1 % Building OpenJDK 2 3 ## TL;DR (Instructions for the Impatient) 4 5 If you are eager to try out building OpenJDK, these simple steps works most of 6 the time. They assume that you have installed Mercurial (and Cygwin if running 7 on Windows) and cloned the top-level OpenJDK repository that you want to build. 8 9 1. [Get the complete source code](#getting-the-source-code): \ 10 `hg clone http://hg.openjdk.java.net/jdk/jdk` 11 12 2. [Run configure](#running-configure): \ 13 `bash configure` 14 15 If `configure` fails due to missing dependencies (to either the 16 [toolchain](#native-compiler-toolchain-requirements), [build tools]( 17 #build-tools-requirements), [external libraries]( 18 #external-library-requirements) or the [boot JDK](#boot-jdk-requirements)), 19 most of the time it prints a suggestion on how to resolve the situation on 20 your platform. Follow the instructions, and try running `bash configure` 21 again. 22 23 3. [Run make](#running-make): \ 24 `make images` 25 26 4. Verify your newly built JDK: \ 27 `./build/*/images/jdk/bin/java -version` 28 29 5. [Run basic tests](##running-tests): \ 30 `make run-test-tier1` 31 32 If any of these steps failed, or if you want to know more about build 33 requirements or build functionality, please continue reading this document. 34 35 ## Introduction 36 37 OpenJDK is a complex software project. Building it requires a certain amount of 38 technical expertise, a fair number of dependencies on external software, and 39 reasonably powerful hardware. 40 41 If you just want to use OpenJDK and not build it yourself, this document is not 42 for you. See for instance [OpenJDK installation]( 43 http://openjdk.java.net/install) for some methods of installing a prebuilt 44 OpenJDK. 45 46 ## Getting the Source Code 47 48 Make sure you are getting the correct version. As of JDK 10, the source is no 49 longer split into separate repositories so you only need to clone one single 50 repository. At the [OpenJDK Mercurial server](http://hg.openjdk.java.net/) you 51 can see a list of all available forests. If you want to build an older version, 52 e.g. JDK 8, it is recommended that you get the `jdk8u` forest, which contains 53 incremental updates, instead of the `jdk8` forest, which was frozen at JDK 8 GA. 54 55 If you are new to Mercurial, a good place to start is the [Mercurial Beginner's 56 Guide](http://www.mercurial-scm.org/guide). The rest of this document assumes a 57 working knowledge of Mercurial. 58 59 ### Special Considerations 60 61 For a smooth building experience, it is recommended that you follow these rules 62 on where and how to check out the source code. 63 64 * Do not check out the source code in a path which contains spaces. Chances 65 are the build will not work. This is most likely to be an issue on Windows 66 systems. 67 68 * Do not check out the source code in a path which has a very long name or is 69 nested many levels deep. Chances are you will hit an OS limitation during 70 the build. 71 72 * Put the source code on a local disk, not a network share. If possible, use 73 an SSD. The build process is very disk intensive, and having slow disk 74 access will significantly increase build times. If you need to use a 75 network share for the source code, see below for suggestions on how to keep 76 the build artifacts on a local disk. 77 78 * On Windows, extra care must be taken to make sure the [Cygwin](#cygwin) 79 environment is consistent. It is recommended that you follow this 80 procedure: 81 82 * Create the directory that is going to contain the top directory of the 83 OpenJDK clone by using the `mkdir` command in the Cygwin bash shell. 84 That is, do *not* create it using Windows Explorer. This will ensure 85 that it will have proper Cygwin attributes, and that it's children will 86 inherit those attributes. 87 88 * Do not put the OpenJDK clone in a path under your Cygwin home 89 directory. This is especially important if your user name contains 90 spaces and/or mixed upper and lower case letters. 91 92 * Clone the OpenJDK repository using the Cygwin command line `hg` client 93 as instructed in this document. That is, do *not* use another Mercurial 94 client such as TortoiseHg. 95 96 Failure to follow this procedure might result in hard-to-debug build 97 problems. 98 99 ## Build Hardware Requirements 100 101 OpenJDK is a massive project, and require machines ranging from decent to 102 powerful to be able to build in a reasonable amount of time, or to be able to 103 complete a build at all. 104 105 We *strongly* recommend usage of an SSD disk for the build, since disk speed is 106 one of the limiting factors for build performance. 107 108 ### Building on x86 109 110 At a minimum, a machine with 2-4 cores is advisable, as well as 2-4 GB of RAM. 111 (The more cores to use, the more memory you need.) At least 6 GB of free disk 112 space is required (8 GB minimum for building on Solaris). 113 114 Even for 32-bit builds, it is recommended to use a 64-bit build machine, and 115 instead create a 32-bit target using `--with-target-bits=32`. 116 117 ### Building on sparc 118 119 At a minimum, a machine with 4 cores is advisable, as well as 4 GB of RAM. (The 120 more cores to use, the more memory you need.) At least 8 GB of free disk space 121 is required. 122 123 ### Building on arm/aarch64 124 125 This is not recommended. Instead, see the section on [Cross-compiling]( 126 #cross-compiling). 127 128 ## Operating System Requirements 129 130 The mainline OpenJDK project supports Linux, Solaris, macOS, AIX and Windows. 131 Support for other operating system, e.g. BSD, exists in separate "port" 132 projects. 133 134 In general, OpenJDK can be built on a wide range of versions of these operating 135 systems, but the further you deviate from what is tested on a daily basis, the 136 more likely you are to run into problems. 137 138 This table lists the OS versions used by Oracle when building JDK 9. Such 139 information is always subject to change, but this table is up to date at the 140 time of writing. 141 142 Operating system Vendor/version used 143 ----------------- ------------------------------------------------------- 144 Linux Oracle Enterprise Linux 6.4 / 7.1 (using kernel 3.8.13) 145 Solaris Solaris 11.1 SRU 21.4.1 / 11.2 SRU 5.5 146 macOS Mac OS X 10.9 (Mavericks) / 10.10 (Yosemite) 147 Windows Windows Server 2012 R2 148 149 The double version numbers for Linux, Solaris and macOS is due to the hybrid 150 model used at Oracle, where header files and external libraries from an older 151 version is used when building on a more modern version of the OS. 152 153 The Build Group has a wiki page with [Supported Build Platforms]( 154 https://wiki.openjdk.java.net/display/Build/Supported+Build+Platforms). From 155 time to time, this is updated by the community to list successes or failures of 156 building on different platforms. 157 158 ### Windows 159 160 Windows XP is not a supported platform, but all newer Windows should be able to 161 build OpenJDK. 162 163 On Windows, it is important that you pay attention to the instructions in the 164 [Special Considerations](#special-considerations). 165 166 Windows is the only non-POSIX OS supported by OpenJDK, and as such, requires 167 some extra care. A POSIX support layer is required to build on Windows. For 168 OpenJDK 9, the only supported such layer is Cygwin. (Msys is no longer 169 supported due to a too old bash; msys2 and the new Windows Subsystem for Linux 170 (WSL) would likely be possible to support in a future version but that would 171 require a community effort to implement.) 172 173 Internally in the build system, all paths are represented as Unix-style paths, 174 e.g. `/cygdrive/c/hg/jdk9/Makefile` rather than `C:\hg\jdk9\Makefile`. This 175 rule also applies to input to the build system, e.g. in arguments to 176 `configure`. So, use `--with-freetype=/cygdrive/c/freetype` rather than 177 `--with-freetype=c:\freetype`. For details on this conversion, see the section 178 on [Fixpath](#fixpath). 179 180 #### Cygwin 181 182 A functioning [Cygwin](http://www.cygwin.com/) environment is thus required for 183 building OpenJDK on Windows. If you have a 64-bit OS, we strongly recommend 184 using the 64-bit version of Cygwin. 185 186 **Note:** Cygwin has a model of continuously updating all packages without any 187 easy way to install or revert to a specific version of a package. This means 188 that whenever you add or update a package in Cygwin, you might (inadvertently) 189 update tools that are used by the OpenJDK build process, and that can cause 190 unexpected build problems. 191 192 OpenJDK requires GNU Make 4.0 or greater on Windows. This is usually not a 193 problem, since Cygwin currently only distributes GNU Make at a version above 194 4.0. 195 196 Apart from the basic Cygwin installation, the following packages must also be 197 installed: 198 199 * `autoconf` 200 * `make` 201 * `zip` 202 * `unzip` 203 204 Often, you can install these packages using the following command line: 205 ``` 206 <path to Cygwin setup>/setup-x86_64 -q -P autoconf -P make -P unzip -P zip 207 ``` 208 209 Unfortunately, Cygwin can be unreliable in certain circumstances. If you 210 experience build tool crashes or strange issues when building on Windows, 211 please check the Cygwin FAQ on the ["BLODA" list]( 212 https://cygwin.com/faq/faq.html#faq.using.bloda) and the section on [fork() 213 failures](https://cygwin.com/faq/faq.html#faq.using.fixing-fork-failures). 214 215 ### Solaris 216 217 See `make/devkit/solaris11.1-package-list.txt` for a list of recommended 218 packages to install when building on Solaris. The versions specified in this 219 list is the versions used by the daily builds at Oracle, and is likely to work 220 properly. 221 222 Older versions of Solaris shipped a broken version of `objcopy`. At least 223 version 2.21.1 is needed, which is provided by Solaris 11 Update 1. Objcopy is 224 needed if you want to have external debug symbols. Please make sure you are 225 using at least version 2.21.1 of objcopy, or that you disable external debug 226 symbols. 