8205956: Fix usage of "OpenJDK" in build and test instructions
Reviewed-by: erikj, tbell
% Building the JDK## TL;DR (Instructions for the Impatient)If you are eager to try out building the JDK, these simple steps works most ofthe time. They assume that you have installed Mercurial (and Cygwin if runningon Windows) and cloned the top-level JDK repository that you want to build. 1. [Get the complete source code](#getting-the-source-code): \ `hg clone http://hg.openjdk.java.net/jdk/jdk` 2. [Run configure](#running-configure): \ `bash configure` If `configure` fails due to missing dependencies (to either the [toolchain](#native-compiler-toolchain-requirements), [build tools]( #build-tools-requirements), [external libraries]( #external-library-requirements) or the [boot JDK](#boot-jdk-requirements)), 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. 3. [Run make](#running-make): \ `make images` 4. Verify your newly built JDK: \ `./build/*/images/jdk/bin/java -version` 5. [Run basic tests](##running-tests): \ `make run-test-tier1`If any of these steps failed, or if you want to know more about buildrequirements or build functionality, please continue reading this document.## IntroductionThe JDK is a complex software project. Building it requires a certain amount oftechnical expertise, a fair number of dependencies on external software, andreasonably powerful hardware.If you just want to use the JDK and not build it yourself, this document is notfor you. See for instance [OpenJDK installation](http://openjdk.java.net/install) for some methods of installing a prebuiltJDK.## Getting the Source CodeMake sure you are getting the correct version. As of JDK 10, the source is nolonger split into separate repositories so you only need to clone one singlerepository. At the [OpenJDK Mercurial server](http://hg.openjdk.java.net/) youcan see a list of all available forests. If you want to build an older version,e.g. JDK 8, it is recommended that you get the `jdk8u` forest, which containsincremental 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'sGuide](http://www.mercurial-scm.org/guide). The rest of this document assumes aworking knowledge of Mercurial.### Special ConsiderationsFor a smooth building experience, it is recommended that you follow these ruleson 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, extra care must be taken to make sure the [Cygwin](#cygwin) 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 RequirementsThe JDK is a massive project, and require machines ranging from decent topowerful to be able to build in a reasonable amount of time, or to be able tocomplete a build at all.We *strongly* recommend usage of an SSD disk for the build, since disk speed isone of the limiting factors for build performance.### Building on x86At 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 diskspace is required (8 GB minimum for building on Solaris).Even for 32-bit builds, it is recommended to use a 64-bit build machine, andinstead create a 32-bit target using `--with-target-bits=32`.### Building on sparcAt a minimum, a machine with 4 cores is advisable, as well as 4 GB of RAM. (Themore cores to use, the more memory you need.) At least 8 GB of free disk spaceis required.### Building on arm/aarch64This is not recommended. Instead, see the section on [Cross-compiling](#cross-compiling).## Operating System RequirementsThe mainline JDK project supports Linux, Solaris, 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 operatingsystems, but the further you deviate from what is tested on a daily basis, themore likely you are to run into problems.This table lists the OS versions used by Oracle when building the JDK. Suchinformation is always subject to change, but this table is up to date at thetime of writing. Operating system Vendor/version used ----------------- ------------------------------------------------------- Linux Oracle Enterprise Linux 6.4 / 7.1 (using kernel 3.8.13) Solaris Solaris 11.1 SRU 21.4.1 / 11.2 SRU 5.5 macOS Mac OS X 10.9 (Mavericks) / 10.10 (Yosemite) Windows Windows Server 2012 R2The double version numbers for Linux, Solaris and macOS is due to the hybridmodel used at Oracle, where header files and external libraries from an olderversion are used when building on a more modern version of the OS.The Build Group has a wiki page with [Supported Build Platforms](https://wiki.openjdk.java.net/display/Build/Supported+Build+Platforms). Fromtime to time, this is updated by contributors to list successes or failures ofbuilding on different platforms.### WindowsWindows XP is not a supported platform, but all newer Windows should be able tobuild the JDK.On Windows, it is important that you pay attention to the instructions in the[Special Considerations](#special-considerations).Windows is the only non-POSIX OS supported by the JDK, and as such, requiressome extra care. A POSIX support layer is required to build on Windows.Currently, the only supported such layer is Cygwin. (Msys is no longersupported due to a too old bash; msys2 and the new Windows Subsystem for Linux(WSL) would likely be possible to support in a future version but that wouldrequire 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`. Thisrule 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 sectionon [Fixpath](#fixpath).#### CygwinA functioning [Cygwin](http://www.cygwin.com/) environment is thus required forbuilding the JDK on Windows. If you have a 64-bit OS, we strongly recommendusing the 64-bit version of Cygwin.**Note:** Cygwin has a model of continuously updating all packages without anyeasy way to install or revert to a specific version of a package. This meansthat 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 causeunexpected build problems.The JDK requires GNU Make 4.0 or greater on Windows. This is usually not aproblem, since Cygwin currently only distributes GNU Make at a version above4.0.Apart from the basic Cygwin installation, the following packages must also beinstalled: * `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```Unfortunately, Cygwin can be unreliable in certain circumstances. If youexperience build tool crashes or strange issues when building on Windows,please check the Cygwin FAQ on the ["BLODA" list](https://cygwin.com/faq/faq.html#faq.using.bloda) and the section on [fork()failures](https://cygwin.com/faq/faq.html#faq.using.fixing-fork-failures).### SolarisSee `make/devkit/solaris11.1-package-list.txt` for a list of recommendedpackages to install when building on Solaris. The versions specified in thislist is the versions used by the daily builds at Oracle, and is likely to workproperly.Older versions of Solaris shipped a broken version of `objcopy`. At leastversion 2.21.1 is needed, which is provided by Solaris 11 Update 1. Objcopy isneeded if you want to have external debug symbols. Please make sure you areusing at least version 2.21.1 of objcopy, or that you disable external debugsymbols.