Mac 编译jdk源码小记

编译的是jdk15，需要安装一个jdk14来作为bootstrap JDK，源码编译要求的bootstrap jdk 版本最少14，15

第一步：下载jdk源码

没有使用hg去下载，使用了git仓库代码 https://github.com/openjdk/jdk.git

克隆仓库代码

git clone https://github.com/unofficial-openjdk/openjdk.git

　创建本地分支，以防修改坏代码

cd openjdk && git checkout -b build

第二步：环境准备，安装xcode，可以不安装，只安装Xcode command lines ，这里为了省事，直接安装xcode

安装 FreeType，使用brew安装

安装 Autoconf，使用brew安装 brew install autoconf

第三步：生成config

bash configure --enable-debug --with-jvm-variants=server --enable-dtrace

看到生成configuration successful 即可

第四步：编译

make jdk

第五步：查看编译的jdk

cd build/macosx-x86_64-server-fastdebug/jdk
# 查看版本
./bin/java -version

看到输出结果即可完成编译。

以下为英文编译原文，供参考：

If you are eager to try out building the JDK, 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 JDK repository that you want to build.

Get the complete source code: \ hg clone http://hg.openjdk.java.net/jdk/jdk
Run configure: \ bash configure

If configure fails due to missing dependencies (to either the toolchain, [build tools](

build-tools-requirements), [external libraries](

external-library-requirements) 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.
Run make: \ make images
Verify your newly built JDK: \ ./build/*/images/jdk/bin/java -version
Run basic tests: \ make run-test-tier1

If any of these steps failed, or if you want to know more about build requirements or build functionality, please continue reading this document.

Introduction

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.

If you just want to use the JDK and not build it yourself, this document is not for you. See for instance OpenJDK installation for some methods of installing a prebuilt JDK.

Getting the Source Code

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 repositories. 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.

Special Considerations

For a smooth building experience, it is recommended that you follow these rules on where and how to check out the source code.
- 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.
- 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.
- 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.
- On Windows, if using Cygwin, extra care must be taken to make sure the environment is consistent. It is recommended that you follow this procedure:
  - Create the directory that is going to contain the top directory of the JDK clone by using the mkdir command in the Cygwin bash shell. That is, do not create it using Windows Explorer. This will ensure that it will have proper Cygwin attributes, and that it's children will inherit those attributes.
  - 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.
  - Clone the JDK repository using the Cygwin command line hg client as instructed in this document. That is, do not use another Mercurial client such as TortoiseHg.
  Failure to follow this procedure might result in hard-to-debug build problems.
Build Hardware Requirements

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.

We strongly recommend usage of an SSD disk for the build, since disk speed is one of the limiting factors for build performance.

Building on x86

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.

Even for 32-bit builds, it is recommended to use a 64-bit build machine, and instead create a 32-bit target using --with-target-bits=32.

Building on aarch64

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.

If you do not have access to sufficiently powerful hardware, it is also possible to use cross-compiling.

Building on 32-bit arm

This is not recommended. Instead, see the section on [Cross-compiling](

cross-compiling).

Operating System Requirements

The mainline JDK project supports Linux, macOS, AIX and Windows. Support for other operating system, e.g. BSD, exists in separate "port" projects.

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.

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.

Operating system Vendor/version used

Linux Oracle Enterprise Linux 6.4 / 7.6 macOS Mac OS X 10.13 (High Sierra) Windows Windows Server 2012 R2

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.

The Build Group has a wiki page with Supported Build Platforms. From time to time, this is updated by contributors to list successes or failures of building on different platforms.

Windows

Windows XP is not a supported platform, but all newer Windows should be able to build the JDK.

On Windows, it is important that you pay attention to the instructions in the Special Considerations.

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 only supported such layers are Cygwin and Windows Subsystem for Linux (WSL). (Msys is no longer supported due to a too old bash; msys2 would likely be possible to support in a future version but that would require effort to implement.)

Internally in the build system, all paths are represented as Unix-style paths, e.g. /cygdrive/c/hg/jdk9/Makefile rather than C:\hg\jdk9\Makefile. This rule also applies to input to the build system, e.g. in arguments to configure. So, use --with-msvcr-dll=/cygdrive/c/msvcr100.dll rather than --with-msvcr-dll=c:\msvcr100.dll. For details on this conversion, see the section on Fixpath.

Cygwin

A functioning Cygwin environment is required for building the JDK on Windows. If you have a 64-bit OS, we strongly recommend using the 64-bit version of Cygwin.

Note: 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.

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.

Apart from the basic Cygwin installation, the following packages must also be installed:
- autoconf
- make
- zip
- unzip
  
  Often, you can install these packages using the following command line:
```
<path to Cygwin setup>/setup-x86_64 -q -P autoconf -P make -P unzip -P zip
```
```
sudo apt-get install build-essential
```
```
sudo yum groupinstall "Development Tools"
```
```
xcode-select --install
```
```
AUTOCONF=<path to autoconf> configure ...
```
```
bash configure [options]
```
  - Create a 32-bit build for Windows with FreeType2 in C:\freetype-i586:
```
bash configure --with-freetype=/cygdrive/c/freetype-i586 --with-target-bits=32
```
  - Create a debug build with the server JVM and DTrace enabled:
```
bash configure --enable-debug --with-jvm-variants=server --enable-dtrace
```
```
bash configure --help
```
    - JOBS - Specify the number of jobs to build with. See Build Performance.
    - LOG - Specify the logging level and functionality. See Checking the Build Log File
    - CONF and CONF_NAME - Selecting the configuration(s) to use. See Using Multiple Configurations
      
      Test Make Control Variables
      
      These make control variables only make sense when running tests. Please see Testing the JDK for details.
      - TEST
      - TEST_JOBS
      - JTREG
      - GTEST
        
        Advanced Make Control Variables
        
        These advanced make control variables can be potentially unsafe. See Hints and Suggestions for Advanced Users and Understanding the Build System for details.
        
        SPEC
        
        CONF_CHECK
        
        COMPARE_BUILD
        
        JDK_FILTER
        
        SPEC_FILTER
        
        Running Tests
        
        Most of the JDK tests are using the JTReg test framework. Make sure that your configuration knows where to find your installation of JTReg. If this is not picked up automatically, use the --with-jtreg=<path to jtreg home> option to point to the JTReg framework. Note that this option should point to the JTReg home, i.e. the top directory, containing lib/jtreg.jar etc.
        
        The Adoption Group provides recent builds of jtreg here. Download the latest .tar.gz file, unpack it, and point --with-jtreg to the jtreg directory that you just unpacked.
        