227 228 ### macOS 229 230 Apple is using a quite aggressive scheme of pushing OS updates, and coupling 231 these updates with required updates of Xcode. Unfortunately, this makes it 232 difficult for a project like OpenJDK to keep pace with a continuously updated 233 machine running macOS. See the section on [Apple Xcode](#apple-xcode) on some 234 strategies to deal with this. 235 236 It is recommended that you use at least Mac OS X 10.9 (Mavericks). At the time 237 of writing, OpenJDK has been successfully compiled on macOS versions up to 238 10.12.5 (Sierra), using XCode 8.3.2 and `--disable-warnings-as-errors`. 239 240 The standard macOS environment contains the basic tooling needed to build, but 241 for external libraries a package manager is recommended. OpenJDK uses 242 [homebrew](https://brew.sh/) in the examples, but feel free to use whatever 243 manager you want (or none). 244 245 ### Linux 246 247 It is often not much problem to build OpenJDK on Linux. The only general advice 248 is to try to use the compilers, external libraries and header files as provided 249 by your distribution. 250 251 The basic tooling is provided as part of the core operating system, but you 252 will most likely need to install developer packages. 253 254 For apt-based distributions (Debian, Ubuntu, etc), try this: 255 ``` 256 sudo apt-get install build-essential 257 ``` 258 259 For rpm-based distributions (Fedora, Red Hat, etc), try this: 260 ``` 261 sudo yum groupinstall "Development Tools" 262 ``` 263 264 ### AIX 265 266 The regular builds by SAP is using AIX version 7.1, but AIX 5.3 is also 267 supported. See the [OpenJDK PowerPC Port Status Page]( 268 http://cr.openjdk.java.net/~simonis/ppc-aix-port) for details. 269 270 ## Native Compiler (Toolchain) Requirements 271 272 Large portions of OpenJDK consists of native code, that needs to be compiled to 273 be able to run on the target platform. In theory, toolchain and operating 274 system should be independent factors, but in practice there's more or less a 275 one-to-one correlation between target operating system and toolchain. 276 277 Operating system Supported toolchain 278 ------------------ ------------------------- 279 Linux gcc, clang 280 macOS Apple Xcode (using clang) 281 Solaris Oracle Solaris Studio 282 AIX IBM XL C/C++ 283 Windows Microsoft Visual Studio 284 285 Please see the individual sections on the toolchains for version 286 recommendations. As a reference, these versions of the toolchains are used, at 287 the time of writing, by Oracle for the daily builds of OpenJDK. It should be 288 possible to compile OpenJDK with both older and newer versions, but the closer 289 you stay to this list, the more likely you are to compile successfully without 290 issues. 291 292 Operating system Toolchain version 293 ------------------ ------------------------------------------------------- 294 Linux gcc 4.9.2 295 macOS Apple Xcode 6.3 (using clang 6.1.0) 296 Solaris Oracle Solaris Studio 12.4 (with compiler version 5.13) 297 Windows Microsoft Visual Studio 2013 update 4 298 299 ### gcc 300 301 The minimum accepted version of gcc is 4.7. Older versions will generate a warning 302 by `configure` and are unlikely to work. 303 304 OpenJDK 9 includes patches that should allow gcc 6 to compile, but this should 305 be considered experimental. 306 307 In general, any version between these two should be usable. 308 309 ### clang 310 311 The minimum accepted version of clang is 3.2. Older versions will not be 312 accepted by `configure`. 313 314 To use clang instead of gcc on Linux, use `--with-toolchain-type=clang`. 315 316 ### Apple Xcode 317 318 The oldest supported version of Xcode is 5. 319 320 You will need the Xcode command lines developers tools to be able to build 321 OpenJDK. (Actually, *only* the command lines tools are needed, not the IDE.) 322 The simplest way to install these is to run: 323 ``` 324 xcode-select --install 325 ``` 326 327 It is advisable to keep an older version of Xcode for building OpenJDK when 328 updating Xcode. This [blog page]( 329 http://iosdevelopertips.com/xcode/install-multiple-versions-of-xcode.html) has 330 good suggestions on managing multiple Xcode versions. To use a specific version 331 of Xcode, use `xcode-select -s` before running `configure`, or use 332 `--with-toolchain-path` to point to the version of Xcode to use, e.g. 333 `configure --with-toolchain-path=/Applications/Xcode5.app/Contents/Developer/usr/bin` 334 335 If you have recently (inadvertently) updated your OS and/or Xcode version, and 336 OpenJDK can no longer be built, please see the section on [Problems with the 337 Build Environment](#problems-with-the-build-environment), and [Getting 338 Help](#getting-help) to find out if there are any recent, non-merged patches 339 available for this update. 340 341 ### Oracle Solaris Studio 342 343 The minimum accepted version of the Solaris Studio compilers is 5.13 344 (corresponding to Solaris Studio 12.4). Older versions will not be accepted by 345 configure. 346 347 The Solaris Studio installation should contain at least these packages: 348 349 Package Version 350 -------------------------------------------------- ------------- 351 developer/solarisstudio-124/backend 12.4-1.0.6.0 352 developer/solarisstudio-124/c++ 12.4-1.0.10.0 353 developer/solarisstudio-124/cc 12.4-1.0.4.0 354 developer/solarisstudio-124/library/c++-libs 12.4-1.0.10.0 355 developer/solarisstudio-124/library/math-libs 12.4-1.0.0.1 356 developer/solarisstudio-124/library/studio-gccrt 12.4-1.0.0.1 357 developer/solarisstudio-124/studio-common 12.4-1.0.0.1 358 developer/solarisstudio-124/studio-ja 12.4-1.0.0.1 359 developer/solarisstudio-124/studio-legal 12.4-1.0.0.1 360 developer/solarisstudio-124/studio-zhCN 12.4-1.0.0.1 361 362 Compiling with Solaris Studio can sometimes be finicky. This is the exact 363 version used by Oracle, which worked correctly at the time of writing: 364 ``` 365 $ cc -V 366 cc: Sun C 5.13 SunOS_i386 2014/10/20 367 $ CC -V 368 CC: Sun C++ 5.13 SunOS_i386 151846-10 2015/10/30 369 ``` 370 371 ### Microsoft Visual Studio 372 373 The minimum accepted version of Visual Studio is 2010. Older versions will not 374 be accepted by `configure`. The maximum accepted version of Visual Studio is 375 2013. 376 377 If you have multiple versions of Visual Studio installed, `configure` will by 378 default pick the latest. You can request a specific version to be used by 379 setting `--with-toolchain-version`, e.g. `--with-toolchain-version=2010`. 380 381 If you get `LINK: fatal error LNK1123: failure during conversion to COFF: file 382 invalid` when building using Visual Studio 2010, you have encountered 383 [KB2757355](http://support.microsoft.com/kb/2757355), a bug triggered by a 384 specific installation order. However, the solution suggested by the KB article 385 does not always resolve the problem. See [this stackoverflow discussion]( 386 https://stackoverflow.com/questions/10888391) for other suggestions. 387 388 ### IBM XL C/C++ 389 390 The regular builds by SAP is using version 12.1, described as `IBM XL C/C++ for 391 AIX, V12.1 (5765-J02, 5725-C72) Version: 12.01.0000.0017`. 392 393 See the [OpenJDK PowerPC Port Status Page]( 394 http://cr.openjdk.java.net/~simonis/ppc-aix-port) for details. 395 396 ## Boot JDK Requirements 397 398 Paradoxically, building OpenJDK requires a pre-existing JDK. This is called the 399 "boot JDK". The boot JDK does not have to be OpenJDK, though. If you are 400 porting OpenJDK to a new platform, chances are that there already exists 401 another JDK for that platform that is usable as boot JDK. 402 403 The rule of thumb is that the boot JDK for building JDK major version *N* 404 should be an JDK of major version *N-1*, so for building JDK 9 a JDK 8 would be 405 suitable as boot JDK. However, OpenJDK should be able to "build itself", so an 406 up-to-date build of the current OpenJDK source is an acceptable alternative. If 407 you are following the *N-1* rule, make sure you got the latest update version, 408 since JDK 8 GA might not be able to build JDK 9 on all platforms. 409 410 If the Boot JDK is not automatically detected, or the wrong JDK is picked, use 411 `--with-boot-jdk` to point to the JDK to use. 412 413 ### JDK 8 on Linux 414 415 On apt-based distros (like Debian and Ubuntu), `sudo apt-get install 416 openjdk-8-jdk` is typically enough to install OpenJDK 8. On rpm-based distros 417 (like Fedora and Red Hat), try `sudo yum install java-1.8.0-openjdk-devel`. 418 419 ### JDK 8 on Windows 420 421 No pre-compiled binaries of OpenJDK 8 are readily available for Windows at the 422 time of writing. An alternative is to download the [Oracle JDK]( 423 http://www.oracle.com/technetwork/java/javase/downloads). Another is the [Adopt 424 OpenJDK Project](https://adoptopenjdk.net/), which publishes experimental 425 prebuilt binaries for Windows. 426 427 ### JDK 8 on macOS 428 429 No pre-compiled binaries of OpenJDK 8 are readily available for macOS at the 430 time of writing. An alternative is to download the [Oracle JDK]( 431 http://www.oracle.com/technetwork/java/javase/downloads), or to install it 432 using `brew cask install java`. Another option is the [Adopt OpenJDK Project]( 433 https://adoptopenjdk.net/), which publishes experimental prebuilt binaries for 434 macOS. 435 436 ### JDK 8 on AIX 437 438 No pre-compiled binaries of OpenJDK 8 are readily available for AIX at the 439 time of writing. A starting point for working with OpenJDK on AIX is 440 the [PowerPC/AIX Port Project](http://openjdk.java.net/projects/ppc-aix-port/). 441 442 ## External Library Requirements 443 444 Different platforms require different external libraries. In general, libraries 445 are not optional - that is, they are either required or not used. 446 447 If a required library is not detected by `configure`, you need to provide the 448 path to it. There are two forms of the `configure` arguments to point to an 449 external library: `--with-<LIB>=<path>` or `--with-<LIB>-include=<path to 450 include> --with-<LIB>-lib=<path to lib>`. The first variant is more concise, 451 but require the include files an library files to reside in a default hierarchy 452 under this directory. In most cases, it works fine. 453 454 As a fallback, the second version allows you to point to the include directory 455 and the lib directory separately. 