### macOSApple is using a quite aggressive scheme of pushing OS updates, and couplingthese updates with required updates of Xcode. Unfortunately, this makes itdifficult for a project such as the JDK to keep pace with a continuously updatedmachine running macOS. See the section on [Apple Xcode](#apple-xcode) on somestrategies to deal with this.It is recommended that you use at least Mac OS X 10.9 (Mavericks). At the timeof writing, the JDK has been successfully compiled on macOS versions up to10.12.5 (Sierra), using XCode 8.3.2 and `--disable-warnings-as-errors`.The standard macOS environment contains the basic tooling needed to build, butfor external libraries a package manager is recommended. The JDK uses[homebrew](https://brew.sh/) in the examples, but feel free to use whatevermanager you want (or none).### LinuxIt is often not much problem to build the JDK on Linux. The only general adviceis to try to use the compilers, external libraries and header files as providedby your distribution.The basic tooling is provided as part of the core operating system, but youwill most likely need to install developer packages.For apt-based distributions (Debian, Ubuntu, etc), try this:```sudo apt-get install build-essential```For rpm-based distributions (Fedora, Red Hat, etc), try this:```sudo yum groupinstall "Development Tools"```### AIXThe regular builds by SAP is using AIX version 7.1, but AIX 5.3 is alsosupported. See the [OpenJDK PowerPC Port Status Page](http://cr.openjdk.java.net/~simonis/ppc-aix-port) for details.## Native Compiler (Toolchain) RequirementsLarge portions of the JDK consists of native code, that needs to be compiled tobe able to run on the target platform. In theory, toolchain and operatingsystem should be independent factors, but in practice there's more or less aone-to-one correlation between target operating system and toolchain. Operating system Supported toolchain ------------------ ------------------------- Linux gcc, clang macOS Apple Xcode (using clang) Solaris Oracle Solaris Studio AIX IBM XL C/C++ Windows Microsoft Visual StudioPlease see the individual sections on the toolchains for versionrecommendations. As a reference, these versions of the toolchains are used, atthe time of writing, by Oracle for the daily builds of the JDK. It should bepossible to compile the JDK with both older and newer versions, but the closeryou stay to this list, the more likely you are to compile successfully withoutissues. Operating system Toolchain version ------------------ ------------------------------------------------------- Linux gcc 7.3.0 macOS Apple Xcode 6.3 (using clang 6.1.0) Solaris Oracle Solaris Studio 12.4 (with compiler version 5.13) Windows Microsoft Visual Studio 2013 update 4### gccThe minimum accepted version of gcc is 4.8. Older versions will generate a warningby `configure` and are unlikely to work.The JDK is currently known to be able to compile with at least version 7.4 ofgcc.In general, any version between these two should be usable.### clangThe minimum accepted version of clang is 3.2. Older versions will not beaccepted by `configure`.To use clang instead of gcc on Linux, use `--with-toolchain-type=clang`.### Apple XcodeThe oldest supported version of Xcode is 5.You will need the Xcode command lines developers tools to be able to buildthe JDK. (Actually, *only* the command lines tools are needed, not the IDE.)The simplest way to install these is to run:```xcode-select --install```It is advisable to keep an older version of Xcode for building the JDK whenupdating Xcode. This [blog page](http://iosdevelopertips.com/xcode/install-multiple-versions-of-xcode.html) hasgood suggestions on managing multiple Xcode versions. To use a specific versionof 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/Xcode5.app/Contents/Developer/usr/bin`If you have recently (inadvertently) updated your OS and/or Xcode version, andthe JDK can no longer be built, please see the section on [Problems with theBuild Environment](#problems-with-the-build-environment), and [GettingHelp](#getting-help) to find out if there are any recent, non-merged patchesavailable for this update.### Oracle Solaris StudioThe minimum accepted version of the Solaris Studio compilers is 5.13(corresponding to Solaris Studio 12.4). Older versions will not be accepted byconfigure.The Solaris Studio installation should contain at least these packages: Package Version -------------------------------------------------- ------------- developer/solarisstudio-124/backend 12.4-1.0.6.0 developer/solarisstudio-124/c++ 12.4-1.0.10.0 developer/solarisstudio-124/cc 12.4-1.0.4.0 developer/solarisstudio-124/library/c++-libs 12.4-1.0.10.0 developer/solarisstudio-124/library/math-libs 12.4-1.0.0.1 developer/solarisstudio-124/library/studio-gccrt 12.4-1.0.0.1 developer/solarisstudio-124/studio-common 12.4-1.0.0.1 developer/solarisstudio-124/studio-ja 12.4-1.0.0.1 developer/solarisstudio-124/studio-legal 12.4-1.0.0.1 developer/solarisstudio-124/studio-zhCN 12.4-1.0.0.1Compiling with Solaris Studio can sometimes be finicky. This is the exactversion used by Oracle, which worked correctly at the time of writing:```$ cc -Vcc: Sun C 5.13 SunOS_i386 2014/10/20$ CC -VCC: Sun C++ 5.13 SunOS_i386 151846-10 2015/10/30```### Microsoft Visual StudioThe minimum accepted version of Visual Studio is 2010. Older versions will notbe accepted by `configure`. The maximum accepted version of Visual Studio is2013.If you have multiple versions of Visual Studio installed, `configure` will bydefault pick the latest. You can request a specific version to be used bysetting `--with-toolchain-version`, e.g. `--with-toolchain-version=2010`.If you get `LINK: fatal error LNK1123: failure during conversion to COFF: fileinvalid` when building using Visual Studio 2010, you have encountered[KB2757355](http://support.microsoft.com/kb/2757355), a bug triggered by aspecific installation order. However, the solution suggested by the KB articledoes not always resolve the problem. See [this stackoverflow discussion](https://stackoverflow.com/questions/10888391) for other suggestions.### IBM XL C/C++The regular builds by SAP is using version 12.1, described as `IBM XL C/C++ forAIX, V12.1 (5765-J02, 5725-C72) Version: 12.01.0000.0017`.See the [OpenJDK PowerPC Port Status Page](http://cr.openjdk.java.net/~simonis/ppc-aix-port) for details.## Boot JDK RequirementsParadoxically, 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 fromthe source code available in the OpenJDK Community. If you are porting the JDKto a new platform, chances are that there already exists another JDK for thatplatform that is usable as boot JDK.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 besuitable as boot JDK. However, the JDK should be able to "build itself", so anup-to-date build of the current JDK source is an acceptable alternative. Ifyou are following the *N-1* rule, make sure you've got the latest updateversion, since JDK 8 GA might not be able to build JDK 9 on all platforms.Early in the release cycle, version *N-1* may not yet have been released. Inthat case, the preferred boot JDK will be version *N-2* until version *N-1*is available.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.