        Building of Hotspot Gtest suite requires the source code of Google Test framework. The top directory, which contains both googletest and googlemock directories, should be specified via --with-gtest. The supported version of Google Test is 1.8.1, whose source code can be obtained:
        
        by downloading and unpacking the source bundle from here
        
        or by checking out release-1.8.1 tag of googletest project: git clone -b release-1.8.1 https://github.com/google/googletest
        
        To execute the most basic tests (tier 1), use:
        
        make run-test-tier1
        
        bash configure --with-devkit=<devkit-path> --openjdk-target=ppc64-linux-gnu && make
        
        make [ TARGETS="<TARGET_TRIPLET>+" ] [ BASE_OS=<OS> ] [ BASE_OS_VERSION=<VER> ]
        
        cd make/devkit
        make TARGETS="ppc64le-linux-gnu aarch64-linux-gnu" BASE_OS=Fedora BASE_OS_VERSION=21
        ls -1 ../../build/devkit/result/
        x86_64-linux-gnu-to-aarch64-linux-gnu
        x86_64-linux-gnu-to-ppc64le-linux-gnu
        
        cd /tools/gcc-linaro-arm-linux-gnueabihf-raspbian-2012.09-20120921_linux/arm-linux-gnueabihf/libc
        dpkg-deb -x /tmp/libasound2_1.0.25-4_armhf.deb .
        dpkg-deb -x /tmp/libasound2-dev_1.0.25-4_armhf.deb .
        
        apt install g++-aarch64-linux-gnu gcc-aarch64-linux-gnu
        
        sudo qemu-debootstrap --arch=arm64 --verbose \
        --include=fakeroot,build-essential,libx11-dev,libxext-dev,libxrender-dev,libxrandr-dev,libxtst-dev,libxt-dev,libcups2-dev,libfontconfig1-dev,libasound2-dev,libfreetype6-dev,libpng12-dev \
        --resolve-deps jessie /chroots/arm64 http://httpredir.debian.org/debian/
        
        CC=aarch64-linux-gnu-gcc CXX=aarch64-linux-gnu-g++ sh ./configure --openjdk-target=aarch64-linux-gnu --with-sysroot=/chroots/arm64/ --with-toolchain-path=/chroots/arm64/
        make images
        ls build/linux-aarch64-normal-server-release/
        
        --with-num-cores -- number of cores in the build system, e.g. --with-num-cores=8.
        
        --with-memory-size -- memory (in MB) available in the build system, e.g. --with-memory-size=1024
        
        You can also specify directly the number of build jobs to use with --with-jobs=N to configure, or JOBS=N to make. Do not use the -j flag to make. In most cases it will be ignored by the makefiles, but it can cause problems for some make targets.
        
        It might also be necessary to specify the JVM arguments passed to the Boot JDK, using e.g. --with-boot-jdk-jvmargs="-Xmx8G". Doing so will override the default JVM arguments passed to the Boot JDK.
        
        At the end of a successful execution of configure, you will get a performance summary, indicating how well the build will perform. Here you will also get performance hints. If you want to build fast, pay attention to those!
        
        If you want to tweak build performance, run with make LOG=info to get a build time summary at the end of the build process.
        
        Disk Speed
        
        If you are using network shares, e.g. via NFS, for your source code, make sure the build directory is situated on local disk (e.g. by ln -s /localdisk/jdk-build $JDK-SHARE/build). The performance penalty is extremely high for building on a network share; close to unusable.
        
        Also, make sure that your build tools (including Boot JDK and toolchain) is located on a local disk and not a network share.
        
        As has been stressed elsewhere, do use SSD for source code and build directory, as well as (if possible) the build tools.
        
        Virus Checking
        
        The use of virus checking software, especially on Windows, can significantly slow down building of the JDK. If possible, turn off such software, or exclude the directory containing the JDK source code from on-the-fly checking.
        
        Ccache
        
        The JDK build supports building with ccache when using gcc or clang. Using ccache can radically speed up compilation of native code if you often rebuild the same sources. Your milage may vary however, so we recommend evaluating it for yourself. To enable it, make sure it's on the path and configure with --enable-ccache.
        
        Precompiled Headers
        
        By default, the Hotspot build uses preccompiled headers (PCH) on the toolchains were it is properly supported (clang, gcc, and Visual Studio). Normally, this speeds up the build process, but in some circumstances, it can actually slow things down.
        
        You can experiment by disabling precompiled headers using --disable-precompiled-headers.
        
        Icecc / icecream
        
        icecc/icecream is a simple way to setup a distributed compiler network. If you have multiple machines available for building the JDK, you can drastically cut individual build times by utilizing it.
        
        To use, setup an icecc network, and install icecc on the build machine. Then run configure using --enable-icecc.
        
        Using sjavac
        
        To speed up Java compilation, especially incremental compilations, you can try the experimental sjavac compiler by using --enable-sjavac.
        
        Building the Right Target
        
        Selecting the proper target to build can have dramatic impact on build time. For normal usage, jdk or the default target is just fine. You only need to build images for shipping, or if your tests require it.
        
        See also Using Fine-Grained Make Targets on how to build an even smaller subset of the product.
        
        Troubleshooting
        
        If your build fails, it can sometimes be difficult to pinpoint the problem or find a proper solution.
        
        Locating the Source of the Error
        
        When a build fails, it can be hard to pinpoint the actual cause of the error. In a typical build process, different parts of the product build in parallel, with the output interlaced.
        
        Build Failure Summary
        
        To help you, the build system will print a failure summary at the end. It looks like this:
        
        ERROR: Build failed for target 'hotspot' in configuration 'linux-x64' (exit code 2)
        
        === Output from failing command(s) repeated here ===
        * For target hotspot_variant-server_libjvm_objs_psMemoryPool.o:
        /localhome/hg/jdk9-sandbox/hotspot/src/share/vm/services/psMemoryPool.cpp:1:1: error: 'failhere' does not name a type
        ... (rest of output omitted)
        
        * All command lines available in /localhome/hg/jdk9-sandbox/build/linux-x64/make-support/failure-logs.
        === End of repeated output ===
        
        === Make failed targets repeated here ===
        lib/CompileJvm.gmk:207: recipe for target '/localhome/hg/jdk9-sandbox/build/linux-x64/hotspot/variant-server/libjvm/objs/psMemoryPool.o' failed
        make/Main.gmk:263: recipe for target 'hotspot-server-libs' failed
        === End of repeated output ===
        
        Hint: Try searching the build log for the name of the first failed target.
        Hint: If caused by a warning, try configure --disable-warnings-as-errors.
        
        File 'xxx' has modification time in the future.
        Clock skew detected. Your build may be incomplete.
        
        fatal error - couldn't allocate heap
        cannot create ... Permission denied
        spawn failed
        
        cd ~
        mkdir hg-ext
        cd hg-ext
        hg clone http://hg.openjdk.java.net/code-tools/defpath
        cat << EOT >> ~/.hgrc
        [extensions]
        defpath=~/hg-ext/defpath/defpath.py
        EOT
        
        hg defpath -d -u <your OpenJDK username>
        
        cat << EOT > /tmp/configure
        #!/bin/bash
        if [ \$(pwd) = \$(cd \$(dirname \$0); pwd) ] ; then
        echo >&2 "Abort: Trying to call configure helper recursively"
        exit 1
        fi
        
        bash \$PWD/configure "\$@"
        EOT
        chmod +x /tmp/configure
        sudo mv /tmp/configure /usr/local/bin
        
        Note that if used incorrectly, this can lead to a broken build!
        
        To achieve this, append -only to the build target. For instance, make jdk.jdwp.agent-java-only will only build the java phase of the jdk.jdwp.agent module. If the required dependencies are not present, the build can fail. On the other hand, the execution time measures in milliseconds.
        
        A useful pattern is to build the first time normally (e.g. make jdk.jdwp.agent) and then on subsequent builds, use the -only make target.
        
        Rebuilding Part of java.base (JDK_FILTER)
        
        If you are modifying files in java.base, which is the by far largest module in the JDK, then you need to rebuild all those files whenever a single file has changed. (This inefficiency will hopefully be addressed in JDK 10.)
        
        As a hack, you can use the make control variable JDK_FILTER to specify a pattern that will be used to limit the set of files being recompiled. For instance, make java.base JDK_FILTER=javax/crypto (or, to combine methods, make java.base-java-only JDK_FILTER=javax/crypto) will limit the compilation to files in the javax.crypto package.
        