456 457 ### FreeType 458 459 FreeType2 from [The FreeType Project](http://www.freetype.org/) is required on 460 all platforms. At least version 2.3 is required. 461 462 * To install on an apt-based Linux, try running `sudo apt-get install 463 libcups2-dev`. 464 * To install on an rpm-based Linux, try running `sudo yum install 465 cups-devel`. 466 * To install on Solaris, try running `pkg install system/library/freetype-2`. 467 * To install on macOS, try running `brew install freetype`. 468 * To install on Windows, see [below](#building-freetype-on-windows). 469 470 Use `--with-freetype=<path>` if `configure` does not properly locate your 471 FreeType files. 472 473 #### Building FreeType on Windows 474 475 On Windows, there is no readily available compiled version of FreeType. OpenJDK 476 can help you compile FreeType from source. Download the FreeType sources and 477 unpack them into an arbitrary directory: 478 479 ``` 480 wget http://download.savannah.gnu.org/releases/freetype/freetype-2.5.3.tar.gz 481 tar -xzf freetype-2.5.3.tar.gz 482 ``` 483 484 Then run `configure` with `--with-freetype-src=<freetype_src>`. This will 485 automatically build the freetype library into `<freetype_src>/lib64` for 64-bit 486 builds or into `<freetype_src>/lib32` for 32-bit builds. Afterwards you can 487 always use `--with-freetype-include=<freetype_src>/include` and 488 `--with-freetype-lib=<freetype_src>/lib[32|64]` for other builds. 489 490 Alternatively you can unpack the sources like this to use the default 491 directory: 492 493 ``` 494 tar --one-top-level=$HOME/freetype --strip-components=1 -xzf freetype-2.5.3.tar.gz 495 ``` 496 497 ### CUPS 498 499 CUPS, [Common UNIX Printing System](http://www.cups.org) header files are 500 required on all platforms, except Windows. Often these files are provided by 501 your operating system. 502 503 * To install on an apt-based Linux, try running `sudo apt-get install 504 libcups2-dev`. 505 * To install on an rpm-based Linux, try running `sudo yum install 506 cups-devel`. 507 * To install on Solaris, try running `pkg install print/cups`. 508 509 Use `--with-cups=<path>` if `configure` does not properly locate your CUPS 510 files. 511 512 ### X11 513 514 Certain [X11](http://www.x.org/) libraries and include files are required on 515 Linux and Solaris. 516 517 * To install on an apt-based Linux, try running `sudo apt-get install 518 libx11-dev libxext-dev libxrender-dev libxtst-dev libxt-dev`. 519 * To install on an rpm-based Linux, try running `sudo yum install 520 libXtst-devel libXt-devel libXrender-devel libXi-devel`. 521 * To install on Solaris, try running `pkg install x11/header/x11-protocols 522 x11/library/libice x11/library/libpthread-stubs x11/library/libsm 523 x11/library/libx11 x11/library/libxau x11/library/libxcb 524 x11/library/libxdmcp x11/library/libxevie x11/library/libxext 525 x11/library/libxrender x11/library/libxscrnsaver x11/library/libxtst 526 x11/library/toolkit/libxt`. 527 528 Use `--with-x=<path>` if `configure` does not properly locate your X11 files. 529 530 ### ALSA 531 532 ALSA, [Advanced Linux Sound Architecture](https://www.alsa-project.org/) is 533 required on Linux. At least version 0.9.1 of ALSA is required. 534 535 * To install on an apt-based Linux, try running `sudo apt-get install 536 libasound2-dev`. 537 * To install on an rpm-based Linux, try running `sudo yum install 538 alsa-lib-devel`. 539 540 Use `--with-alsa=<path>` if `configure` does not properly locate your ALSA 541 files. 542 543 ### libffi 544 545 libffi, the [Portable Foreign Function Interface Library]( 546 http://sourceware.org/libffi) is required when building the Zero version of 547 Hotspot. 548 549 * To install on an apt-based Linux, try running `sudo apt-get install 550 libffi-dev`. 551 * To install on an rpm-based Linux, try running `sudo yum install 552 libffi-devel`. 553 554 Use `--with-libffi=<path>` if `configure` does not properly locate your libffi 555 files. 556 557 ## Build Tools Requirements 558 559 ### Autoconf 560 561 OpenJDK requires [Autoconf](http://www.gnu.org/software/autoconf) on all 562 platforms. At least version 2.69 is required. 563 564 * To install on an apt-based Linux, try running `sudo apt-get install 565 autoconf`. 566 * To install on an rpm-based Linux, try running `sudo yum install 567 autoconf`. 568 * To install on macOS, try running `brew install autoconf`. 569 * To install on Windows, try running `<path to Cygwin setup>/setup-x86_64 -q 570 -P autoconf`. 571 572 If `configure` has problems locating your installation of autoconf, you can 573 specify it using the `AUTOCONF` environment variable, like this: 574 575 ``` 576 AUTOCONF=<path to autoconf> configure ... 577 ``` 578 579 ### GNU Make 580 581 OpenJDK requires [GNU Make](http://www.gnu.org/software/make). No other flavors 582 of make are supported. 583 584 At least version 3.81 of GNU Make must be used. For distributions supporting 585 GNU Make 4.0 or above, we strongly recommend it. GNU Make 4.0 contains useful 586 functionality to handle parallel building (supported by `--with-output-sync`) 587 and speed and stability improvements. 588 589 Note that `configure` locates and verifies a properly functioning version of 590 `make` and stores the path to this `make` binary in the configuration. If you 591 start a build using `make` on the command line, you will be using the version 592 of make found first in your `PATH`, and not necessarily the one stored in the 593 configuration. This initial make will be used as "bootstrap make", and in a 594 second stage, the make located by `configure` will be called. Normally, this 595 will present no issues, but if you have a very old `make`, or a non-GNU Make 596 `make` in your path, this might cause issues. 597 598 If you want to override the default make found by `configure`, use the `MAKE` 599 configure variable, e.g. `configure MAKE=/opt/gnu/make`. 600 601 On Solaris, it is common to call the GNU version of make by using `gmake`. 602 603 ### GNU Bash 604 605 OpenJDK requires [GNU Bash](http://www.gnu.org/software/bash). No other shells 606 are supported. 607 608 At least version 3.2 of GNU Bash must be used. 609 610 ## Running Configure 611 612 To build OpenJDK, you need a "configuration", which consists of a directory 613 where to store the build output, coupled with information about the platform, 614 the specific build machine, and choices that affect how OpenJDK is built. 615 616 The configuration is created by the `configure` script. The basic invocation of 617 the `configure` script looks like this: 618 619 ``` 620 bash configure [options] 621 ``` 622 623 This will create an output directory containing the configuration and setup an 624 area for the build result. This directory typically looks like 625 `build/linux-x64-normal-server-release`, but the actual name depends on your 626 specific configuration. (It can also be set directly, see [Using Multiple 627 Configurations](#using-multiple-configurations)). This directory is referred to 628 as `$BUILD` in this documentation. 629 630 `configure` will try to figure out what system you are running on and where all 631 necessary build components are. If you have all prerequisites for building 632 installed, it should find everything. If it fails to detect any component 633 automatically, it will exit and inform you about the problem. 634 635 Some command line examples: 636 637 * Create a 32-bit build for Windows with FreeType2 in `C:\freetype-i586`: 638 ``` 639 bash configure --with-freetype=/cygdrive/c/freetype-i586 --with-target-bits=32 640 ``` 641 642 * Create a debug build with the `server` JVM and DTrace enabled: 643 ``` 644 bash configure --enable-debug --with-jvm-variants=server --enable-dtrace 645 ``` 646 647 ### Common Configure Arguments 648 649 Here follows some of the most common and important `configure` argument. 650 651 To get up-to-date information on *all* available `configure` argument, please 652 run: 653 ``` 654 bash configure --help 655 ``` 656 657 (Note that this help text also include general autoconf options, like 658 `--dvidir`, that is not relevant to OpenJDK. To list only OpenJDK specific 659 features, use `bash configure --help=short` instead.) 660 661 #### Configure Arguments for Tailoring the Build 662 663 * `--enable-debug` - Set the debug level to `fastdebug` (this is a shorthand 664 for `--with-debug-level=fastdebug`) 665 * `--with-debug-level=<level>` - Set the debug level, which can be `release`, 666 `fastdebug`, `slowdebug` or `optimized`. Default is `release`. `optimized` 667 is variant of `release` with additional Hotspot debug code. 668 * `--with-native-debug-symbols=<method>` - Specify if and how native debug 669 symbols should be built. Available methods are `none`, `internal`, 670 `external`, `zipped`. Default behavior depends on platform. See [Native 671 Debug Symbols](#native-debug-symbols) for more details. 672 * `--with-version-string=<string>` - Specify the version string this build 673 will be identified with. 674 * `--with-version-<part>=<value>` - A group of options, where `<part>` can be 675 any of `pre`, `opt`, `build`, `major`, `minor`, `security` or `patch`. Use 676 these options to modify just the corresponding part of the version string 677 from the default, or the value provided by `--with-version-string`. 678 * `--with-jvm-variants=<variant>[,<variant>...]` - Build the specified variant 679 (or variants) of Hotspot. Valid variants are: `server`, `client`, 680 `minimal`, `core`, `zero`, `custom`. Note that not all 681 variants are possible to combine in a single build. 682 * `--with-jvm-features=<feature>[,<feature>...]` - Use the specified JVM 683 features when building Hotspot. The list of features will be enabled on top 684 of the default list. For the `custom` JVM variant, this default list is 685 empty. A complete list of available JVM features can be found using `bash 686 configure --help`. 