### Getting JDK binariesJDK binaries for Linux, Windows and macOS can be downloaded from[jdk.java.net](http://jdk.java.net). An alternative is to download the[Oracle JDK](http://www.oracle.com/technetwork/java/javase/downloads). Anotheris the [Adopt OpenJDK Project](https://adoptopenjdk.net/), which publishesexperimental prebuilt binaries for various platforms.On Linux you can also get a JDK from the Linux distribution. On apt-baseddistros (like Debian and Ubuntu), `sudo apt-get install openjdk-<VERSION>-jdk`is typically enough to install a JDK \<VERSION\>. On rpm-based distros (likeFedora and Red Hat), try `sudo yum install java-<VERSION>-openjdk-devel`.## External Library RequirementsDifferent platforms require different external libraries. In general, librariesare not optional - that is, they are either required or not used.If a required library is not detected by `configure`, you need to provide thepath to it. There are two forms of the `configure` arguments to point to anexternal library: `--with-<LIB>=<path>` or `--with-<LIB>-include=<path toinclude> --with-<LIB>-lib=<path to lib>`. The first variant is more concise,but require the include files an library files to reside in a default hierarchyunder this directory. In most cases, it works fine.As a fallback, the second version allows you to point to the include directoryand the lib directory separately.### FreeTypeFreeType2 from [The FreeType Project](http://www.freetype.org/) is not requiredon any platform. The exception is on Unix-based platforms when configuring suchthat the build artifacts will reference a system installed library,rather than bundling the JDK’s own copy. * 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`. * To install on Solaris, try running `pkg install system/library/freetype-2`.Use `--with-freetype-include=<path>` and `--with-freetype-lib=<path>`if `configure` does not automatically locate the platform FreeType files.### CUPSCUPS, [Common UNIX Printing System](http://www.cups.org) header files arerequired on all platforms, except Windows. Often these files are provided byyour operating system. * 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`. * To install on Solaris, try running `pkg install print/cups`.Use `--with-cups=<path>` if `configure` does not properly locate your CUPSfiles.### X11Certain [X11](http://www.x.org/) libraries and include files are required onLinux and Solaris. * To install on an apt-based Linux, try running `sudo apt-get install libx11-dev libxext-dev libxrender-dev libxtst-dev libxt-dev`. * To install on an rpm-based Linux, try running `sudo yum install libXtst-devel libXt-devel libXrender-devel libXi-devel`. * To install on Solaris, try running `pkg install x11/header/x11-protocols x11/library/libice x11/library/libpthread-stubs x11/library/libsm x11/library/libx11 x11/library/libxau x11/library/libxcb x11/library/libxdmcp x11/library/libxevie x11/library/libxext x11/library/libxrender x11/library/libxscrnsaver x11/library/libxtst x11/library/toolkit/libxt`.Use `--with-x=<path>` if `configure` does not properly locate your X11 files.### ALSAALSA, [Advanced Linux Sound Architecture](https://www.alsa-project.org/) isrequired on Linux. At least version 0.9.1 of ALSA is required. * 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`.Use `--with-alsa=<path>` if `configure` does not properly locate your ALSAfiles.### libffilibffi, the [Portable Foreign Function Interface Library](http://sourceware.org/libffi) is required when building the Zero version ofHotspot. * 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`.Use `--with-libffi=<path>` if `configure` does not properly locate your libffifiles.## Build Tools Requirements### AutoconfThe JDK requires [Autoconf](http://www.gnu.org/software/autoconf) on allplatforms. At least version 2.69 is required. * 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`.If `configure` has problems locating your installation of autoconf, you canspecify it using the `AUTOCONF` environment variable, like this:```AUTOCONF=<path to autoconf> configure ...```### GNU MakeThe JDK requires [GNU Make](http://www.gnu.org/software/make). No other flavorsof make are supported.At least version 3.81 of GNU Make must be used. For distributions supportingGNU Make 4.0 or above, we strongly recommend it. GNU Make 4.0 contains usefulfunctionality to handle parallel building (supported by `--with-output-sync`)and speed and stability improvements.Note that `configure` locates and verifies a properly functioning version of`make` and stores the path to this `make` binary in the configuration. If youstart a build using `make` on the command line, you will be using the versionof make found first in your `PATH`, and not necessarily the one stored in theconfiguration. This initial make will be used as "bootstrap make", and in asecond stage, the make located by `configure` will be called. Normally, thiswill present no issues, but if you have a very old `make`, or a non-GNU Make`make` in your path, this might cause issues.If you want to override the default make found by `configure`, use the `MAKE`configure variable, e.g. `configure MAKE=/opt/gnu/make`.On Solaris, it is common to call the GNU version of make by using `gmake`.### GNU BashThe JDK requires [GNU Bash](http://www.gnu.org/software/bash). No other shellsare supported.At least version 3.2 of GNU Bash must be used.## Running ConfigureTo build the JDK, you need a "configuration", which consists of a directorywhere to store the build output, coupled with information about the platform,the specific build machine, and choices that affect how the JDK is built.The configuration is created by the `configure` script. The basic invocation ofthe `configure` script looks like this:```bash configure [options]```This will create an output directory containing the configuration and setup anarea for the build result. This directory typically looks like`build/linux-x64-normal-server-release`, but the actual name depends on yourspecific configuration. (It can also be set directly, see [Using MultipleConfigurations](#using-multiple-configurations)). This directory is referred toas `$BUILD` in this documentation.`configure` will try to figure out what system you are running on and where allnecessary build components are. If you have all prerequisites for buildinginstalled, it should find everything. If it fails to detect any componentautomatically, it will exit and inform you about the problem.Some command line examples: * 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 ```### Common Configure ArgumentsHere follows some of the most common and important `configure` argument.To get up-to-date information on *all* available `configure` argument, pleaserun:```bash configure --help```(Note that this help text also include general autoconf options, like`--dvidir`, that is not relevant to the JDK. To list only JDK-specificfeatures, use `bash configure --help=short` instead.)#### Configure Arguments for Tailoring the Build * `--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](#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. * `--with-jvm-features=<feature>[,<feature>...]