        Learn About Mercurial
        
        To become an efficient JDK developer, it is recommended that you invest in learning Mercurial properly. Here are some links that can get you started:
        
        Mercurial for git users
        
        The official Mercurial tutorial
        
        hg init
        
        Mercurial: The Definitive Guide
        
        Understanding the Build System
        
        This section will give you a more technical description on the details of the build system.
        
        Configurations
        
        The build system expects to find one or more configuration. These are technically defined by the spec.gmk in a subdirectory to the build subdirectory. The spec.gmk file is generated by configure, and contains in principle the configuration (directly or by files included by spec.gmk).
        
        You can, in fact, select a configuration to build by pointing to the spec.gmk file with the SPEC make control variable, e.g. make SPEC=$BUILD/spec.gmk. While this is not the recommended way to call make as a user, it is what is used under the hood by the build system.
        
        Build Output Structure
        
        The build output for a configuration will end up in build/<configuration name>, which we refer to as $BUILD in this document. The $BUILD directory contains the following important directories:
        
        buildtools/
        configure-support/
        hotspot/
        images/
        jdk/
        make-support/
        support/
        test-results/
        test-support/
        
        $(eval $(call SetupJavaCompilation, BUILD_FOO_CLASSES, \
        SETUP := GENERATE_OLDBYTECODE, \
        SRC := $(TOPDIR)/src/jkd.foo/share/classes, \
        INCLUDES := jdk/internal/foo, \
        BIN := $(SUPPORT_OUTPUTDIR)/foo_classes, \
        ))
        
        make COMPARE_BUILD=CONF=--enable-new-hotspot-feature:MAKE=hotspot
        
        '<style type="text/css">pre, code, tt { color: #1d6ae5; }</style>'
        
        header-includes:
        
        Override styles from the base CSS file that are not ideal for this document.
        
        If this seems overwhelming to you, the Adoption Group is there to help you! A good place to start is their 'New Contributor' page, or start reading the comprehensive Getting Started Kit. The Adoption Group will also happily answer any questions you have about contributing. Contact them by mail or IRC.
        
        The official place to start is the 'How to contribute' page. There is also an official (but somewhat outdated and skimpy on details) Developer's Guide.
        
        First of all: Thank you! We gladly welcome your contribution. However, please bear in mind that the JDK is a massive project, and we must ask you to follow our rules and guidelines to be able to accept your contribution.
        
        So, now you've built your JDK, and made your first patch, and want to contribute it back to the OpenJDK Community.
        
        Contributing to the JDK
        
        Please check that you adhere to the Code Conventions for the Build System before submitting patches.
        
        To analyze build performance, run with LOG=trace and check $BUILD/build-trace-time.log. Use JOBS=1 to avoid parallelism.
        
        See make/InitSupport.gmk for details on how to use COMPARE_BUILD.
        
        To automatically build two consecutive versions and compare them, use COMPARE_BUILD. The value of COMPARE_BUILD is a set of variable=value assignments, like this:
        
        To compare the output of two different builds and see if, and how, they differ, run $BUILD1/compare.sh -o $BUILD2, where $BUILD1 and $BUILD2 are the two builds you want to compare.
        
        To test for/debug race conditions, try running make JOBS=1 and make JOBS=100 and see if it makes any difference. (It shouldn't).
        
        Correct dependency tracking is paramount. Sloppy dependency tracking will lead to improper parallelization, or worse, race conditions.
        
        By encapsulating and expressing the high-level knowledge of what should be done, rather than how it should be done (as is normal in Makefiles), we can build a much more powerful and flexible build system.
        
        While technically using make, the make source files of the JDK does not resemble most other Makefiles. Instead of listing specific targets and actions (perhaps using patterns), the basic modus operandi is to call a high-level function (or properly, macro) from the API in make/common. For instance, to compile all classes in the jdk.internal.foo package in the jdk.foo module, a call like this would be made:
        
        This section contains a few remarks about how to develop for the build system itself. It is not relevant if you are only making changes in the product source code.
        
        Developing the Build System Itself
        
        In previous versions of the JDK, the generated script was checked in at make/autoconf/generated-configure.sh. This is no longer the case.
        
        The build system will detect if the Autoconf source files have changed, and will trigger a regeneration of the generated script if needed. You can also manually request such an update by bash configure autogen.
        
        The configure script in the top level directory of the JDK is just a thin wrapper that calls make/autoconf/configure. This in turn will run autoconf to create the runnable (generated) configure script, as .build/generated-configure.sh. Apart from being responsible for the generation of the runnable script, the configure script also provides functionality that is not easily expressed in the normal Autoconf framework. As part of this functionality, the generated script is called.
        
        The configure script is based on the autoconf framework, but in some details deviate from a normal autoconf configure script.
        
        Autoconf Details
        
        When building for distribution, zipped is a good solution. Binaries built with internal is suitable for use by developers, since they facilitate debugging, but should be stripped before distributed to end users.
        
        none means that no debug symbols will be generated during the build.
        
        internal means that debug symbols will be generated during the build, and they will be stored in the generated binary.
        
        external means that debug symbols will be generated during the build, and after the compilation, they will be moved into a separate .debuginfo file. (This was previously known as FDS, Full Debug Symbols).
        
        zipped is like external, but the .debuginfo file will also be zipped into a .diz file.
        
        The JDK supports different methods on how to handle debug symbols. The method used is selected by --with-native-debug-symbols, and available methods are none, internal, external, zipped.
        
        Native libraries and executables can have debug symbol (and other debug information) associated with them. How this works is very much platform dependent, but a common problem is that debug symbol information takes a lot of disk space, but is rarely needed by the end user.
        
        Native Debug Symbols
        
        This conversion is done by the fixpath tool, which is a small wrapper that modifies unix-style paths to Windows-style paths in command lines. Fixpath is compiled automatically by configure.
        
        In the JDK build, we always use Unix paths internally, and only just before calling a tool that does not understand Unix paths do we convert them to Windows paths.
        
        Windows path typically look like C:\User\foo, while Unix paths look like /home/foo. Tools with roots from Unix often experience issues related to this mismatch when running on Windows.
        
        Fixpath
        
        images: This is the directory were the output of the *-image make targets end up. For instance, make jdk-image ends up in images/jdk.
        
        jdk: This is the "exploded image". After make jdk, you will be able to launch the newly built JDK by running $BUILD/jdk/bin/java.
        
        test-results: This directory contains the results from running tests.
        
        support: This is an area for intermediate files needed during the build, e.g. generated source code, object files and class files. Some noteworthy directories in support is gensrc, which contains the generated source code, and the modules_* directories, which contains the files in a per-module hierarchy that will later be collapsed into the jdk directory of the exploded image.
        
        buildtools: This is an area for tools compiled for the build platform that are used during the rest of the build.
        
        hotspot: This is an area for intermediate files needed when building hotspot.
        
        configure-support, make-support and test-support: These directories contain files that are needed by the build system for configure, make and for running tests.
        
        This is what they are used for:
        
        When using an iterative development style with frequent quick rebuilds, the dependency check made by make can take up a significant portion of the time spent on the rebuild. In such cases, it can be useful to bypass the dependency check in make.
        
        Skipping the Dependency Check
        
        Note that some phases may depend on others, e.g. java depends on gensrc (if present). Make will build all needed prerequisites before building the requested phase.
        