687 * `--with-target-bits=<bits>` - Create a target binary suitable for running 688 on a `<bits>` platform. Use this to create 32-bit output on a 64-bit build 689 platform, instead of doing a full cross-compile. (This is known as a 690 *reduced* build.) 691 692 #### Configure Arguments for Native Compilation 693 694 * `--with-devkit=<path>` - Use this devkit for compilers, tools and resources 695 * `--with-sysroot=<path>` - Use this directory as sysroot 696 * `--with-extra-path=<path>[;<path>]` - Prepend these directories to the 697 default path when searching for all kinds of binaries 698 * `--with-toolchain-path=<path>[;<path>]` - Prepend these directories when 699 searching for toolchain binaries (compilers etc) 700 * `--with-extra-cflags=<flags>` - Append these flags when compiling JDK C 701 files 702 * `--with-extra-cxxflags=<flags>` - Append these flags when compiling JDK C++ 703 files 704 * `--with-extra-ldflags=<flags>` - Append these flags when linking JDK 705 libraries 706 707 #### Configure Arguments for External Dependencies 708 709 * `--with-boot-jdk=<path>` - Set the path to the [Boot JDK]( 710 #boot-jdk-requirements) 711 * `--with-freetype=<path>` - Set the path to [FreeType](#freetype) 712 * `--with-cups=<path>` - Set the path to [CUPS](#cups) 713 * `--with-x=<path>` - Set the path to [X11](#x11) 714 * `--with-alsa=<path>` - Set the path to [ALSA](#alsa) 715 * `--with-libffi=<path>` - Set the path to [libffi](#libffi) 716 * `--with-jtreg=<path>` - Set the path to JTReg. See [Running Tests]( 717 #running-tests) 718 719 Certain third-party libraries used by OpenJDK (libjpeg, giflib, libpng, lcms 720 and zlib) are included in the OpenJDK repository. The default behavior of the 721 OpenJDK build is to use this version of these libraries, but they might be 722 replaced by an external version. To do so, specify `system` as the `<source>` 723 option in these arguments. (The default is `bundled`). 724 725 * `--with-libjpeg=<source>` - Use the specified source for libjpeg 726 * `--with-giflib=<source>` - Use the specified source for giflib 727 * `--with-libpng=<source>` - Use the specified source for libpng 728 * `--with-lcms=<source>` - Use the specified source for lcms 729 * `--with-zlib=<source>` - Use the specified source for zlib 730 731 On Linux, it is possible to select either static or dynamic linking of the C++ 732 runtime. The default is static linking, with dynamic linking as fallback if the 733 static library is not found. 734 735 * `--with-stdc++lib=<method>` - Use the specified method (`static`, `dynamic` 736 or `default`) for linking the C++ runtime. 737 738 ### Configure Control Variables 739 740 It is possible to control certain aspects of `configure` by overriding the 741 value of `configure` variables, either on the command line or in the 742 environment. 743 744 Normally, this is **not recommended**. If used improperly, it can lead to a 745 broken configuration. Unless you're well versed in the build system, this is 746 hard to use properly. Therefore, `configure` will print a warning if this is 747 detected. 748 749 However, there are a few `configure` variables, known as *control variables* 750 that are supposed to be overriden on the command line. These are variables that 751 describe the location of tools needed by the build, like `MAKE` or `GREP`. If 752 any such variable is specified, `configure` will use that value instead of 753 trying to autodetect the tool. For instance, `bash configure 754 MAKE=/opt/gnumake4.0/bin/make`. 755 756 If a configure argument exists, use that instead, e.g. use `--with-jtreg` 757 instead of setting `JTREGEXE`. 758 759 Also note that, despite what autoconf claims, setting `CFLAGS` will not 760 accomplish anything. Instead use `--with-extra-cflags` (and similar for 761 `cxxflags` and `ldflags`). 762 763 ## Running Make 764 765 When you have a proper configuration, all you need to do to build OpenJDK is to 766 run `make`. (But see the warning at [GNU Make](#gnu-make) about running the 767 correct version of make.) 768 769 When running `make` without any arguments, the default target is used, which is 770 the same as running `make default` or `make jdk`. This will build a minimal (or 771 roughly minimal) set of compiled output (known as an "exploded image") needed 772 for a developer to actually execute the newly built JDK. The idea is that in an 773 incremental development fashion, when doing a normal make, you should only 774 spend time recompiling what's changed (making it purely incremental) and only 775 do the work that's needed to actually run and test your code. 776 777 The output of the exploded image resides in `$BUILD/jdk`. You can test the 778 newly built JDK like this: `$BUILD/jdk/bin/java -version`. 779 780 ### Common Make Targets 781 782 Apart from the default target, here are some common make targets: 783 784 * `hotspot` - Build all of hotspot (but only hotspot) 785 * `hotspot-<variant>` - Build just the specified jvm variant 786 * `images` or `product-images` - Build the JRE and JDK images 787 * `docs` or `docs-image` - Build the documentation image 788 * `test-image` - Build the test image 789 * `all` or `all-images` - Build all images (product, docs and test) 790 * `bootcycle-images` - Build images twice, second time with newly built JDK 791 (good for testing) 792 * `clean` - Remove all files generated by make, but not those generated by 793 configure 794 * `dist-clean` - Remove all files, including configuration 795 796 Run `make help` to get an up-to-date list of important make targets and make 797 control variables. 798 799 It is possible to build just a single module, a single phase, or a single phase 800 of a single module, by creating make targets according to these followin 801 patterns. A phase can be either of `gensrc`, `gendata`, `copy`, `java`, 802 `launchers`, `libs` or `rmic`. See [Using Fine-Grained Make Targets]( 803 #using-fine-grained-make-targets) for more details about this functionality. 804 805 * `<phase>` - Build the specified phase and everything it depends on 806 * `<module>` - Build the specified module and everything it depends on 807 * `<module>-<phase>` - Compile the specified phase for the specified module 808 and everything it depends on 809 810 Similarly, it is possible to clean just a part of the build by creating make 811 targets according to these patterns: 812 813 * `clean-<outputdir>` - Remove the subdir in the output dir with the name 814 * `clean-<phase>` - Remove all build results related to a certain build 815 phase 816 * `clean-<module>` - Remove all build results related to a certain module 817 * `clean-<module>-<phase>` - Remove all build results related to a certain 818 module and phase 819 820 ### Make Control Variables 821 822 It is possible to control `make` behavior by overriding the value of `make` 823 variables, either on the command line or in the environment. 824 825 Normally, this is **not recommended**. If used improperly, it can lead to a 826 broken build. Unless you're well versed in the build system, this is hard to 827 use properly. Therefore, `make` will print a warning if this is detected. 828 829 However, there are a few `make` variables, known as *control variables* that 830 are supposed to be overriden on the command line. These make up the "make time" 831 configuration, as opposed to the "configure time" configuration. 832 833 #### General Make Control Variables 834 835 * `JOBS` - Specify the number of jobs to build with. See [Build 836 Performance](#build-performance). 837 * `LOG` - Specify the logging level and functionality. See [Checking the 838 Build Log File](#checking-the-build-log-file) 839 * `CONF` and `CONF_NAME` - Selecting the configuration(s) to use. See [Using 840 Multiple Configurations](#using-multiple-configurations) 841 842 #### Test Make Control Variables 843 844 These make control variables only make sense when running tests. Please see 845 [Testing OpenJDK](testing.html) for details. 846 847 * `TEST` 848 * `TEST_JOBS` 849 * `JTREG` 850 * `GTEST` 851 852 #### Advanced Make Control Variables 853 854 These advanced make control variables can be potentially unsafe. See [Hints and 855 Suggestions for Advanced Users](#hints-and-suggestions-for-advanced-users) and 856 [Understanding the Build System](#understanding-the-build-system) for details. 857 858 * `SPEC` 859 * `CONF_CHECK` 860 * `COMPARE_BUILD` 861 * `JDK_FILTER` 862 863 ## Running Tests 864 865 Most of the OpenJDK tests are using the [JTReg](http://openjdk.java.net/jtreg) 866 test framework. Make sure that your configuration knows where to find your 867 installation of JTReg. If this is not picked up automatically, use the 868 `--with-jtreg=<path to jtreg home>` option to point to the JTReg framework. 869 Note that this option should point to the JTReg home, i.e. the top directory, 870 containing `lib/jtreg.jar` etc. 871 872 To execute the most basic tests (tier 1), use: 873 ``` 874 make run-test-tier1 875 ``` 876 877 For more details on how to run tests, please see the [Testing 878 OpenJDK](testing.html) document. 879 880 ## Cross-compiling 881 882 Cross-compiling means using one platform (the *build* platform) to generate 883 output that can ran on another platform (the *target* platform). 884 885 The typical reason for cross-compiling is that the build is performed on a more 886 powerful desktop computer, but the resulting binaries will be able to run on a 887 different, typically low-performing system. Most of the complications that 888 arise when building for embedded is due to this separation of *build* and 889 *target* systems. 890 891 This requires a more complex setup and build procedure. This section assumes 892 you are familiar with cross-compiling in general, and will only deal with the 893 particularities of cross-compiling OpenJDK. If you are new to cross-compiling, 894 please see the [external links at Wikipedia]( 895 https://en.wikipedia.org/wiki/Cross_compiler#External_links) for a good start 896 on reading materials. 