` - Use the specified JVM features when building Hotspot. The list of features will be enabled on top of the default list. For the `custom` JVM variant, this default list is empty. A complete list of available 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 Native Compilation * `--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 External Dependencies * `--with-boot-jdk=<path>` - Set the path to the [Boot JDK]( #boot-jdk-requirements) * `--with-freetype=<path>` - Set the path to [FreeType](#freetype) * `--with-cups=<path>` - Set the path to [CUPS](#cups) * `--with-x=<path>` - Set the path to [X11](#x11) * `--with-alsa=<path>` - Set the path to [ALSA](#alsa) * `--with-libffi=<path>` - Set the path to [libffi](#libffi) * `--with-jtreg=<path>` - Set the path to JTReg. See [Running Tests]( #running-tests)Certain third-party libraries used by the JDK (libjpeg, giflib, libpng, lcmsand zlib) are included in the JDK repository. The default behavior of theJDK build is to use this version of these libraries, but they might bereplaced by an external version. To do so, specify `system` as the `<source>`option in these arguments. (The default is `bundled`). * `--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 zlibOn 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 thestatic library is not found. * `--with-stdc++lib=<method>` - Use the specified method (`static`, `dynamic` or `default`) for linking the C++ runtime.### Configure Control VariablesIt is possible to control certain aspects of `configure` by overriding thevalue of `configure` variables, either on the command line or in theenvironment.Normally, this is **not recommended**. If used improperly, it can lead to abroken configuration. Unless you're well versed in the build system, this ishard to use properly. Therefore, `configure` will print a warning if this isdetected.However, there are a few `configure` variables, known as *control variables*that are supposed to be overriden on the command line. These are variables thatdescribe the location of tools needed by the build, like `MAKE` or `GREP`. Ifany such variable is specified, `configure` will use that value instead oftrying to autodetect the tool. For instance, `bash configureMAKE=/opt/gnumake4.0/bin/make`.If a configure argument exists, use that instead, e.g. use `--with-jtreg`instead of setting `JTREGEXE`.Also note that, despite what autoconf claims, setting `CFLAGS` will notaccomplish anything. Instead use `--with-extra-cflags` (and similar for`cxxflags` and `ldflags`).## Running MakeWhen you have a proper configuration, all you need to do to build the JDK is torun `make`. (But see the warning at [GNU Make](#gnu-make) about running thecorrect version of make.)When running `make` without any arguments, the default target is used, which isthe same as running `make default` or `make jdk`. This will build a minimal (orroughly minimal) set of compiled output (known as an "exploded image") neededfor a developer to actually execute the newly built JDK. The idea is that in anincremental development fashion, when doing a normal make, you should onlyspend time recompiling what's changed (making it purely incremental) and onlydo the work that's needed to actually run and test your code.The output of the exploded image resides in `$BUILD/jdk`. You can test thenewly built JDK like this: `$BUILD/jdk/bin/java -version`.### Common Make TargetsApart from the default target, here are some common make targets: * `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 configurationRun `make help` to get an up-to-date list of important make targets and makecontrol variables.It is possible to build just a single module, a single phase, or a single phaseof a single module, by creating make targets according to these followinpatterns. A phase can be either of `gensrc`, `gendata`, `copy`, `java`,`launchers`, `libs` or `rmic`. See [Using Fine-Grained Make Targets](#using-fine-grained-make-targets) for more details about this functionality. * `<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 onSimilarly, it is possible to clean just a part of the build by creating maketargets according to these patterns: * `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### Make Control VariablesIt is possible to control `make` behavior by overriding the value of `make`variables, either on the command line or in the environment.Normally, this is **not recommended**. If used improperly, it can lead to abroken build. Unless you're well versed in the build system, this is hard touse properly. Therefore, `make` will print a warning if this is detected.However, there are a few `make` variables, known as *control variables* thatare supposed to be overriden on the command line. These make up the "make time"configuration, as opposed to the "configure time" configuration.#### General Make Control Variables * `JOBS` - Specify the number of jobs to build with. See [Build Performance](#build-performance). * `LOG` - Specify the logging level and functionality. See [Checking the Build Log File](#checking-the-build-log-file) * `CONF` and `CONF_NAME` - Selecting the configuration(s) to use. See [Using Multiple Configurations](#using-multiple-configurations)#### Test Make Control VariablesThese make control variables only make sense when running tests. Please see[Testing the JDK](testing.html) for details. * `TEST` * `TEST_JOBS` * `JTREG` * `GTEST`#### Advanced Make Control VariablesThese advanced make control variables can be potentially unsafe. See [Hints andSuggestions for Advanced Users](#hints-and-suggestions-for-advanced-users) and[Understanding the Build System](#understanding-the-build-system) for details. * `SPEC` * `CONF_CHECK` * `COMPARE_BUILD` * `JDK_FILTER`## Running TestsMost of the JDK tests are using the [JTReg](http://openjdk.java.net/jtreg)test framework. Make sure that your configuration knows where to find yourinstallation 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](https://wiki.openjdk.java.net/display/Adoption) providesrecent builds of jtreg [here](https://adopt-openjdk.ci.cloudbees.com/job/jtreg/lastSuccessfulBuild/artifact).Download the latest `.tar.gz` file, unpack it, and point `--with-jtreg` to the`jtreg` directory that you just unpacked.To execute the most basic tests (tier 1), use:```make run-test-tier1```For more details on how to run tests, please see the [Testingthe JDK](testing.html) document.## Cross-compilingCross-compiling means using one platform (the *build* platform) to generateoutput that can ran on another platform (the *target* platform).The typical reason for cross-compiling is that the build is performed on a morepowerful desktop computer, but the resulting binaries will be able to run on adifferent, typically low-performing system. Most of the complications thatarise when building for embedded is due to this separation of *build* and*target* systems.This requires a more complex setup and build procedure. This section assumesyou are familiar with cross-compiling in general, and will only deal with theparticularities of cross-compiling the JDK. If you are new to cross-compiling,please see the [external links at Wikipedia](https://en.wikipedia.org/wiki/Cross_compiler#External_links) for a good starton reading materials.Cross-compiling the JDK requires you to be able to build both for the buildplatform and for the target platform. The reason for the former is that we needto build and execute tools during the build process, both native tools and Javatools.If all you want to do is to compile a 32-bit version, for the same OS, on a64-bit machine, consider using `--with-target-bits=32` instead of doing afull-blown cross-compilation. (While this surely is possible, it's a lot morework and will take much longer to build.)