        You can build only a single phase for a module by using the notation $MODULE-$PHASE. For instance, to build the gensrc phase for java.base, use make java.base-gensrc.
        
        gensrc (Generate source code to compile)
        
        gendata (Generate non-source code artifacts)
        
        copy (Copy resource artifacts)
        
        java (Compile Java code)
        
        launchers (Compile native executables)
        
        libs (Compile native libraries)
        
        The build process for each module is divided into separate phases. Not all modules need all phases. Which are needed depends on what kind of source code and other artifact the module consists of. The phases are:
        
        Building Individual Module Phases
        
        You can also specify a set of modules, just as you can always specify a set of make targets: make jdk.crypto.cryptoki jdk.crypto.ec jdk.crypto.mscapi
        
        The safe way to use fine-grained make targets is to use the module specific make targets. All source code in the JDK is organized so it belongs to a module, e.g. java.base or jdk.jdwp.agent. You can build only a specific module, by giving it as make target: make jdk.jdwp.agent. If the specified module depends on other modules (e.g. java.base), those modules will be built first.
        
        Building Individual Modules
        
        If you are prepared to take some risk of an incorrect build, and know enough of the system to understand how things build and interact, you can speed up the build process considerably by instructing make to only build a portion of the product.
        
        The default behavior for make is to create consistent and correct output, at the expense of build speed, if necessary.
        
        Using Fine-Grained Make Targets
        
        From time to time, you will also need to modify the command line to configure due to changes. Use make print-configure to show the command line used for your current configuration.
        
        You can also use CONF_CHECK=ignore to skip the check for a needed configure update. This might speed up the build, but comes at the risk of an incorrect build result. This is only recommended if you know what you're doing.
        
        Most of the time, you will be fine by running configure again with the same arguments as the last time, which can easily be performed by make reconfigure. To simplify this, you can use the CONF_CHECK make control variable, either as make CONF_CHECK=auto, or by setting an environment variable. For instance, if you add export CONF_CHECK=auto to your .bashrc file, make will always run reconfigure automatically whenever the configure script has changed.
        
        If you update the repository and part of the configure script has changed, the build system will force you to re-run configure.
        
        Handling Reconfigurations
        
        Then you can build that configuration using make CONF_NAME=<name> or make CONF=<pattern>, where <pattern> is a substring matching one or several configurations, e.g. CONF=debug. The special empty pattern (CONF=) will match all available configuration, so make CONF= hotspot will build the hotspot target for all configurations. Alternatively, you can execute make in the configuration directory, e.g. cd build/<name> && make.
        
        You can have multiple configurations for a single source repository. When you create a new configuration, run configure --with-conf-name=<name> to create a configuration with the name <name>. Alternatively, you can create a directory under build and run configure from there, e.g. mkdir build/<name> && cd build/<name> && bash ../../configure.
        
        Using Multiple Configurations
        
        Now configure --en<tab>-dt<tab> will result in configure --enable-dtrace.
        
        The configure script can get completion for options, but for this to work you need to help bash on the way. The standard way of running the script, bash configure, will not be understood by bash completion. You need configure to be the command to run. One way to achieve this is to add a simple helper script to your path:
        
        Make completion will work out of the box, and will complete valid make targets. For instance, typing make jdk-i<tab> will complete to make jdk-image.
        
        The configure and make commands tries to play nice with bash command-line completion (using <tab> or <tab><tab>). To use this functionality, make sure you enable completion in your ~/.bashrc (see instructions for bash in your operating system).
        
        Bash Completion
        
        You can now setup a proper push path using:
        
        Install the extension by cloning http://hg.openjdk.java.net/code-tools/defpath and updating your .hgrc file. Here's one way to do this:
        
        To help you prepare a proper push path for a Mercurial repository, there exists a useful tool known as defpath. It will help you setup a proper push path for pushing changes to the JDK.
        
        Setting Up a Repository for Pushing Changes (defpath)
        
        Hints and Suggestions for Advanced Users
        
        contributing-to-openjdk) for more information.
        
        If you need general help or advice about developing for the JDK, you can also contact the Adoption Group. See the section on [Contributing to OpenJDK](
        
        If none of the suggestions in this document helps you, or if you find what you believe is a bug in the build system, please contact the Build Group by sending a mail to build-dev@openjdk.java.net. Please include the relevant parts of the configure and/or build log.
        
        Getting Help
        
        This can be a sign of a Cygwin problem. See the information about solving problems in the Cygwin section. Rebooting the computer might help temporarily.
        
        On Windows, you might get error messages like this:
        
        Out of Memory Errors
        
        If you see these warnings, reset the clock on the build machine, run make clean and restart the build.
        
        then the clock on your build machine is out of sync with the timestamps on the source files. Other errors, apparently unrelated but in fact caused by the clock skew, can occur along with the clock skew warnings. These secondary errors may tend to obscure the fact that the true root cause of the problem is an out-of-sync clock.
        
        If you get an error message like this:
        
        Clock Skew
        
        Specific Build Issues
        
        Make sure your repository is up-to-date
        
        Run hg pull -u to make sure you have the latest changes.
        
        Clean build results
        
        The simplest way to fix incremental rebuild issues is to run make clean. This will remove all build results, but not the configuration or any build system support artifacts. In most cases, this will solve build errors resulting from incremental build mismatches.
        
        Completely clean the build directory.
        
        If this does not work, the next step is to run make dist-clean, or removing the build output directory ($BUILD). This will clean all generated output, including your configuration. You will need to re-run configure after this step. A good idea is to run make print-configuration before running make dist-clean, as this will print your current configure command line. Here's a way to do this:
        
        make print-configuration > current-configuration
        make dist-clean
        bash configure $(cat current-configuration)
        make
        
        Re-clone the Mercurial repository
        
        Sometimes the Mercurial repository gets in a state that causes the product to be un-buildable. In such a case, the simplest solution is often the "sledgehammer approach": delete the entire repository, and re-clone it. If you have local changes, save them first to a different location using hg export.
        
        Here are a suggested list of things to try if you are having unexpected build problems. Each step requires more time than the one before, so try them in order. Most issues will be solved at step 1 or 2.
        
        Incremental rebuilds mean that when you modify part of the product, only the affected parts get rebuilt. While this works great in most cases, and significantly speed up the development process, from time to time complex interdependencies will result in an incorrect build result. This is the most common cause for unexpected build problems.
        
        Problems with Incremental Rebuilds
        
        By default, the JDK has a strict approach where warnings from the compiler is considered errors which fail the build. For very new or very old compiler versions, this can trigger new classes of warnings, which thus fails the build. Run configure with --disable-warnings-as-errors to turn of this behavior. (The warnings will still show, but not make the build fail.)
        
        Verify that the summary at the end looks correct. Are you indeed using the Boot JDK and native toolchain that you expect?
        
        Make sure your configuration is correct. Re-run configure, and look for any warnings. Warnings that appear in the middle of the configure output is also repeated at the end, after the summary. The entire log is stored in $BUILD/configure.log.
        
        Problems with the Build Environment
        
        Sometimes the build can fail with no apparent changes that have caused the failure. If this is the first time you are building the JDK on this particular computer, and the build fails, the problem is likely with your build environment. But even if you have previously built the JDK with success, and it now fails, your build environment might have changed (perhaps due to OS upgrades or similar). But most likely, such failures are due to problems with the incremental rebuild.
        
        Most of the time, the build will fail due to incorrect changes in the source code.
        
        Fixing Unexpected Build Failures
        
        You can increase the verbosity of the log file, by the LOG control variable to make. If you want to see the command lines used in compilations, use LOG=cmdlines. To increase the general verbosity, use LOG=info, LOG=debug or LOG=trace. Both of these can be combined with cmdlines, e.g. LOG=info,cmdlines. The debug log level will show most shell commands executed by make, and trace will show all. Beware that both these log levels will produce a massive build log!
        