897 898 Cross-compiling OpenJDK requires you to be able to build both for the build 899 platform and for the target platform. The reason for the former is that we need 900 to build and execute tools during the build process, both native tools and Java 901 tools. 902 903 If all you want to do is to compile a 32-bit version, for the same OS, on a 904 64-bit machine, consider using `--with-target-bits=32` instead of doing a 905 full-blown cross-compilation. (While this surely is possible, it's a lot more 906 work and will take much longer to build.) 907 908 ### Boot JDK and Build JDK 909 910 When cross-compiling, make sure you use a boot JDK that runs on the *build* 911 system, and not on the *target* system. 912 913 To be able to build, we need a "Build JDK", which is a JDK built from the 914 current sources (that is, the same as the end result of the entire build 915 process), but able to run on the *build* system, and not the *target* system. 916 (In contrast, the Boot JDK should be from an older release, e.g. JDK 8 when 917 building JDK 9.) 918 919 The build process will create a minimal Build JDK for you, as part of building. 920 To speed up the build, you can use `--with-build-jdk` to `configure` to point 921 to a pre-built Build JDK. Please note that the build result is unpredictable, 922 and can possibly break in subtle ways, if the Build JDK does not **exactly** 923 match the current sources. 924 925 ### Specifying the Target Platform 926 927 You *must* specify the target platform when cross-compiling. Doing so will also 928 automatically turn the build into a cross-compiling mode. The simplest way to 929 do this is to use the `--openjdk-target` argument, e.g. 930 `--openjdk-target=arm-linux-gnueabihf`. or `--openjdk-target=aarch64-oe-linux`. 931 This will automatically set the `--build`, `--host` and `--target` options for 932 autoconf, which can otherwise be confusing. (In autoconf terminology, the 933 "target" is known as "host", and "target" is used for building a Canadian 934 cross-compiler.) 935 936 ### Toolchain Considerations 937 938 You will need two copies of your toolchain, one which generates output that can 939 run on the target system (the normal, or *target*, toolchain), and one that 940 generates output that can run on the build system (the *build* toolchain). Note 941 that cross-compiling is only supported for gcc at the time being. The gcc 942 standard is to prefix cross-compiling toolchains with the target denominator. 943 If you follow this standard, `configure` is likely to pick up the toolchain 944 correctly. 945 946 The *build* toolchain will be autodetected just the same way the normal 947 *build*/*target* toolchain will be autodetected when not cross-compiling. If 948 this is not what you want, or if the autodetection fails, you can specify a 949 devkit containing the *build* toolchain using `--with-build-devkit` to 950 `configure`, or by giving `BUILD_CC` and `BUILD_CXX` arguments. 951 952 It is often helpful to locate the cross-compilation tools, headers and 953 libraries in a separate directory, outside the normal path, and point out that 954 directory to `configure`. Do this by setting the sysroot (`--with-sysroot`) and 955 appending the directory when searching for cross-compilations tools 956 (`--with-toolchain-path`). As a compact form, you can also use `--with-devkit` 957 to point to a single directory, if it is correctly setup. (See `basics.m4` for 958 details.) 959 960 If you are unsure what toolchain and versions to use, these have been proved 961 working at the time of writing: 962 963 * [aarch64]( 964 https://releases.linaro.org/archive/13.11/components/toolchain/binaries/gcc-linaro-aarch64-linux-gnu-4.8-2013.11_linux.tar.xz) 965 * [arm 32-bit hardware floating point]( 966 https://launchpad.net/linaro-toolchain-unsupported/trunk/2012.09/+download/gcc-linaro-arm-linux-gnueabihf-raspbian-2012.09-20120921_linux.tar.bz2) 967 968 ### Native Libraries 969 970 You will need copies of external native libraries for the *target* system, 971 present on the *build* machine while building. 972 973 Take care not to replace the *build* system's version of these libraries by 974 mistake, since that can render the *build* machine unusable. 975 976 Make sure that the libraries you point to (ALSA, X11, etc) are for the 977 *target*, not the *build*, platform. 978 979 #### ALSA 980 981 You will need alsa libraries suitable for your *target* system. For most cases, 982 using Debian's pre-built libraries work fine. 983 984 Note that alsa is needed even if you only want to build a headless JDK. 985 986 * Go to [Debian Package Search](https://www.debian.org/distrib/packages) and 987 search for the `libasound2` and `libasound2-dev` packages for your *target* 988 system. Download them to /tmp. 989 990 * Install the libraries into the cross-compilation toolchain. For instance: 991 ``` 992 cd /tools/gcc-linaro-arm-linux-gnueabihf-raspbian-2012.09-20120921_linux/arm-linux-gnueabihf/libc 993 dpkg-deb -x /tmp/libasound2_1.0.25-4_armhf.deb . 994 dpkg-deb -x /tmp/libasound2-dev_1.0.25-4_armhf.deb . 995 ``` 996 997 * If alsa is not properly detected by `configure`, you can point it out by 998 `--with-alsa`. 999 1000 #### X11 1001 1002 You will need X11 libraries suitable for your *target* system. For most cases, 1003 using Debian's pre-built libraries work fine. 1004 1005 Note that X11 is needed even if you only want to build a headless JDK. 1006 1007 * Go to [Debian Package Search](https://www.debian.org/distrib/packages), 1008 search for the following packages for your *target* system, and download them 1009 to /tmp/target-x11: 1010 * libxi 1011 * libxi-dev 1012 * x11proto-core-dev 1013 * x11proto-input-dev 1014 * x11proto-kb-dev 1015 * x11proto-render-dev 1016 * x11proto-xext-dev 1017 * libice-dev 1018 * libxrender 1019 * libxrender-dev 1020 * libsm-dev 1021 * libxt-dev 1022 * libx11 1023 * libx11-dev 1024 * libxtst 1025 * libxtst-dev 1026 * libxext 1027 * libxext-dev 1028 1029 * Install the libraries into the cross-compilation toolchain. For instance: 1030 ``` 1031 cd /tools/gcc-linaro-arm-linux-gnueabihf-raspbian-2012.09-20120921_linux/arm-linux-gnueabihf/libc/usr 1032 mkdir X11R6 1033 cd X11R6 1034 for deb in /tmp/target-x11/*.deb ; do dpkg-deb -x $deb . ; done 1035 mv usr/* . 1036 cd lib 1037 cp arm-linux-gnueabihf/* . 1038 ``` 1039 1040 You can ignore the following messages. These libraries are not needed to 1041 successfully complete a full JDK build. 1042 ``` 1043 cp: cannot stat `arm-linux-gnueabihf/libICE.so': No such file or directory 1044 cp: cannot stat `arm-linux-gnueabihf/libSM.so': No such file or directory 1045 cp: cannot stat `arm-linux-gnueabihf/libXt.so': No such file or directory 1046 ``` 1047 1048 * If the X11 libraries are not properly detected by `configure`, you can 1049 point them out by `--with-x`. 1050 1051 ### Building for ARM/aarch64 1052 1053 A common cross-compilation target is the ARM CPU. When building for ARM, it is 1054 useful to set the ABI profile. A number of pre-defined ABI profiles are 1055 available using `--with-abi-profile`: arm-vfp-sflt, arm-vfp-hflt, arm-sflt, 1056 armv5-vfp-sflt, armv6-vfp-hflt. Note that soft-float ABIs are no longer 1057 properly supported on OpenJDK. 1058 1059 OpenJDK contains two different ports for the aarch64 platform, one is the 1060 original aarch64 port from the [AArch64 Port Project]( 1061 http://openjdk.java.net/projects/aarch64-port) and one is a 64-bit version of 1062 the Oracle contributed ARM port. When targeting aarch64, by the default the 1063 original aarch64 port is used. To select the Oracle ARM 64 port, use 1064 `--with-cpu-port=arm64`. Also set the corresponding value (`aarch64` or 1065 `arm64`) to --with-abi-profile, to ensure a consistent build. 1066 1067 ### Verifying the Build 1068 1069 The build will end up in a directory named like 1070 `build/linux-arm-normal-server-release`. 1071 1072 Inside this build output directory, the `images/jdk` and `images/jre` will 1073 contain the newly built JDK and JRE, respectively, for your *target* system. 1074 1075 Copy these folders to your *target* system. Then you can run e.g. 1076 `images/jdk/bin/java -version`. 1077 1078 ## Build Performance 1079 1080 Building OpenJDK requires a lot of horsepower. Some of the build tools can be 1081 adjusted to utilize more or less of resources such as parallel threads and 1082 memory. The `configure` script analyzes your system and selects reasonable 1083 values for such options based on your hardware. If you encounter resource 1084 problems, such as out of memory conditions, you can modify the detected values 1085 with: 1086 1087 * `--with-num-cores` -- number of cores in the build system, e.g. 1088 `--with-num-cores=8`. 1089 1090 * `--with-memory-size` -- memory (in MB) available in the build system, e.g. 1091 `--with-memory-size=1024` 1092 1093 You can also specify directly the number of build jobs to use with 1094 `--with-jobs=N` to `configure`, or `JOBS=N` to `make`. Do not use the `-j` flag 1095 to `make`. In most cases it will be ignored by the makefiles, but it can cause 1096 problems for some make targets. 1097 1098 It might also be necessary to specify the JVM arguments passed to the Boot JDK, 1099 using e.g. `--with-boot-jdk-jvmargs="-Xmx8G"`. Doing so will override the 1100 default JVM arguments passed to the Boot JDK. 1101 1102 At the end of a successful execution of `configure`, you will get a performance 1103 summary, indicating how well the build will perform. Here you will also get 1104 performance hints. If you want to build fast, pay attention to those! 1105 1106 If you want to tweak build performance, run with `make LOG=info` to get a build 1107 time summary at the end of the build process. 1108 1109 ### Disk Speed 1110 1111 If you are using network shares, e.g. via NFS, for your source code, make sure 1112 the build directory is situated on local disk (e.g. by `ln -s 1113 /localdisk/jdk-build $JDK-SHARE/build`). The performance penalty is extremely 1114 high for building on a network share; close to unusable. 1115 1116 Also, make sure that your build tools (including Boot JDK and toolchain) is 1117 located on a local disk and not a network share. 