### Boot JDK and Build JDKWhen cross-compiling, make sure you use a boot JDK that runs on the *build*system, and not on the *target* system.To be able to build, we need a "Build JDK", which is a JDK built from thecurrent sources (that is, the same as the end result of the entire buildprocess), 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 whenbuilding JDK 9.)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 pointto 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.### Specifying the Target PlatformYou *must* specify the target platform when cross-compiling. Doing so will alsoautomatically turn the build into a cross-compiling mode. The simplest way todo 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 forautoconf, which can otherwise be confusing. (In autoconf terminology, the"target" is known as "host", and "target" is used for building a Canadiancross-compiler.)### Toolchain ConsiderationsYou will need two copies of your toolchain, one which generates output that canrun on the target system (the normal, or *target*, toolchain), and one thatgenerates output that can run on the build system (the *build* toolchain). Notethat cross-compiling is only supported for gcc at the time being. The gccstandard is to prefix cross-compiling toolchains with the target denominator.If you follow this standard, `configure` is likely to pick up the toolchaincorrectly.The *build* toolchain will be autodetected just the same way the normal*build*/*target* toolchain will be autodetected when not cross-compiling. Ifthis is not what you want, or if the autodetection fails, you can specify adevkit containing the *build* toolchain using `--with-build-devkit` to`configure`, or by giving `BUILD_CC` and `BUILD_CXX` arguments.It is often helpful to locate the cross-compilation tools, headers andlibraries in a separate directory, outside the normal path, and point out thatdirectory to `configure`. Do this by setting the sysroot (`--with-sysroot`) andappending 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` fordetails.)If you are unsure what toolchain and versions to use, these have been provedworking at the time of writing: * [aarch64](https://releases.linaro.org/archive/13.11/components/toolchain/binaries/gcc-linaro-aarch64-linux-gnu-4.8-2013.11_linux.tar.xz) * [arm 32-bit hardware floating point](https://launchpad.net/linaro-toolchain-unsupported/trunk/2012.09/+download/gcc-linaro-arm-linux-gnueabihf-raspbian-2012.09-20120921_linux.tar.bz2)### Native LibrariesYou will need copies of external native libraries for the *target* system,present on the *build* machine while building.Take care not to replace the *build* system's version of these libraries bymistake, since that can render the *build* machine unusable.Make sure that the libraries you point to (ALSA, X11, etc) are for the*target*, not the *build*, platform.#### ALSAYou will need alsa libraries suitable for your *target* system. For most cases,using Debian's pre-built libraries work fine.Note that alsa is needed even if you only want to build a headless JDK. * Go to [Debian Package Search](https://www.debian.org/distrib/packages) 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:```cd /tools/gcc-linaro-arm-linux-gnueabihf-raspbian-2012.09-20120921_linux/arm-linux-gnueabihf/libcdpkg-deb -x /tmp/libasound2_1.0.25-4_armhf.deb .dpkg-deb -x /tmp/libasound2-dev_1.0.25-4_armhf.deb .``` * If alsa is not properly detected by `configure`, you can point it out by `--with-alsa`.#### X11You will need X11 libraries suitable for your *target* system. For most cases,using Debian's pre-built libraries work fine.Note that X11 is needed even if you only want to build a headless JDK. * Go to [Debian Package Search](https://www.debian.org/distrib/packages), 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 * 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/* . ``` You can ignore the following messages. These libraries are not needed to successfully complete a full JDK build. ``` 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`.### Building for ARM/aarch64A common cross-compilation target is the ARM CPU. When building for ARM, it isuseful to set the ABI profile. A number of pre-defined ABI profiles areavailable 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 longerproperly supported by the JDK.The JDK contains two different ports for the aarch64 platform, one is theoriginal aarch64 port from the [AArch64 Port Project](http://openjdk.java.net/projects/aarch64-port) and one is a 64-bit version ofthe Oracle contributed ARM port. When targeting aarch64, by the default theoriginal aarch64 port is used. To select the Oracle ARM 64 port, use`--with-cpu-port=arm64`. Also set the corresponding value (`aarch64` or`arm64`) to --with-abi-profile, to ensure a consistent build.### Verifying the BuildThe build will end up in a directory named like`build/linux-arm-normal-server-release`.Inside this build output directory, the `images/jdk` will contain the newlybuilt JDK, for your *target* system.Copy these folders to your *target* system. Then you can run e.g.`images/jdk/bin/java -version`.## Build PerformanceBuilding the JDK requires a lot of horsepower. Some of the build tools can beadjusted to utilize more or less of resources such as parallel threads andmemory. The `configure` script analyzes your system and selects reasonablevalues for such options based on your hardware. If you encounter resourceproblems, such as out of memory conditions, you can modify the detected valueswith: * `--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` flagto `make`. In most cases it will be ignored by the makefiles, but it can causeproblems 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 thedefault JVM arguments passed to the Boot JDK.At the end of a successful execution of `configure`, you will get a performancesummary, indicating how well the build will perform. Here you will also getperformance 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 buildtime summary at the end of the build process.### Disk SpeedIf you are using network shares, e.g. via NFS, for your source code, make surethe build directory is situated on local disk (e.g. by `ln -s/localdisk/jdk-build $JDK-SHARE/build`). The performance penalty is extremelyhigh for building on a network share; close to unusable.Also, make sure that your build tools (including Boot JDK and toolchain) islocated 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 CheckingThe use of virus checking software, especially on Windows, can *significantly*slow down building of the JDK. If possible, turn off such software, or excludethe directory containing the JDK source code from on-the-fly checking.