        The output (stdout and stderr) from the latest build is always stored in $BUILD/build.log. The previous build log is stored as build.log.old. This means that it is not necessary to redirect the build output yourself if you want to process it.
        
        Checking the Build Log File
        
        Note that the build failure summary will only help you if the issue was a compilation failure or similar. If the problem is more esoteric, or is due to errors in the build machinery, you will likely get empty output logs, and No indication of failed target found instead of the make target chain.
        
        Finally, some hints are given on how to locate the error in the complete log. In this example, we would try searching the log file for "psMemoryPool.o". Another way to quickly locate make errors in the log is to search for "] Error" or "***".
        
        Another way to trace the failure is to follow the chain of make targets, from top-level targets to individual file targets. Between Make failed targets repeated here and End of repeated output the output from make showing this chain is repeated. The first failed recipe will typically contain the full path to the file in question that failed to compile. Following lines will show a trace of make targets why we ended up trying to compile that file.
        
        The path to the failure-logs directory is printed. In this file you will find a <target>.log file that contains the output from this command in its entirety, and also a <target>.cmd, which contain the complete command line used for running this command. You can re-run the failing command by executing . <path to failure-logs>/<target>.cmd in your shell.
        
        Then, between the Output from failing command(s) repeated here and End of repeated output the first lines of output (stdout and stderr) from the actual failing command is repeated. In most cases, this is the error message that caused the build to fail. If multiple commands were failing (this can happen in a parallel build), output from all failed commands will be printed here.
        
        Let's break it down! First, the selected configuration, and the top-level target you entered on the command line that caused the failure is printed.
        
        Building the JDK requires a lot of horsepower. Some of the build tools can be adjusted to utilize more or less of resources such as parallel threads and memory. The configure script analyzes your system and selects reasonable values for such options based on your hardware. If you encounter resource problems, such as out of memory conditions, you can modify the detected values with:
        
        Build Performance
        
        Copy these folders to your target system. Then you can run e.g. images/jdk/bin/java -version.
        
        Inside this build output directory, the images/jdk will contain the newly built JDK, for your target system.
        
        The build will end up in a directory named like build/linux-arm-normal-server-release.
        
        Verifying the Build
        
        A common cross-compilation target is the ARM CPU. When building for ARM, it is useful to set the ABI profile. A number of pre-defined ABI profiles are available using --with-abi-profile: arm-vfp-sflt, arm-vfp-hflt, arm-sflt, armv5-vfp-sflt, armv6-vfp-hflt. Note that soft-float ABIs are no longer properly supported by the JDK.
        
        Building for ARM/aarch64
        
        Additional architectures might be supported by Debian/Ubuntu Ports.
        
        x86 default default i386 i386-linux-gnu armhf gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf armhf arm-linux-gnueabihf aarch64 gcc-aarch64-linux-gnu g++-aarch64-linux-gnu arm64 aarch64-linux-gnu ppc64el gcc-powerpc64le-linux-gnu g++-powerpc64le-linux-gnu ppc64el powerpc64le-linux-gnu s390x gcc-s390x-linux-gnu g++-s390x-linux-gnu s390x s390x-linux-gnu
        
        Target CC CXX --arch=... --openjdk-target=...
        
        Architectures that are known to successfully cross-compile like this are:
        
        The build does not create new files in that chroot, so it can be reused for multiple builds without additional cleanup.
        
        Configure and build with newly created chroot as sysroot/toolchain-path:
        
        Create chroot on the build system, configuring it for target system:
        
        Install cross-compiler on the build system:
        
        For example, cross-compiling to AArch64 from x86_64 could be done like this:
        
        Fortunately, you can create sysroots for foreign architectures with tools provided by your OS. On Debian/Ubuntu systems, one could use qemu-deboostrap to create the target system chroot, which would have the native libraries and headers specific to that target system. After that, we can use the cross-compiler on the build system, pointing into chroot to get the build dependencies right. This allows building for foreign architectures with native compilation speed.
        
        Creating And Using Sysroots With qemu-deboostrap
        
        Go to Debian Package Search, search for the following packages for your target system, and download them to /tmp/target-x11:
        
        libxi
        
        libxi-dev
        
        x11proto-core-dev
        
        x11proto-input-dev
        
        x11proto-kb-dev
        
        x11proto-render-dev
        
        x11proto-xext-dev
        
        libice-dev
        
        libxrender
        
        libxrender-dev
        
        libxrandr-dev
        
        libsm-dev
        
        libxt-dev
        
        libx11
        
        libx11-dev
        
        libxtst
        
        libxtst-dev
        
        libxext
        
        libxext-dev
        
        Install the libraries into the cross-compilation toolchain. For instance:
        
        cd /tools/gcc-linaro-arm-linux-gnueabihf-raspbian-2012.09-20120921_linux/arm-linux-gnueabihf/libc/usr
        mkdir X11R6
        cd X11R6
        for deb in /tmp/target-x11/*.deb ; do dpkg-deb -x $deb . ; done
        mv usr/* .
        cd lib
        cp arm-linux-gnueabihf/* .
        
        cp: cannot stat `arm-linux-gnueabihf/libICE.so': No such file or directory
        cp: cannot stat `arm-linux-gnueabihf/libSM.so': No such file or directory
        cp: cannot stat `arm-linux-gnueabihf/libXt.so': No such file or directory
        
        If the X11 libraries are not properly detected by configure, you can point them out by --with-x.
        
        You can ignore the following messages. These libraries are not needed to successfully complete a full JDK build.
        
        Note that X11 is needed even if you only want to build a headless JDK.
        
        You will need X11 libraries suitable for your target system. For most cases, using Debian's pre-built libraries work fine.
        
        X11
        
        If alsa is not properly detected by configure, you can point it out by --with-alsa.
        
        Go to Debian Package Search and search for the libasound2 and libasound2-dev packages for your target system. Download them to /tmp.
        
        Install the libraries into the cross-compilation toolchain. For instance:
        
        Note that alsa is needed even if you only want to build a headless JDK.
        
        You will need alsa libraries suitable for your target system. For most cases, using Debian's pre-built libraries work fine.
        
        ALSA
        
        Make sure that the libraries you point to (ALSA, X11, etc) are for the target, not the build, platform.
        
        Take care not to replace the build system's version of these libraries by mistake, since that can render the build machine unusable.
        
        You will need copies of external native libraries for the target system, present on the build machine while building.
        
        Native Libraries
        
        It is often helpful to locate the cross-compilation tools, headers and libraries in a separate directory, outside the normal path, and point out that directory to configure. Do this by setting the sysroot (--with-sysroot) and appending the directory when searching for cross-compilations tools (--with-toolchain-path). As a compact form, you can also use --with-devkit to point to a single directory, if it is correctly setup. (See basics.m4 for details.)
        
        The build toolchain will be autodetected just the same way the normal build/target toolchain will be autodetected when not cross-compiling. If this is not what you want, or if the autodetection fails, you can specify a devkit containing the build toolchain using --with-build-devkit to configure, or by giving BUILD_CC and BUILD_CXX arguments.
        
        You will need two copies of your toolchain, one which generates output that can run on the target system (the normal, or target, toolchain), and one that generates output that can run on the build system (the build toolchain). Note that cross-compiling is only supported for gcc at the time being. The gcc standard is to prefix cross-compiling toolchains with the target denominator. If you follow this standard, configure is likely to pick up the toolchain correctly.
        