1118 1119 As has been stressed elsewhere, do use SSD for source code and build directory, 1120 as well as (if possible) the build tools. 1121 1122 ### Virus Checking 1123 1124 The use of virus checking software, especially on Windows, can *significantly* 1125 slow down building of OpenJDK. If possible, turn off such software, or exclude 1126 the directory containing the OpenJDK source code from on-the-fly checking. 1127 1128 ### Ccache 1129 1130 The OpenJDK build supports building with ccache when using gcc or clang. Using 1131 ccache can radically speed up compilation of native code if you often rebuild 1132 the same sources. Your milage may vary however, so we recommend evaluating it 1133 for yourself. To enable it, make sure it's on the path and configure with 1134 `--enable-ccache`. 1135 1136 ### Precompiled Headers 1137 1138 By default, the Hotspot build uses preccompiled headers (PCH) on the toolchains 1139 were it is properly supported (clang, gcc, and Visual Studio). Normally, this 1140 speeds up the build process, but in some circumstances, it can actually slow 1141 things down. 1142 1143 You can experiment by disabling precompiled headers using 1144 `--disable-precompiled-headers`. 1145 1146 ### Icecc / icecream 1147 1148 [icecc/icecream](http://github.com/icecc/icecream) is a simple way to setup a 1149 distributed compiler network. If you have multiple machines available for 1150 building OpenJDK, you can drastically cut individual build times by utilizing 1151 it. 1152 1153 To use, setup an icecc network, and install icecc on the build machine. Then 1154 run `configure` using `--enable-icecc`. 1155 1156 ### Using sjavac 1157 1158 To speed up Java compilation, especially incremental compilations, you can try 1159 the experimental sjavac compiler by using `--enable-sjavac`. 1160 1161 ### Building the Right Target 1162 1163 Selecting the proper target to build can have dramatic impact on build time. 1164 For normal usage, `jdk` or the default target is just fine. You only need to 1165 build `images` for shipping, or if your tests require it. 1166 1167 See also [Using Fine-Grained Make Targets](#using-fine-grained-make-targets) on 1168 how to build an even smaller subset of the product. 1169 1170 ## Troubleshooting 1171 1172 If your build fails, it can sometimes be difficult to pinpoint the problem or 1173 find a proper solution. 1174 1175 ### Locating the Source of the Error 1176 1177 When a build fails, it can be hard to pinpoint the actual cause of the error. 1178 In a typical build process, different parts of the product build in parallel, 1179 with the output interlaced. 1180 1181 #### Build Failure Summary 1182 1183 To help you, the build system will print a failure summary at the end. It looks 1184 like this: 1185 1186 ``` 1187 ERROR: Build failed for target 'hotspot' in configuration 'linux-x64' (exit code 2) 1188 1189 === Output from failing command(s) repeated here === 1190 * For target hotspot_variant-server_libjvm_objs_psMemoryPool.o: 1191 /localhome/hg/jdk9-sandbox/hotspot/src/share/vm/services/psMemoryPool.cpp:1:1: error: 'failhere' does not name a type 1192 ... (rest of output omitted) 1193 1194 * All command lines available in /localhome/hg/jdk9-sandbox/build/linux-x64/make-support/failure-logs. 1195 === End of repeated output === 1196 1197 === Make failed targets repeated here === 1198 lib/CompileJvm.gmk:207: recipe for target '/localhome/hg/jdk9-sandbox/build/linux-x64/hotspot/variant-server/libjvm/objs/psMemoryPool.o' failed 1199 make/Main.gmk:263: recipe for target 'hotspot-server-libs' failed 1200 === End of repeated output === 1201 1202 Hint: Try searching the build log for the name of the first failed target. 1203 Hint: If caused by a warning, try configure --disable-warnings-as-errors. 1204 ``` 1205 1206 Let's break it down! First, the selected configuration, and the top-level 1207 target you entered on the command line that caused the failure is printed. 1208 1209 Then, between the `Output from failing command(s) repeated here` and `End of 1210 repeated output` the first lines of output (stdout and stderr) from the actual 1211 failing command is repeated. In most cases, this is the error message that 1212 caused the build to fail. If multiple commands were failing (this can happen in 1213 a parallel build), output from all failed commands will be printed here. 1214 1215 The path to the `failure-logs` directory is printed. In this file you will find 1216 a `<target>.log` file that contains the output from this command in its 1217 entirety, and also a `<target>.cmd`, which contain the complete command line 1218 used for running this command. You can re-run the failing command by executing 1219 `. <path to failure-logs>/<target>.cmd` in your shell. 1220 1221 Another way to trace the failure is to follow the chain of make targets, from 1222 top-level targets to individual file targets. Between `Make failed targets 1223 repeated here` and `End of repeated output` the output from make showing this 1224 chain is repeated. The first failed recipe will typically contain the full path 1225 to the file in question that failed to compile. Following lines will show a 1226 trace of make targets why we ended up trying to compile that file. 1227 1228 Finally, some hints are given on how to locate the error in the complete log. 1229 In this example, we would try searching the log file for "`psMemoryPool.o`". 1230 Another way to quickly locate make errors in the log is to search for "`] 1231 Error`" or "`***`". 1232 1233 Note that the build failure summary will only help you if the issue was a 1234 compilation failure or similar. If the problem is more esoteric, or is due to 1235 errors in the build machinery, you will likely get empty output logs, and `No 1236 indication of failed target found` instead of the make target chain. 1237 1238 #### Checking the Build Log File 1239 1240 The output (stdout and stderr) from the latest build is always stored in 1241 `$BUILD/build.log`. The previous build log is stored as `build.log.old`. This 1242 means that it is not necessary to redirect the build output yourself if you 1243 want to process it. 1244 1245 You can increase the verbosity of the log file, by the `LOG` control variable 1246 to `make`. If you want to see the command lines used in compilations, use 1247 `LOG=cmdlines`. To increase the general verbosity, use `LOG=info`, `LOG=debug` 1248 or `LOG=trace`. Both of these can be combined with `cmdlines`, e.g. 1249 `LOG=info,cmdlines`. The `debug` log level will show most shell commands 1250 executed by make, and `trace` will show all. Beware that both these log levels 1251 will produce a massive build log! 1252 1253 ### Fixing Unexpected Build Failures 1254 1255 Most of the time, the build will fail due to incorrect changes in the source 1256 code. 1257 1258 Sometimes the build can fail with no apparent changes that have caused the 1259 failure. If this is the first time you are building OpenJDK on this particular 1260 computer, and the build fails, the problem is likely with your build 1261 environment. But even if you have previously built OpenJDK with success, and it 1262 now fails, your build environment might have changed (perhaps due to OS 1263 upgrades or similar). But most likely, such failures are due to problems with 1264 the incremental rebuild. 1265 1266 #### Problems with the Build Environment 1267 1268 Make sure your configuration is correct. Re-run `configure`, and look for any 1269 warnings. Warnings that appear in the middle of the `configure` output is also 1270 repeated at the end, after the summary. The entire log is stored in 1271 `$BUILD/configure.log`. 1272 1273 Verify that the summary at the end looks correct. Are you indeed using the Boot 1274 JDK and native toolchain that you expect? 1275 1276 By default, OpenJDK has a strict approach where warnings from the compiler is 1277 considered errors which fail the build. For very new or very old compiler 1278 versions, this can trigger new classes of warnings, which thus fails the build. 1279 Run `configure` with `--disable-warnings-as-errors` to turn of this behavior. 1280 (The warnings will still show, but not make the build fail.) 1281 1282 #### Problems with Incremental Rebuilds 1283 1284 Incremental rebuilds mean that when you modify part of the product, only the 1285 affected parts get rebuilt. While this works great in most cases, and 1286 significantly speed up the development process, from time to time complex 1287 interdependencies will result in an incorrect build result. This is the most 1288 common cause for unexpected build problems, together with inconsistencies 1289 between the different Mercurial repositories in the forest. 1290 1291 Here are a suggested list of things to try if you are having unexpected build 1292 problems. Each step requires more time than the one before, so try them in 1293 order. Most issues will be solved at step 1 or 2. 1294 1295 1. Make sure your forest is up-to-date 1296 1297 Run `bash get_source.sh` to make sure you have the latest version of all 1298 repositories. 1299 1300 2. Clean build results 1301 1302 The simplest way to fix incremental rebuild issues is to run `make clean`. 1303 This will remove all build results, but not the configuration or any build 1304 system support artifacts. In most cases, this will solve build errors 1305 resulting from incremental build mismatches. 1306 1307 3. Completely clean the build directory. 1308 1309 If this does not work, the next step is to run `make dist-clean`, or 1310 removing the build output directory (`$BUILD`). This will clean all 1311 generated output, including your configuration. You will need to re-run 1312 `configure` after this step. A good idea is to run `make 1313 print-configuration` before running `make dist-clean`, as this will print 1314 your current `configure` command line. Here's a way to do this: 1315 1316 ``` 1317 make print-configuration > current-configuration 1318 make dist-clean 1319 bash configure $(cat current-configuration) 1320 make 1321 ``` 1322 1323 4. Re-clone the Mercurial forest 1324 1325 Sometimes the Mercurial repositories themselves gets in a state that causes 1326 the product to be un-buildable. In such a case, the simplest solution is 1327 often the "sledgehammer approach": delete the entire forest, and re-clone 1328 it. If you have local changes, save them first to a different location 1329 using `hg export`. 