### CcacheThe JDK build supports building with ccache when using gcc or clang. Usingccache can radically speed up compilation of native code if you often rebuildthe same sources. Your milage may vary however, so we recommend evaluating itfor yourself. To enable it, make sure it's on the path and configure with`--enable-ccache`.### Precompiled HeadersBy default, the Hotspot build uses preccompiled headers (PCH) on the toolchainswere it is properly supported (clang, gcc, and Visual Studio). Normally, thisspeeds up the build process, but in some circumstances, it can actually slowthings down.You can experiment by disabling precompiled headers using`--disable-precompiled-headers`.### Icecc / icecream[icecc/icecream](http://github.com/icecc/icecream) is a simple way to setup adistributed compiler network. If you have multiple machines available forbuilding the JDK, you can drastically cut individual build times by utilizingit.To use, setup an icecc network, and install icecc on the build machine. Thenrun `configure` using `--enable-icecc`.### Using sjavacTo speed up Java compilation, especially incremental compilations, you can trythe experimental sjavac compiler by using `--enable-sjavac`.### Building the Right TargetSelecting 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 tobuild `images` for shipping, or if your tests require it.See also [Using Fine-Grained Make Targets](#using-fine-grained-make-targets) onhow to build an even smaller subset of the product.## TroubleshootingIf your build fails, it can sometimes be difficult to pinpoint the problem orfind a proper solution.### Locating the Source of the ErrorWhen 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 SummaryTo help you, the build system will print a failure summary at the end. It lookslike 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' failedmake/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.```Let's break it down! First, the selected configuration, and the top-leveltarget you entered on the command line that caused the failure is printed.Then, between the `Output from failing command(s) repeated here` and `End ofrepeated output` the first lines of output (stdout and stderr) from the actualfailing command is repeated. In most cases, this is the error message thatcaused the build to fail. If multiple commands were failing (this can happen ina parallel build), output from all failed commands will be printed here.The path to the `failure-logs` directory is printed. In this file you will finda `<target>.log` file that contains the output from this command in itsentirety, and also a `<target>.cmd`, which contain the complete command lineused for running this command. You can re-run the failing command by executing`. <path to failure-logs>/<target>.cmd` in your shell.Another way to trace the failure is to follow the chain of make targets, fromtop-level targets to individual file targets. Between `Make failed targetsrepeated here` and `End of repeated output` the output from make showing thischain is repeated. The first failed recipe will typically contain the full pathto the file in question that failed to compile. Following lines will show atrace of make targets why we ended up trying to compile that file.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 "`***`".Note that the build failure summary will only help you if the issue was acompilation failure or similar. If the problem is more esoteric, or is due toerrors in the build machinery, you will likely get empty output logs, and `Noindication of failed target found` instead of the make target chain.#### Checking the Build Log FileThe 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`. Thismeans that it is not necessary to redirect the build output yourself if youwant to process it.You can increase the verbosity of the log file, by the `LOG` control variableto `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 commandsexecuted by make, and `trace` will show all. Beware that both these log levelswill produce a massive build log!### Fixing Unexpected Build FailuresMost of the time, the build will fail due to incorrect changes in the sourcecode.Sometimes the build can fail with no apparent changes that have caused thefailure. If this is the first time you are building the JDK on this particularcomputer, and the build fails, the problem is likely with your buildenvironment. But even if you have previously built the JDK with success, and itnow fails, your build environment might have changed (perhaps due to OSupgrades or similar). But most likely, such failures are due to problems withthe incremental rebuild.#### Problems with the Build EnvironmentMake sure your configuration is correct. Re-run `configure`, and look for anywarnings. Warnings that appear in the middle of the `configure` output is alsorepeated at the end, after the summary. The entire log is stored in`$BUILD/configure.log`.Verify that the summary at the end looks correct. Are you indeed using the BootJDK and native toolchain that you expect?By default, the JDK has a strict approach where warnings from the compiler isconsidered errors which fail the build. For very new or very old compilerversions, this can trigger new classes of warnings, which thus fails the build.Run `configure` with `--disable-warnings-as-errors` to turn of this behavior.(The warnings will still show, but not make the build fail.)#### Problems with Incremental RebuildsIncremental rebuilds mean that when you modify part of the product, only theaffected parts get rebuilt. While this works great in most cases, andsignificantly speed up the development process, from time to time complexinterdependencies will result in an incorrect build result. This is the mostcommon cause for unexpected build problems, together with inconsistenciesbetween the different Mercurial repositories in the forest.Here are a suggested list of things to try if you are having unexpected buildproblems. Each step requires more time than the one before, so try them inorder. Most issues will be solved at step 1 or 2. 1. Make sure your forest is up-to-date Run `bash get_source.sh` to make sure you have the latest version of all repositories. 2. Clean build results The simplest way to fix incremental rebuild issues is to run `make clean`. This will remove all build results, but not the configuration or any build system support artifacts. In most cases, this will solve build errors resulting from incremental build mismatches. 3. Completely clean the build directory. If this does not work, the next step is to run `make dist-clean`, or removing the build output directory (`$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 ``` 4. Re-clone the Mercurial forest Sometimes the Mercurial repositories themselves 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 forest, and re-clone it. If you have local changes, save them first to a different location using `hg export`.### Specific Build Issues#### Clock SkewIf you get an error message like this:```File 'xxx' has modification time in the future.Clock skew detected. Your build may be incomplete.