used.</p>
<h2 id="running-configure">Running Configure</h2>
<p>To build the JDK, you need a "configuration", which consists of a
directory where to store the build output, coupled with information
about the platform, the specific build machine, and choices that affect
how the JDK is built.</p>
<p>The configuration is created by the <code>configure</code> script.
The basic invocation of the <code>configure</code> script looks like
this:</p>
<pre><code>bash configure [options]</code></pre>
<p>This will create an output directory containing the configuration and
setup an area for the build result. This directory typically looks like
<code>build/linux-x64-server-release</code>, but the actual name depends
on your specific configuration. (It can also be set directly, see <a
href="#using-multiple-configurations">Using Multiple
Configurations</a>). This directory is referred to as
<code>$BUILD</code> in this documentation.</p>
<p><code>configure</code> will try to figure out what system you are
running on and where all necessary build components are. If you have all
prerequisites for building installed, it should find everything. If it
fails to detect any component automatically, it will exit and inform you
about the problem.</p>
<p>Some command line examples:</p>
<ul>
<li><p>Create a 32-bit build for Windows with FreeType2 in
<code>C:\freetype-i586</code>:</p>
<pre><code>bash configure --with-freetype=/cygdrive/c/freetype-i586 --with-target-bits=32</code></pre></li>
<li><p>Create a debug build with the <code>server</code> JVM and DTrace
enabled:</p>
<pre><code>bash configure --enable-debug --with-jvm-variants=server --enable-dtrace</code></pre></li>
</ul>
<h3 id="common-configure-arguments">Common Configure Arguments</h3>
<p>Here follows some of the most common and important
<code>configure</code> argument.</p>
<p>To get up-to-date information on <em>all</em> available
<code>configure</code> argument, please run:</p>
<pre><code>bash configure --help</code></pre>
<p>(Note that this help text also include general autoconf options, like
<code>--dvidir</code>, that is not relevant to the JDK. To list only
JDK-specific features, use <code>bash configure --help=short</code>
instead.)</p>
<h4 id="configure-arguments-for-tailoring-the-build">Configure Arguments
for Tailoring the Build</h4>
<ul>
<li><code>--enable-debug</code> - Set the debug level to
<code>fastdebug</code> (this is a shorthand for
<code>--with-debug-level=fastdebug</code>)</li>
<li><code>--with-debug-level=<level></code> - Set the debug level,
which can be <code>release</code>, <code>fastdebug</code>,
<code>slowdebug</code> or <code>optimized</code>. Default is
<code>release</code>. <code>optimized</code> is variant of
<code>release</code> with additional Hotspot debug code.</li>
<li><code>--with-native-debug-symbols=<method></code> - Specify if
and how native debug symbols should be built. Available methods are
<code>none</code>, <code>internal</code>, <code>external</code>,
<code>zipped</code>. Default behavior depends on platform. See <a
href="#native-debug-symbols">Native Debug Symbols</a> for more
details.</li>
<li><code>--with-version-string=<string></code> - Specify the
version string this build will be identified with.</li>
<li><code>--with-version-<part>=<value></code> - A group of
options, where <code><part></code> can be any of <code>pre</code>,
<code>opt</code>, <code>build</code>, <code>major</code>,
<code>minor</code>, <code>security</code> or <code>patch</code>. Use
these options to modify just the corresponding part of the version
string from the default, or the value provided by
<code>--with-version-string</code>.</li>
<li><code>--with-jvm-variants=<variant>[,<variant>...]</code>
- Build the specified variant (or variants) of Hotspot. Valid variants
are: <code>server</code>, <code>client</code>, <code>minimal</code>,
<code>core</code>, <code>zero</code>, <code>custom</code>. Note that not
all variants are possible to combine in a single build.</li>
<li><code>--enable-jvm-feature-<feature></code> or
<code>--disable-jvm-feature-<feature></code> - Include (or
exclude) <code><feature></code> as a JVM feature in Hotspot. You
can also specify a list of features to be enabled, separated by space or
comma, as
<code>--with-jvm-features=<feature>[,<feature>...]</code>.
If you prefix <code><feature></code> with a <code>-</code>, it
will be disabled. These options will modify the default list of features
for the JVM variant(s) you are building. For the <code>custom</code> JVM
variant, the default list is empty. A complete list of valid JVM
features can be found using <code>bash configure --help</code>.</li>
<li><code>--with-target-bits=<bits></code> - Create a target
binary suitable for running on a <code><bits></code> platform. Use
this to create 32-bit output on a 64-bit build platform, instead of
doing a full cross-compile. (This is known as a <em>reduced</em>
build.)</li>
</ul>
<p>On Linux, BSD and AIX, it is possible to override where Java by
default searches for runtime/JNI libraries. This can be useful in
situations where there is a special shared directory for system JNI
libraries. This setting can in turn be overridden at runtime by setting
the <code>java.library.path</code> property.</p>
<ul>
<li><code>--with-jni-libpath=<path></code> - Use the specified
path as a default when searching for runtime libraries.</li>
</ul>
<h4 id="configure-arguments-for-native-compilation">Configure Arguments
for Native Compilation</h4>
<ul>
<li><code>--with-devkit=<path></code> - Use this devkit for
compilers, tools and resources</li>
<li><code>--with-sysroot=<path></code> - Use this directory as
sysroot</li>
<li><code>--with-extra-path=<path>[;<path>]</code> - Prepend
these directories to the default path when searching for all kinds of
binaries</li>
<li><code>--with-toolchain-path=<path>[;<path>]</code> -
Prepend these directories when searching for toolchain binaries
(compilers etc)</li>
<li><code>--with-extra-cflags=<flags></code> - Append these flags
when compiling JDK C files</li>
<li><code>--with-extra-cxxflags=<flags></code> - Append these
flags when compiling JDK C++ files</li>
<li><code>--with-extra-ldflags=<flags></code> - Append these flags
when linking JDK libraries</li>
</ul>
<h4 id="configure-arguments-for-external-dependencies">Configure
Arguments for External Dependencies</h4>
<ul>
<li><code>--with-boot-jdk=<path></code> - Set the path to the <a
href="#boot-jdk-requirements">Boot JDK</a></li>
<li><code>--with-freetype=<path></code> - Set the path to <a
href="#freetype">FreeType</a></li>
<li><code>--with-cups=<path></code> - Set the path to <a
href="#cups">CUPS</a></li>
<li><code>--with-x=<path></code> - Set the path to <a
href="#x11">X11</a></li>
<li><code>--with-alsa=<path></code> - Set the path to <a
href="#alsa">ALSA</a></li>
<li><code>--with-libffi=<path></code> - Set the path to <a
href="#libffi">libffi</a></li>
<li><code>--with-jtreg=<path></code> - Set the path to JTReg. See
<a href="#running-tests">Running Tests</a></li>
</ul>
<p>Certain third-party libraries used by the JDK (libjpeg, giflib,
libpng, lcms and zlib) are included in the JDK repository. The default
behavior of the JDK build is to use the included ("bundled") versions of