        Toolchain Considerations
        
        You must specify the target platform when cross-compiling. Doing so will also automatically turn the build into a cross-compiling mode. The simplest way to do this is to use the --openjdk-target argument, e.g. --openjdk-target=arm-linux-gnueabihf. or --openjdk-target=aarch64-oe-linux. This will automatically set the --build, --host and --target options for autoconf, which can otherwise be confusing. (In autoconf terminology, the "target" is known as "host", and "target" is used for building a Canadian cross-compiler.)
        
        Specifying the Target Platform
        
        The build process will create a minimal Build JDK for you, as part of building. To speed up the build, you can use --with-build-jdk to configure to point to a pre-built Build JDK. Please note that the build result is unpredictable, and can possibly break in subtle ways, if the Build JDK does not exactly match the current sources.
        
        To be able to build, we need a "Build JDK", which is a JDK built from the current sources (that is, the same as the end result of the entire build process), but able to run on the build system, and not the target system. (In contrast, the Boot JDK should be from an older release, e.g. JDK 8 when building JDK 9.)
        
        When cross-compiling, make sure you use a boot JDK that runs on the build system, and not on the target system.
        
        Boot JDK and Build JDK
        
        Notice that devkits are not only useful for targeting different build platforms. Because they contain the full build dependencies for a system (i.e. compiler and root file system), they can easily be used to build well-known, reliable and reproducible build environments. You can for example create and use a devkit with GCC 7.3 and a Fedora 12 sysroot environment (with glibc 2.11) on Ubuntu 14.04 (which doesn't have GCC 7.3 by default) to produce OpenJDK binaries which will run on all Linux systems with runtime libraries newer than the ones from Fedora 12 (e.g. Ubuntu 16.04, SLES 11 or RHEL 6).
        
        BASE_OS must be one of "OEL6" for Oracle Enterprise Linux 6 or "Fedora" (if not specified "OEL6" will be the default). If the base OS is "Fedora" the corresponding Fedora release can be specified with the help of the BASE_OS_VERSION option (with "27" as default version). If the build is successful, the new devkits can be found in the build/devkit/result subdirectory:
        
        x86_64-linux-gnu aarch64-linux-gnu arm-linux-gnueabihf ppc64-linux-gnu ppc64le-linux-gnu s390x-linux-gnu
        
        Supported devkit targets
        
        where TARGETS contains one or more TARGET_TRIPLETs of the form described in section 3.4 of the GNU Autobook. If no targets are given, a native toolchain for the current platform will be created. Currently, at least the following targets are known to work:
        
        Devkits can be created from the make/devkit directory by executing:
        
        will configure and build OpenJDK for Linux/ppc64 assuming that <devkit-path> points to a Linux/x86_64 to Linux/ppc64 devkit.
        
        The OpenJDK build system provides out-of-the box support for creating and using so called devkits. A devkit is basically a collection of a cross-compiling toolchain and a sysroot environment which can easily be used together with the --with-devkit configure option to cross compile the OpenJDK. On Linux/x86_64, the following command:
        
        Cross compiling the easy way with OpenJDK devkits
        
        If all you want to do is to compile a 32-bit version, for the same OS, on a 64-bit machine, consider using --with-target-bits=32 instead of doing a full-blown cross-compilation. (While this surely is possible, it's a lot more work and will take much longer to build.)
        
        Cross-compiling the JDK requires you to be able to build both for the build platform and for the target platform. The reason for the former is that we need to build and execute tools during the build process, both native tools and Java tools.
        
        This requires a more complex setup and build procedure. This section assumes you are familiar with cross-compiling in general, and will only deal with the particularities of cross-compiling the JDK. If you are new to cross-compiling, please see the external links at Wikipedia for a good start on reading materials.
        
        The typical reason for cross-compiling is that the build is performed on a more powerful desktop computer, but the resulting binaries will be able to run on a different, typically low-performing system. Most of the complications that arise when building for embedded is due to this separation of build and target systems.
        
        Cross-compiling means using one platform (the build platform) to generate output that can ran on another platform (the target platform).
        
        Cross-compiling
        
        For more details on how to run tests, please see the Testing the JDK document.
    General Make Control Variables
    
    However, there are a few make variables, known as control variables that are supposed to be overriden on the command line. These make up the "make time" configuration, as opposed to the "configure time" configuration.
    
    Normally, this is not recommended. If used improperly, it can lead to a broken build. Unless you're well versed in the build system, this is hard to use properly. Therefore, make will print a warning if this is detected.
    
    It is possible to control make behavior by overriding the value of make variables, either on the command line or in the environment.
    
    Make Control Variables
    - clean-<outputdir> - Remove the subdir in the output dir with the name
    - clean-<phase> - Remove all build results related to a certain build phase
    - clean-<module> - Remove all build results related to a certain module
    - clean-<module>-<phase> - Remove all build results related to a certain module and phase
    Similarly, it is possible to clean just a part of the build by creating make targets according to these patterns:
    - <phase> - Build the specified phase and everything it depends on
    - <module> - Build the specified module and everything it depends on
    - <module>-<phase> - Compile the specified phase for the specified module and everything it depends on
    using-fine-grained-make-targets) for more details about this functionality.
    
    It is possible to build just a single module, a single phase, or a single phase of a single module, by creating make targets according to these followin patterns. A phase can be either of gensrc, gendata, copy, java, launchers, or libs. See [Using Fine-Grained Make Targets](
    
    Run make help to get an up-to-date list of important make targets and make control variables.
    - hotspot - Build all of hotspot (but only hotspot)
    - hotspot-<variant> - Build just the specified jvm variant
    - images or product-images - Build the JDK image
    - docs or docs-image - Build the documentation image
    - test-image - Build the test image
    - all or all-images - Build all images (product, docs and test)
    - bootcycle-images - Build images twice, second time with newly built JDK (good for testing)
    - clean - Remove all files generated by make, but not those generated by configure
    - dist-clean - Remove all files, including configuration
    Apart from the default target, here are some common make targets:
    
    Common Make Targets
    
    The output of the exploded image resides in $BUILD/jdk. You can test the newly built JDK like this: $BUILD/jdk/bin/java -version.
    
    When running make without any arguments, the default target is used, which is the same as running make default or make jdk. This will build a minimal (or roughly minimal) set of compiled output (known as an "exploded image") needed for a developer to actually execute the newly built JDK. The idea is that in an incremental development fashion, when doing a normal make, you should only spend time recompiling what's changed (making it purely incremental) and only do the work that's needed to actually run and test your code.
    
    When you have a proper configuration, all you need to do to build the JDK is to run make. (But see the warning at GNU Make about running the correct version of make.)
    
    Running Make
    
    Also note that, despite what autoconf claims, setting CFLAGS will not accomplish anything. Instead use --with-extra-cflags (and similar for cxxflags and ldflags).
    
    If a configure argument exists, use that instead, e.g. use --with-jtreg instead of setting JTREGEXE.
    
    However, there are a few configure variables, known as control variables that are supposed to be overriden on the command line. These are variables that describe the location of tools needed by the build, like MAKE or GREP. If any such variable is specified, configure will use that value instead of trying to autodetect the tool. For instance, bash configure MAKE=/opt/gnumake4.0/bin/make.
    
    Normally, this is not recommended. If used improperly, it can lead to a broken configuration. Unless you're well versed in the build system, this is hard to use properly. Therefore, configure will print a warning if this is detected.
    
    It is possible to control certain aspects of configure by overriding the value of configure variables, either on the command line or in the environment.
    