```then the clock on your build machine is out of sync with the timestamps on thesource files. Other errors, apparently unrelated but in fact caused by theclock skew, can occur along with the clock skew warnings. These secondaryerrors may tend to obscure the fact that the true root cause of the problem isan out-of-sync clock.If you see these warnings, reset the clock on the build machine, run `makeclean` and restart the build.#### Out of Memory ErrorsOn Solaris, you might get an error message like this:```Trouble writing out table to disk```To solve this, increase the amount of swap space on your build machine.On Windows, you might get error messages like this:```fatal error - couldn't allocate heapcannot create ... Permission deniedspawn failed```This can be a sign of a Cygwin problem. See the information about solvingproblems in the [Cygwin](#cygwin) section. Rebooting the computer might helptemporarily.### Getting HelpIf none of the suggestions in this document helps you, or if you find what youbelieve is a bug in the build system, please contact the Build Group by sendinga mail to [build-dev@openjdk.java.net](mailto:build-dev@openjdk.java.net).Please include the relevant parts of the configure and/or build log.If you need general help or advice about developing for the JDK, you can alsocontact the Adoption Group. See the section on [Contributing to OpenJDK](#contributing-to-openjdk) for more information.## Hints and Suggestions for Advanced Users### Setting Up a Forest for Pushing Changes (defpath)To help you prepare a proper push path for a Mercurial repository, there existsa useful tool known as [defpath](http://openjdk.java.net/projects/code-tools/defpath). It will help you setup aproper push path for pushing changes to the JDK.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:```cd ~mkdir hg-extcd hg-exthg clone http://hg.openjdk.java.net/code-tools/defpathcat << EOT >> ~/.hgrc[extensions]defpath=~/hg-ext/defpath/defpath.pyEOT```You can now setup a proper push path using:```hg defpath -d -u <your OpenJDK username>```If you also have the `trees` extension installed in Mercurial, you willautomatically get a `tdefpath` command, which is even more useful. By running`hg tdefpath -du <username>` in the top repository of your forest, all reposwill get setup automatically. This is the recommended usage.### Bash CompletionThe `configure` and `make` commands tries to play nice with bash command-linecompletion (using `<tab>` or `<tab><tab>`). To use this functionality, makesure you enable completion in your `~/.bashrc` (see instructions for bash inyour operating system).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` script can get completion for options, but for this to work youneed to help `bash` on the way. The standard way of running the script, `bashconfigure`, will not be understood by bash completion. You need `configure` tobe the command to run. One way to achieve this is to add a simple helper scriptto your path:```cat << EOT > /tmp/configure#!/bin/bashif [ \$(pwd) = \$(cd \$(dirname \$0); pwd) ] ; then echo >&2 "Abort: Trying to call configure helper recursively" exit 1fibash \$PWD/configure "\$@"EOTchmod +x /tmp/configuresudo mv /tmp/configure /usr/local/bin```Now `configure --en<tab>-dt<tab>` will result in `configure --enable-dtrace`.### Using Multiple ConfigurationsYou can have multiple configurations for a single source forest. When youcreate a new configuration, run `configure --with-conf-name=<name>` to create aconfiguration with the name `<name>`. Alternatively, you can create a directoryunder `build` and run `configure` from there, e.g. `mkdir build/<name> && cdbuild/<name> && bash ../../configure`.Then you can build that configuration using `make CONF_NAME=<name>` or `makeCONF=<pattern>`, where `<pattern>` is a substring matching one or severalconfigurations, e.g. `CONF=debug`. The special empty pattern (`CONF=`) willmatch *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`.### Handling ReconfigurationsIf you update the forest and part of the configure script has changed, thebuild system will force you to re-run `configure`.Most of the time, you will be fine by running `configure` again with the samearguments as the last time, which can easily be performed by `makereconfigure`. To simplify this, you can use the `CONF_CHECK` make controlvariable, either as `make CONF_CHECK=auto`, or by setting an environmentvariable. For instance, if you add `export CONF_CHECK=auto` to your `.bashrc`file, `make` will always run `reconfigure` automatically whenever the configurescript has changed.You can also use `CONF_CHECK=ignore` to skip the check for a needed configureupdate. This might speed up the build, but comes at the risk of an incorrectbuild result. This is only recommended if you know what you're doing.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 foryour current configuration.### Using Fine-Grained Make TargetsThe default behavior for make is to create consistent and correct output, atthe expense of build speed, if necessary.If you are prepared to take some risk of an incorrect build, and know enough ofthe system to understand how things build and interact, you can speed up thebuild process considerably by instructing make to only build a portion of theproduct.#### Building Individual ModulesThe safe way to use fine-grained make targets is to use the module specificmake targets. All source code in the JDK is organized so it belongs to amodule, e.g. `java.base` or `jdk.jdwp.agent`. You can build only a specificmodule, by giving it as make target: `make jdk.jdwp.agent`. If the specifiedmodule depends on other modules (e.g. `java.base`), those modules will be builtfirst.You can also specify a set of modules, just as you can always specify a set ofmake targets: `make jdk.crypto.cryptoki jdk.crypto.ec jdk.crypto.mscapijdk.crypto.ucrypto`#### Building Individual Module PhasesThe build process for each module is divided into separate phases. Not allmodules need all phases. Which are needed depends on what kind of source codeand other artifact the module consists of. The phases are: * `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) * `rmic` (Run the `rmic` tool)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`.Note that some phases may depend on others, e.g. `java` depends on `gensrc` (ifpresent). Make will build all needed prerequisites before building therequested phase.#### Skipping the Dependency CheckWhen using an iterative development style with frequent quick rebuilds, thedependency check made by make can take up a significant portion of the timespent on the rebuild. In such cases, it can be useful to bypass the dependencycheck in make.> **Note that if used incorrectly, this can lead to a broken build!**To achieve this, append `-only` to the build target. For instance, `makejdk.jdwp.agent-java-only` will *only* build the `java` phase of the`jdk.jdwp.agent` module. If the required dependencies are not present, thebuild can fail. On the other hand, the execution time measures in milliseconds.A useful pattern is to build the first time normally (e.g. `makejdk.