1330 1331 ### Specific Build Issues 1332 1333 #### Clock Skew 1334 1335 If you get an error message like this: 1336 ``` 1337 File 'xxx' has modification time in the future. 1338 Clock skew detected. Your build may be incomplete. 1339 ``` 1340 then the clock on your build machine is out of sync with the timestamps on the 1341 source files. Other errors, apparently unrelated but in fact caused by the 1342 clock skew, can occur along with the clock skew warnings. These secondary 1343 errors may tend to obscure the fact that the true root cause of the problem is 1344 an out-of-sync clock. 1345 1346 If you see these warnings, reset the clock on the build machine, run `make 1347 clean` and restart the build. 1348 1349 #### Out of Memory Errors 1350 1351 On Solaris, you might get an error message like this: 1352 ``` 1353 Trouble writing out table to disk 1354 ``` 1355 To solve this, increase the amount of swap space on your build machine. 1356 1357 On Windows, you might get error messages like this: 1358 ``` 1359 fatal error - couldn't allocate heap 1360 cannot create ... Permission denied 1361 spawn failed 1362 ``` 1363 This can be a sign of a Cygwin problem. See the information about solving 1364 problems in the [Cygwin](#cygwin) section. Rebooting the computer might help 1365 temporarily. 1366 1367 ### Getting Help 1368 1369 If none of the suggestions in this document helps you, or if you find what you 1370 believe is a bug in the build system, please contact the Build Group by sending 1371 a mail to [build-dev@openjdk.java.net](mailto:build-dev@openjdk.java.net). 1372 Please include the relevant parts of the configure and/or build log. 1373 1374 If you need general help or advice about developing for OpenJDK, you can also 1375 contact the Adoption Group. See the section on [Contributing to OpenJDK]( 1376 #contributing-to-openjdk) for more information. 1377 1378 ## Hints and Suggestions for Advanced Users 1379 1380 ### Setting Up a Forest for Pushing Changes (defpath) 1381 1382 To help you prepare a proper push path for a Mercurial repository, there exists 1383 a useful tool known as [defpath]( 1384 http://openjdk.java.net/projects/code-tools/defpath). It will help you setup a 1385 proper push path for pushing changes to OpenJDK. 1386 1387 Install the extension by cloning 1388 `http://hg.openjdk.java.net/code-tools/defpath` and updating your `.hgrc` file. 1389 Here's one way to do this: 1390 1391 ``` 1392 cd ~ 1393 mkdir hg-ext 1394 cd hg-ext 1395 hg clone http://hg.openjdk.java.net/code-tools/defpath 1396 cat << EOT >> ~/.hgrc 1397 [extensions] 1398 defpath=~/hg-ext/defpath/defpath.py 1399 EOT 1400 ``` 1401 1402 You can now setup a proper push path using: 1403 ``` 1404 hg defpath -d -u <your OpenJDK username> 1405 ``` 1406 1407 If you also have the `trees` extension installed in Mercurial, you will 1408 automatically get a `tdefpath` command, which is even more useful. By running 1409 `hg tdefpath -du <username>` in the top repository of your forest, all repos 1410 will get setup automatically. This is the recommended usage. 1411 1412 ### Bash Completion 1413 1414 The `configure` and `make` commands tries to play nice with bash command-line 1415 completion (using `<tab>` or `<tab><tab>`). To use this functionality, make 1416 sure you enable completion in your `~/.bashrc` (see instructions for bash in 1417 your operating system). 1418 1419 Make completion will work out of the box, and will complete valid make targets. 1420 For instance, typing `make jdk-i<tab>` will complete to `make jdk-image`. 1421 1422 The `configure` script can get completion for options, but for this to work you 1423 need to help `bash` on the way. The standard way of running the script, `bash 1424 configure`, will not be understood by bash completion. You need `configure` to 1425 be the command to run. One way to achieve this is to add a simple helper script 1426 to your path: 1427 1428 ``` 1429 cat << EOT > /tmp/configure 1430 #!/bin/bash 1431 if [ \$(pwd) = \$(cd \$(dirname \$0); pwd) ] ; then 1432 echo >&2 "Abort: Trying to call configure helper recursively" 1433 exit 1 1434 fi 1435 1436 bash \$PWD/configure "\$@" 1437 EOT 1438 chmod +x /tmp/configure 1439 sudo mv /tmp/configure /usr/local/bin 1440 ``` 1441 1442 Now `configure --en<tab>-dt<tab>` will result in `configure --enable-dtrace`. 1443 1444 ### Using Multiple Configurations 1445 1446 You can have multiple configurations for a single source forest. When you 1447 create a new configuration, run `configure --with-conf-name=<name>` to create a 1448 configuration with the name `<name>`. Alternatively, you can create a directory 1449 under `build` and run `configure` from there, e.g. `mkdir build/<name> && cd 1450 build/<name> && bash ../../configure`. 1451 1452 Then you can build that configuration using `make CONF_NAME=<name>` or `make 1453 CONF=<pattern>`, where `<pattern>` is a substring matching one or several 1454 configurations, e.g. `CONF=debug`. The special empty pattern (`CONF=`) will 1455 match *all* available configuration, so `make CONF= hotspot` will build the 1456 `hotspot` target for all configurations. Alternatively, you can execute `make` 1457 in the configuration directory, e.g. `cd build/<name> && make`. 1458 1459 ### Handling Reconfigurations 1460 1461 If you update the forest and part of the configure script has changed, the 1462 build system will force you to re-run `configure`. 1463 1464 Most of the time, you will be fine by running `configure` again with the same 1465 arguments as the last time, which can easily be performed by `make 1466 reconfigure`. To simplify this, you can use the `CONF_CHECK` make control 1467 variable, either as `make CONF_CHECK=auto`, or by setting an environment 1468 variable. For instance, if you add `export CONF_CHECK=auto` to your `.bashrc` 1469 file, `make` will always run `reconfigure` automatically whenever the configure 1470 script has changed. 1471 1472 You can also use `CONF_CHECK=ignore` to skip the check for a needed configure 1473 update. This might speed up the build, but comes at the risk of an incorrect 1474 build result. This is only recommended if you know what you're doing. 1475 1476 From time to time, you will also need to modify the command line to `configure` 1477 due to changes. Use `make print-configure` to show the command line used for 1478 your current configuration. 1479 1480 ### Using Fine-Grained Make Targets 1481 1482 The default behavior for make is to create consistent and correct output, at 1483 the expense of build speed, if necessary. 1484 1485 If you are prepared to take some risk of an incorrect build, and know enough of 1486 the system to understand how things build and interact, you can speed up the 1487 build process considerably by instructing make to only build a portion of the 1488 product. 1489 1490 #### Building Individual Modules 1491 1492 The safe way to use fine-grained make targets is to use the module specific 1493 make targets. All source code in JDK 9 is organized so it belongs to a module, 1494 e.g. `java.base` or `jdk.jdwp.agent`. You can build only a specific module, by 1495 giving it as make target: `make jdk.jdwp.agent`. If the specified module 1496 depends on other modules (e.g. `java.base`), those modules will be built first. 1497 1498 You can also specify a set of modules, just as you can always specify a set of 1499 make targets: `make jdk.crypto.cryptoki jdk.crypto.ec jdk.crypto.mscapi 1500 jdk.crypto.ucrypto` 1501 1502 #### Building Individual Module Phases 1503 1504 The build process for each module is divided into separate phases. Not all 1505 modules need all phases. Which are needed depends on what kind of source code 1506 and other artifact the module consists of. The phases are: 1507 1508 * `gensrc` (Generate source code to compile) 1509 * `gendata` (Generate non-source code artifacts) 1510 * `copy` (Copy resource artifacts) 1511 * `java` (Compile Java code) 1512 * `launchers` (Compile native executables) 1513 * `libs` (Compile native libraries) 1514 * `rmic` (Run the `rmic` tool) 1515 1516 You can build only a single phase for a module by using the notation 1517 `$MODULE-$PHASE`. For instance, to build the `gensrc` phase for `java.base`, 1518 use `make java.base-gensrc`. 1519 1520 Note that some phases may depend on others, e.g. `java` depends on `gensrc` (if 1521 present). Make will build all needed prerequisites before building the 1522 requested phase. 1523 1524 #### Skipping the Dependency Check 1525 1526 When using an iterative development style with frequent quick rebuilds, the 1527 dependency check made by make can take up a significant portion of the time 1528 spent on the rebuild. In such cases, it can be useful to bypass the dependency 1529 check in make. 1530 1531 > **Note that if used incorrectly, this can lead to a broken build!** 1532 1533 To achieve this, append `-only` to the build target. For instance, `make 1534 jdk.jdwp.agent-java-only` will *only* build the `java` phase of the 1535 `jdk.jdwp.agent` module. If the required dependencies are not present, the 1536 build can fail. On the other hand, the execution time measures in milliseconds. 1537 1538 A useful pattern is to build the first time normally (e.g. `make 1539 jdk.jdwp.agent`) and then on subsequent builds, use the `-only` make target. 1540 1541 #### Rebuilding Part of java.base (JDK\_FILTER) 1542 1543 If you are modifying files in `java.base`, which is the by far largest module 1544 in OpenJDK, then you need to rebuild all those files whenever a single file has 1545 changed. (This inefficiency will hopefully be addressed in JDK 10.) 