    Configure Control Variables
    - --with-stdc++lib=<method> - Use the specified method (static, dynamic or default) for linking the C++ runtime.
    On Linux, it is possible to select either static or dynamic linking of the C++ runtime. The default is static linking, with dynamic linking as fallback if the static library is not found.
    - --with-libjpeg=<source> - Use the specified source for libjpeg
    - --with-giflib=<source> - Use the specified source for giflib
    - --with-libpng=<source> - Use the specified source for libpng
    - --with-lcms=<source> - Use the specified source for lcms
    - --with-zlib=<source> - Use the specified source for zlib
    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 libjpeg, giflib, libpng and lcms. For zlib, the system lib (if present) is used except on Windows and AIX. However the bundled libraries may be replaced by an external version. To do so, specify system as the <source> option in these arguments. (The default is bundled).
    - --with-boot-jdk=<path> - Set the path to the [Boot JDK](
      
      boot-jdk-requirements)
    - --with-freetype=<path> - Set the path to FreeType
    - --with-cups=<path> - Set the path to CUPS
    - --with-x=<path> - Set the path to X11
    - --with-alsa=<path> - Set the path to ALSA
    - --with-libffi=<path> - Set the path to libffi
    - --with-jtreg=<path> - Set the path to JTReg. See [Running Tests](
      
      running-tests)
    Configure Arguments for External Dependencies
    - --with-devkit=<path> - Use this devkit for compilers, tools and resources
    - --with-sysroot=<path> - Use this directory as sysroot
    - --with-extra-path=<path>[;<path>] - Prepend these directories to the default path when searching for all kinds of binaries
    - --with-toolchain-path=<path>[;<path>] - Prepend these directories when searching for toolchain binaries (compilers etc)
    - --with-extra-cflags=<flags> - Append these flags when compiling JDK C files
    - --with-extra-cxxflags=<flags> - Append these flags when compiling JDK C++ files
    - --with-extra-ldflags=<flags> - Append these flags when linking JDK libraries
    Configure Arguments for Native Compilation
    - --with-jni-libpath=<path> - Use the specified path as a default when searching for runtime libraries.
    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 overriden at runtime by setting the java.library.path property.
    - --enable-debug - Set the debug level to fastdebug (this is a shorthand for --with-debug-level=fastdebug)
    - --with-debug-level=<level> - Set the debug level, which can be release, fastdebug, slowdebug or optimized. Default is release. optimized is variant of release with additional Hotspot debug code.
    - --with-native-debug-symbols=<method> - Specify if and how native debug symbols should be built. Available methods are none, internal, external, zipped. Default behavior depends on platform. See Native Debug Symbols for more details.
    - --with-version-string=<string> - Specify the version string this build will be identified with.
    - --with-version-<part>=<value> - A group of options, where <part> can be any of pre, opt, build, major, minor, security or patch. Use these options to modify just the corresponding part of the version string from the default, or the value provided by --with-version-string.
    - --with-jvm-variants=<variant>[,<variant>...] - Build the specified variant (or variants) of Hotspot. Valid variants are: server, client, minimal, core, zero, custom. Note that not all variants are possible to combine in a single build.
    - --enable-jvm-feature-<feature> or --disable-jvm-feature-<feature> - Include (or exclude) <feature> as a JVM feature in Hotspot. You can also specify a list of features to be enabled, separated by space or comma, as --with-jvm-features=<feature>[,<feature>...]. If you prefix <feature> with a -, it will be disabled. These options will modify the default list of features for the JVM variant(s) you are building. For the custom JVM variant, the default list is empty. A complete list of valid JVM features can be found using bash configure --help.
    - --with-target-bits=<bits> - Create a target binary suitable for running on a <bits> 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 reduced build.)
    Configure Arguments for Tailoring the Build
    
    (Note that this help text also include general autoconf options, like --dvidir, that is not relevant to the JDK. To list only JDK-specific features, use bash configure --help=short instead.)
    
    To get up-to-date information on all available configure argument, please run:
    
    Here follows some of the most common and important configure argument.
    
    Common Configure Arguments
  Some command line examples:
  
  configure 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.
  
  This will create an output directory containing the configuration and setup an area for the build result. This directory typically looks like build/linux-x64-server-release, but the actual name depends on your specific configuration. (It can also be set directly, see Using Multiple Configurations). This directory is referred to as $BUILD in this documentation.
  
  The configuration is created by the configure script. The basic invocation of the configure script looks like this:
  
  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.
  
  Running Configure
  
  At least version 3.2 of GNU Bash must be used.
  
  The JDK requires GNU Bash. No other shells are supported.
  
  GNU Bash
  
  If you want to override the default make found by configure, use the MAKE configure variable, e.g. configure MAKE=/opt/gnu/make.
  
  Note that configure locates and verifies a properly functioning version of make and stores the path to this make binary in the configuration. If you start a build using make on the command line, you will be using the version of make found first in your PATH, 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 configure will be called. Normally, this will present no issues, but if you have a very old make, or a non-GNU Make make in your path, this might cause issues.
  
  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 --with-output-sync) and speed and stability improvements.
  
  The JDK requires GNU Make. No other flavors of make are supported.
  
  GNU Make
  
  If configure has problems locating your installation of autoconf, you can specify it using the AUTOCONF environment variable, like this:
  - To install on an apt-based Linux, try running sudo apt-get install autoconf.
  - To install on an rpm-based Linux, try running sudo yum install autoconf.
  - To install on macOS, try running brew install autoconf.
  - To install on Windows, try running <path to Cygwin setup>/setup-x86_64 -q -P autoconf.
  The JDK requires Autoconf on all platforms. At least version 2.69 is required.
  
  Autoconf
  
  Build Tools Requirements
  
  Use --with-libffi=<path> if configure does not properly locate your libffi files.
  - To install on an apt-based Linux, try running sudo apt-get install libffi-dev.
  - To install on an rpm-based Linux, try running sudo yum install libffi-devel.
  libffi, the Portable Foreign Function Interface Library is required when building the Zero version of Hotspot.
  
  libffi
  
  Use --with-alsa=<path> if configure does not properly locate your ALSA files.
  - To install on an apt-based Linux, try running sudo apt-get install libasound2-dev.
  - To install on an rpm-based Linux, try running sudo yum install alsa-lib-devel.
  ALSA, Advanced Linux Sound Architecture is required on Linux. At least version 0.9.1 of ALSA is required.
  
  ALSA
  
  Use --with-x=<path> if configure does not properly locate your X11 files.
  - To install on an apt-based Linux, try running sudo apt-get install libx11-dev libxext-dev libxrender-dev libxrandr-dev libxtst-dev libxt-dev.
  - To install on an rpm-based Linux, try running sudo yum install libXtst-devel libXt-devel libXrender-devel libXrandr-devel libXi-devel.
  Certain X11 libraries and include files are required on Linux.
  
  X11
  
  Use --with-cups=<path> if configure does not properly locate your CUPS files.
  - To install on an apt-based Linux, try running sudo apt-get install libcups2-dev.
  - To install on an rpm-based Linux, try running sudo yum install cups-devel.
  CUPS, Common UNIX Printing System header files are required on all platforms, except Windows. Often these files are provided by your operating system.
  
  CUPS
  
  Use --with-freetype-include=<path> and --with-freetype-lib=<path> if configure does not automatically locate the platform FreeType files.
  - To install on an apt-based Linux, try running sudo apt-get install libfreetype6-dev.
  - To install on an rpm-based Linux, try running sudo yum install freetype-devel.
  FreeType2 from The FreeType Project 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.
  
  FreeType
  
  As a fallback, the second version allows you to point to the include directory and the lib directory separately.
  