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 modulein the JDK, then you need to rebuild all those files whenever a single file haschanged. (This inefficiency will hopefully be addressed in JDK 10.)As a hack, you can use the make control variable `JDK_FILTER` to specify apattern that will be used to limit the set of files being recompiled. Forinstance, `make java.base JDK_FILTER=javax/crypto` (or, to combine methods,`make java.base-java-only JDK_FILTER=javax/crypto`) will limit the compilationto files in the `javax.crypto` package.### Learn About MercurialTo become an efficient JDK developer, it is recommended that you invest inlearning Mercurial properly. Here are some links that can get you started: * [Mercurial for git users](http://www.mercurial-scm.org/wiki/GitConcepts) * [The official Mercurial tutorial](http://www.mercurial-scm.org/wiki/Tutorial) * [hg init](http://hginit.com/) * [Mercurial: The Definitive Guide](http://hgbook.red-bean.com/read/)## Understanding the Build SystemThis section will give you a more technical description on the details of thebuild system.### ConfigurationsThe build system expects to find one or more configuration. These aretechnically defined by the `spec.gmk` in a subdirectory to the `build`subdirectory. The `spec.gmk` file is generated by `configure`, and contains inprinciple 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 isused under the hood by the build system.### Build Output StructureThe build output for a configuration will end up in `build/<configurationname>`, which we refer to as `$BUILD` in this document. The `$BUILD` directorycontains the following important directories:```buildtools/configure-support/hotspot/images/jdk/make-support/support/test-results/test-support/```This is what they are used for: * `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.### FixpathWindows path typically look like `C:\User\foo`, while Unix paths look like`/home/foo`. Tools with roots from Unix often experience issues related to thismismatch when running on Windows.In the JDK build, we always use Unix paths internally, and only just beforecalling a tool that does not understand Unix paths do we convert them toWindows paths.This conversion is done by the `fixpath` tool, which is a small wrapper thatmodifies unix-style paths to Windows-style paths in command lines. Fixpath iscompiled automatically by `configure`.### Native Debug SymbolsNative libraries and executables can have debug symbol (and other debuginformation) associated with them. How this works is very much platformdependent, but a common problem is that debug symbol information takes a lot ofdisk space, but is rarely needed by the end user.The JDK supports different methods on how to handle debug symbols. Themethod used is selected by `--with-native-debug-symbols`, and available methodsare `none`, `internal`, `external`, `zipped`. * `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.When building for distribution, `zipped` is a good solution. Binaries builtwith `internal` is suitable for use by developers, since they facilitatedebugging, but should be stripped before distributed to end users.### Autoconf DetailsThe `configure` script is based on the autoconf framework, but in some detailsdeviate from a normal autoconf `configure` script.The `configure` script in the top level directory of the JDK is just a thinwrapper 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 thegeneration of the runnable script, the `configure` script also providesfunctionality that is not easily expressed in the normal Autoconf framework. Aspart of this functionality, the generated script is called.The build system will detect if the Autoconf source files have changed, andwill trigger a regeneration of the generated script if needed. You can alsomanually request such an update by `bash configure autogen`.In previous versions of the JDK, the generated script was checked in at`make/autoconf/generated-configure.sh`. This is no longer the case.### Developing the Build System ItselfThis section contains a few remarks about how to develop for the build systemitself. It is not relevant if you are only making changes in the product sourcecode.While technically using `make`, the make source files of the JDK does notresemble most other Makefiles. Instead of listing specific targets and actions(perhaps using patterns), the basic modus operandi is to call a high-levelfunction (or properly, macro) from the API in `make/common`. For instance, tocompile all classes in the `jdk.internal.foo` package in the `jdk.foo` module,a call like this would be made:```$(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, \))```By encapsulating and expressing the high-level knowledge of *what* should bedone, rather than *how* it should be done (as is normal in Makefiles), we canbuild a much more powerful and flexible build system.Correct dependency tracking is paramount. Sloppy dependency tracking will leadto improper parallelization, or worse, race conditions.To test for/debug race conditions, try running `make JOBS=1` and `makeJOBS=100` and see if it makes any difference. (It shouldn't).To compare the output of two different builds and see if, and how, they differ,run `$BUILD1/compare.sh -o $BUILD2`, where `$BUILD1` and `$BUILD2` are the twobuilds you want to compare.To automatically build two consecutive versions and compare them, use`COMPARE_BUILD`. The value of `COMPARE_BUILD` is a set of variable=valueassignments, like this:```make COMPARE_BUILD=CONF=--enable-new-hotspot-feature:MAKE=hotspot```See `make/InitSupport.gmk` for details on how to use `COMPARE_BUILD`.To analyze build performance, run with `LOG=trace` and check `$BUILD/build-trace-time.log`.Use `JOBS=1` to avoid parallelism.Please check that you adhere to the [Code Conventions for the Build System](http://openjdk.java.net/groups/build/doc/code-conventions.html) beforesubmitting patches.## Contributing to the JDKSo, now you've built your JDK, and made your first patch, and want tocontribute it back to the OpenJDK Community.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 askyou to follow our rules and guidelines to be able to accept your contribution.The official place to start is the ['How to contribute' page](http://openjdk.java.net/contribute/). There is also an official (but somewhatoutdated and skimpy on details) [Developer's Guide](http://openjdk.java.net/guide/).If this seems overwhelming to you, the Adoption Group is there to help you! Agood place to start is their ['New Contributor' page](https://wiki.openjdk.java.net/display/Adoption/New+Contributor), or startreading the comprehensive [Getting Started Kit](https://adoptopenjdk.gitbooks.io/adoptopenjdk-getting-started-kit/en/). TheAdoption Group will also happily answer any questions you have aboutcontributing. Contact them by [mail](http://mail.openjdk.java.net/mailman/listinfo/adoption-discuss) or [IRC](http://openjdk.java.net/irc/).---# Override styles from the base CSS file that are not ideal for this document.header-includes: - '<style type="text/css">pre, code, tt { color: #1d6ae5; }</style>'---