1546 1547 As a hack, you can use the make control variable `JDK_FILTER` to specify a 1548 pattern that will be used to limit the set of files being recompiled. For 1549 instance, `make java.base JDK_FILTER=javax/crypto` (or, to combine methods, 1550 `make java.base-java-only JDK_FILTER=javax/crypto`) will limit the compilation 1551 to files in the `javax.crypto` package. 1552 1553 ### Learn About Mercurial 1554 1555 To become an efficient OpenJDK developer, it is recommended that you invest in 1556 learning Mercurial properly. Here are some links that can get you started: 1557 1558 * [Mercurial for git users](http://www.mercurial-scm.org/wiki/GitConcepts) 1559 * [The official Mercurial tutorial](http://www.mercurial-scm.org/wiki/Tutorial) 1560 * [hg init](http://hginit.com/) 1561 * [Mercurial: The Definitive Guide](http://hgbook.red-bean.com/read/) 1562 1563 ## Understanding the Build System 1564 1565 This section will give you a more technical description on the details of the 1566 build system. 1567 1568 ### Configurations 1569 1570 The build system expects to find one or more configuration. These are 1571 technically defined by the `spec.gmk` in a subdirectory to the `build` 1572 subdirectory. The `spec.gmk` file is generated by `configure`, and contains in 1573 principle the configuration (directly or by files included by `spec.gmk`). 1574 1575 You can, in fact, select a configuration to build by pointing to the `spec.gmk` 1576 file with the `SPEC` make control variable, e.g. `make SPEC=$BUILD/spec.gmk`. 1577 While this is not the recommended way to call `make` as a user, it is what is 1578 used under the hood by the build system. 1579 1580 ### Build Output Structure 1581 1582 The build output for a configuration will end up in `build/<configuration 1583 name>`, which we refer to as `$BUILD` in this document. The `$BUILD` directory 1584 contains the following important directories: 1585 1586 ``` 1587 buildtools/ 1588 configure-support/ 1589 hotspot/ 1590 images/ 1591 jdk/ 1592 make-support/ 1593 support/ 1594 test-results/ 1595 test-support/ 1596 ``` 1597 1598 This is what they are used for: 1599 1600 * `images`: This is the directory were the output of the `*-image` make 1601 targets end up. For instance, `make jdk-image` ends up in `images/jdk`. 1602 1603 * `jdk`: This is the "exploded image". After `make jdk`, you will be able to 1604 launch the newly built JDK by running `$BUILD/jdk/bin/java`. 1605 1606 * `test-results`: This directory contains the results from running tests. 1607 1608 * `support`: This is an area for intermediate files needed during the build, 1609 e.g. generated source code, object files and class files. Some noteworthy 1610 directories in `support` is `gensrc`, which contains the generated source 1611 code, and the `modules_*` directories, which contains the files in a 1612 per-module hierarchy that will later be collapsed into the `jdk` directory 1613 of the exploded image. 1614 1615 * `buildtools`: This is an area for tools compiled for the build platform 1616 that are used during the rest of the build. 1617 1618 * `hotspot`: This is an area for intermediate files needed when building 1619 hotspot. 1620 1621 * `configure-support`, `make-support` and `test-support`: These directories 1622 contain files that are needed by the build system for `configure`, `make` 1623 and for running tests. 1624 1625 ### Fixpath 1626 1627 Windows path typically look like `C:\User\foo`, while Unix paths look like 1628 `/home/foo`. Tools with roots from Unix often experience issues related to this 1629 mismatch when running on Windows. 1630 1631 In the OpenJDK build, we always use Unix paths internally, and only just before 1632 calling a tool that does not understand Unix paths do we convert them to 1633 Windows paths. 1634 1635 This conversion is done by the `fixpath` tool, which is a small wrapper that 1636 modifies unix-style paths to Windows-style paths in command lines. Fixpath is 1637 compiled automatically by `configure`. 1638 1639 ### Native Debug Symbols 1640 1641 Native libraries and executables can have debug symbol (and other debug 1642 information) associated with them. How this works is very much platform 1643 dependent, but a common problem is that debug symbol information takes a lot of 1644 disk space, but is rarely needed by the end user. 1645 1646 The OpenJDK supports different methods on how to handle debug symbols. The 1647 method used is selected by `--with-native-debug-symbols`, and available methods 1648 are `none`, `internal`, `external`, `zipped`. 1649 1650 * `none` means that no debug symbols will be generated during the build. 1651 1652 * `internal` means that debug symbols will be generated during the build, and 1653 they will be stored in the generated binary. 1654 1655 * `external` means that debug symbols will be generated during the build, and 1656 after the compilation, they will be moved into a separate `.debuginfo` file. 1657 (This was previously known as FDS, Full Debug Symbols). 1658 1659 * `zipped` is like `external`, but the .debuginfo file will also be zipped 1660 into a `.diz` file. 1661 1662 When building for distribution, `zipped` is a good solution. Binaries built 1663 with `internal` is suitable for use by developers, since they facilitate 1664 debugging, but should be stripped before distributed to end users. 1665 1666 ### Autoconf Details 1667 1668 The `configure` script is based on the autoconf framework, but in some details 1669 deviate from a normal autoconf `configure` script. 1670 1671 The `configure` script in the top level directory of OpenJDK is just a thin 1672 wrapper that calls `make/autoconf/configure`. This in turn will run `autoconf` 1673 to create the runnable (generated) configure script, as 1674 `.build/generated-configure.sh`. Apart from being responsible for the 1675 generation of the runnable script, the `configure` script also provides 1676 functionality that is not easily expressed in the normal Autoconf framework. As 1677 part of this functionality, the generated script is called. 1678 1679 The build system will detect if the Autoconf source files have changed, and 1680 will trigger a regeneration of the generated script if needed. You can also 1681 manually request such an update by `bash configure autogen`. 1682 1683 In previous versions of the OpenJDK, the generated script was checked in at 1684 `make/autoconf/generated-configure.sh`. This is no longer the case. 1685 1686 ### Developing the Build System Itself 1687 1688 This section contains a few remarks about how to develop for the build system 1689 itself. It is not relevant if you are only making changes in the product source 1690 code. 1691 1692 While technically using `make`, the make source files of the OpenJDK does not 1693 resemble most other Makefiles. Instead of listing specific targets and actions 1694 (perhaps using patterns), the basic modus operandi is to call a high-level 1695 function (or properly, macro) from the API in `make/common`. For instance, to 1696 compile all classes in the `jdk.internal.foo` package in the `jdk.foo` module, 1697 a call like this would be made: 1698 1699 ``` 1700 $(eval $(call SetupJavaCompilation, BUILD_FOO_CLASSES, \ 1701 SETUP := GENERATE_OLDBYTECODE, \ 1702 SRC := $(TOPDIR)/src/jkd.foo/share/classes, \ 1703 INCLUDES := jdk/internal/foo, \ 1704 BIN := $(SUPPORT_OUTPUTDIR)/foo_classes, \ 1705 )) 1706 ``` 1707 1708 By encapsulating and expressing the high-level knowledge of *what* should be 1709 done, rather than *how* it should be done (as is normal in Makefiles), we can 1710 build a much more powerful and flexible build system. 1711 1712 Correct dependency tracking is paramount. Sloppy dependency tracking will lead 1713 to improper parallelization, or worse, race conditions. 1714 1715 To test for/debug race conditions, try running `make JOBS=1` and `make 1716 JOBS=100` and see if it makes any difference. (It shouldn't). 1717 1718 To compare the output of two different builds and see if, and how, they differ, 1719 run `$BUILD1/compare.sh -o $BUILD2`, where `$BUILD1` and `$BUILD2` are the two 1720 builds you want to compare. 1721 1722 To automatically build two consecutive versions and compare them, use 1723 `COMPARE_BUILD`. The value of `COMPARE_BUILD` is a set of variable=value 1724 assignments, like this: 1725 ``` 1726 make COMPARE_BUILD=CONF=--enable-new-hotspot-feature:MAKE=hotspot 1727 ``` 1728 See `make/InitSupport.gmk` for details on how to use `COMPARE_BUILD`. 1729 1730 To analyze build performance, run with `LOG=trace` and check `$BUILD/build-trace-time.log`. 1731 Use `JOBS=1` to avoid parallelism. 1732 1733 Please check that you adhere to the [Code Conventions for the Build System]( 1734 http://openjdk.java.net/groups/build/doc/code-conventions.html) before 1735 submitting patches. 1736 1737 ## Contributing to OpenJDK 1738 1739 So, now you've build your OpenJDK, and made your first patch, and want to 1740 contribute it back to the OpenJDK community. 1741 1742 First of all: Thank you! We gladly welcome your contribution to the OpenJDK. 1743 However, please bear in mind that OpenJDK is a massive project, and we must ask 1744 you to follow our rules and guidelines to be able to accept your contribution. 1745 1746 The official place to start is the ['How to contribute' page]( 1747 http://openjdk.java.net/contribute/). There is also an official (but somewhat 1748 outdated and skimpy on details) [Developer's Guide]( 1749 http://openjdk.java.net/guide/). 1750 1751 If this seems overwhelming to you, the Adoption Group is there to help you! A 1752 good place to start is their ['New Contributor' page]( 1753 https://wiki.openjdk.java.net/display/Adoption/New+Contributor), or start 1754 reading the comprehensive [Getting Started Kit]( 1755 https://adoptopenjdk.gitbooks.io/adoptopenjdk-getting-started-kit/en/). The 1756 Adoption Group will also happily answer any questions you have about 1757 contributing. Contact them by [mail]( 1758 http://mail.openjdk.java.net/mailman/listinfo/adoption-discuss) or [IRC]( 1759 http://openjdk.java.net/irc/). 1760 1761 --- 1762 # Override styles from the base CSS file that are not ideal for this document. 1763 header-includes: 1764 - '<style type="text/css">pre, code, tt { color: #1d6ae5; }</style>' 1765 ---