  If a required library is not detected by configure, you need to provide the path to it. There are two forms of the configure arguments to point to an external library: --with-<LIB>=<path> or --with-<LIB>-include=<path to include> --with-<LIB>-lib=<path to lib>. 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.
  
  Different platforms require different external libraries. In general, libraries are not optional - that is, they are either required or not used.
  
  External Library Requirements
  
  On Linux you can also get a JDK from the Linux distribution. On apt-based distros (like Debian and Ubuntu), sudo apt-get install openjdk-<VERSION>-jdk is typically enough to install a JDK <VERSION>. On rpm-based distros (like Fedora and Red Hat), try sudo yum install java-<VERSION>-openjdk-devel.
  
  JDK binaries for Linux, Windows and macOS can be downloaded from jdk.java.net. An alternative is to download the Oracle JDK. Another is the Adopt OpenJDK Project, which publishes experimental prebuilt binaries for various platforms.
  
  Getting JDK binaries
  
  If the boot JDK is not automatically detected, or the wrong JDK is picked, use --with-boot-jdk to point to the JDK to use.
  
  Early in the release cycle, version N-1 may not yet have been released. In that case, the preferred boot JDK will be version N-2 until version N-1 is available.
  
  The rule of thumb is that the boot JDK for building JDK major version N should be a JDK of major version N-1, so for building JDK 9 a JDK 8 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 N-1 rule, make sure you've got the latest update version, since JDK 8 GA might not be able to build JDK 9 on all platforms.
  
  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.
  
  Boot JDK Requirements
  
  Please consult the AIX section of the Supported Build Platforms OpenJDK Build Wiki page for details about which versions of XLC are supported.
  
  IBM XL C/C++
  
  If you get LINK: fatal error LNK1123: failure during conversion to COFF: file invalid when building using Visual Studio 2010, you have encountered KB2757355, a bug triggered by a specific installation order. However, the solution suggested by the KB article does not always resolve the problem. See this stackoverflow discussion for other suggestions.
  
  If you have multiple versions of Visual Studio installed, configure will by default pick the latest. You can request a specific version to be used by setting --with-toolchain-version, e.g. --with-toolchain-version=2015.
  1. Versions older than 2017 are unlikely to continue working for long.
  The minimum accepted version of Visual Studio is 2010. Older versions will not be accepted by configure. The maximum accepted version of Visual Studio is
  
  Microsoft Visual Studio
  
  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 Problems with the Build Environment, and Getting Help to find out if there are any recent, non-merged patches available for this update.
  
  It is advisable to keep an older version of Xcode for building the JDK when updating Xcode. This blog page has good suggestions on managing multiple Xcode versions. To use a specific version of Xcode, use xcode-select -s before running configure, or use --with-toolchain-path to point to the version of Xcode to use, e.g. configure --with-toolchain-path=/Applications/Xcode8.app/Contents/Developer/usr/bin
  
  You will need the Xcode command lines developers tools to be able to build the JDK. (Actually, only the command lines tools are needed, not the IDE.) The simplest way to install these is to run:
  
  The oldest supported version of Xcode is 8.
  
  Apple Xcode
  
  To use clang instead of gcc on Linux, use --with-toolchain-type=clang.
  
  The minimum accepted version of clang is 3.2. Older versions will not be accepted by configure.
  
  clang
  
  In general, any version between these two should be usable.
  
  The JDK is currently known to be able to compile with at least version 9.2 of gcc.
  
  The minimum accepted version of gcc is 5.0. Older versions will generate a warning by configure and are unlikely to work.
  
  gcc
  
  All compilers are expected to be able to compile to the C99 language standard, as some C99 features are used in the source code. Microsoft Visual Studio doesn't fully support C99 so in practice shared code is limited to using C99 features that it does support.
  
  Linux gcc 9.2.0 macOS Apple Xcode 10.1 (using clang 10.0.0) Windows Microsoft Visual Studio 2019 update 16.5.3
  
  Operating system Toolchain version
  
  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.
  
  Linux gcc, clang macOS Apple Xcode (using clang) AIX IBM XL C/C++ Windows Microsoft Visual Studio
  
  Operating system Supported toolchain
  
  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.
  
  Native Compiler (Toolchain) Requirements
  
  Please consult the AIX section of the Supported Build Platforms OpenJDK Build Wiki page for details about which versions of AIX are supported.
  
  AIX
  
  For rpm-based distributions (Fedora, Red Hat, etc), try this:
  
  For apt-based distributions (Debian, Ubuntu, etc), try this:
  
  The basic tooling is provided as part of the core operating system, but you will most likely need to install developer packages.
  
  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.
  
  Linux
  
  The standard macOS environment contains the basic tooling needed to build, but for external libraries a package manager is recommended. The JDK uses homebrew in the examples, but feel free to use whatever manager you want (or none).
  
  It is recommended that you use at least Mac OS X 10.13 (High Sierra). At the time of writing, the JDK has been successfully compiled on macOS 10.12 (Sierra).
  
  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 Apple Xcode on some strategies to deal with this.
  
  macOS
  
  Note that while it's possible to build on WSL, testing is still not fully supported.
  
  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.
  
  It's 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 --build=x86_64-unknown-linux-gnu --host=x86_64-unknown-linux-gnu to configure.
  
  Windows 10 1809 or newer is supported due to a dependency on the wslpath utility and support for environment variable sharing through WSLENV. Version 1803 can work but intermittent build failures have been observed.
  
  Windows Subsystem for Linux (WSL)
  
  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 "BLODA" list and the section on fork() failures.

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Mac 编译jdk源码小记

build-tools-requirements), [external libraries](

external-library-requirements) or the boot JDK),

Introduction

Getting the Source Code

Special Considerations

Build Hardware Requirements

Building on x86

Building on aarch64

Building on 32-bit arm

cross-compiling).

Operating System Requirements

Windows

Cygwin

Test Make Control Variables

Advanced Make Control Variables

Running Tests

Disk Speed

Virus Checking

Ccache

Precompiled Headers

Icecc / icecream

Using sjavac

Building the Right Target

Troubleshooting

Locating the Source of the Error

Build Failure Summary

Rebuilding Part of java.base (JDK_FILTER)

Learn About Mercurial

Understanding the Build System

Configurations

Build Output Structure

Override styles from the base CSS file that are not ideal for this document.

Contributing to the JDK

Developing the Build System Itself

Autoconf Details

Native Debug Symbols

Fixpath

Skipping the Dependency Check

Building Individual Module Phases

Building Individual Modules

Using Fine-Grained Make Targets

Handling Reconfigurations

Using Multiple Configurations

Bash Completion

Setting Up a Repository for Pushing Changes (defpath)

Hints and Suggestions for Advanced Users

contributing-to-openjdk) for more information.

Getting Help

Out of Memory Errors

Clock Skew

Specific Build Issues

Problems with Incremental Rebuilds

Problems with the Build Environment

Fixing Unexpected Build Failures

Checking the Build Log File

Build Performance

Verifying the Build

Building for ARM/aarch64

Creating And Using Sysroots With qemu-deboostrap

X11

ALSA

Native Libraries

Toolchain Considerations

Specifying the Target Platform

Boot JDK and Build JDK

Supported devkit targets

Cross compiling the easy way with OpenJDK devkits

Cross-compiling

General Make Control Variables

Make Control Variables

using-fine-grained-make-targets) for more details about this functionality.

Common Make Targets

Running Make

Configure Control Variables

boot-jdk-requirements)

running-tests)

Configure Arguments for External Dependencies

Configure Arguments for Native Compilation