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This is not an exhaustive list.</p> 95 <h3>Multiple Targets</h3> 96 <p>It needs to be possible to build the Android platform for multiple targets. 97 This means:</p> 98 <ul> 99 <li>The build system will support building tools for the host platform, 100 both ones that are used in the build process itself, and developer tools 101 like the simulator.</li> 102 <li>The build system will need to be able to build tools on Linux 103 (definitely Goobuntu and maybe Grhat), MacOS, and to some degree on 104 Windows.</li> 105 <li>The build system will need to be able to build the OS on Linux, and in 106 the short-term, MacOS. Note that this is a conscious decision to stop 107 building the OS on Windows. We are going to rely on the emulator there 108 and not attempt to use the simulator. This is a requirement change now 109 that the emulator story is looking brighter.</li> 110 </ul> 111 <h3>Non-Recursive Make</h3> 112 <p>To achieve the objectives, the build system will be rewritten to use make 113 non-recursively. For more background on this, read <a href="http://aegis.sourceforge.net/auug97.pdf">Recursive Make Considered Harmful</a>. For those that don't 114 want PDF, here is the 115 <a href="http://72.14.203.104/search?q=cache:HwuX7YF2uBIJ:aegis.sourceforge.net/auug97.pdf&hl=en&gl=us&ct=clnk&cd=2&client=firefox">Google translated version</a>. 116 <h3>Rapid Compile-Test Cycles</h3> 117 <p>When developing a component, for example a C++ shared library, it must be 118 possible to easily rebuild just that component, and not have to wait more than a 119 couple seconds for dependency checks, and not have to wait for unneeded 120 components to be built.</p> 121 <h3>Both Environment and Config File Based Settings</h3> 122 <p>To set the target, and other options, some people on the team like to have a 123 configuration file in a directory so they do not have an environment setup 124 script to run, and others want an environment setup script to run so they can 125 run builds in different terminals on the same tree, or switch back and forth 126 in one terminal. We will support both.</p> 127 <h3>Object File Directory / make clean</h3> 128 <p>Object files and other intermediate files will be generated into a directory 129 that is separate from the source tree. The goal is to have make clean be 130 "rm -rf <obj>" in the tree root directory. The primary goals of 131 this are to simplify searching the source tree, and to make "make clean" more 132 reliable.</p> 133 134 <h3>SDK</h3> 135 <p>The SDK will be a tarball that will allow non-OS-developers to write apps. 136 The apps will actually be built by first building the SDK, and then building 137 the apps against that SDK. This will hopefully (1) make writing apps easier 138 for us, because we won't have to rebuild the OS as much, and we can use the 139 standard java-app development tools, and (2) allow us to dog-food the SDK, to 140 help ensure its quality. Cedric has suggested (and I agree) that apps built 141 from the SDK should be built with ant. Stay tuned for more details as we 142 figure out exactly how this will work.</p> 143 144 <h3>Dependecies</h3> 145 <p>Dependencies should all be automatic. Unless there is a custom tool involved 146 (e.g. the webkit has several), the dependencies for shared and static libraries, 147 .c, .cpp, .h, .java, java libraries, etc., should all work without intervention 148 in the Android.mk file.</p> 149 150 <h3>Hiding command lines</h3> 151 <p>The default of the build system will be to hide the command lines being 152 executed for make steps. It will be possible to override this by specifying 153 the showcommands pseudo-target, and possibly by setting an environment 154 variable.</p> 155 156 <h3>Wildcard source files</h3> 157 <p>Wildcarding source file will be discouraged. It may be useful in some 158 scenarios. The default <code>$(wildcard *)</code> will not work due to the 159 current directory being set to the root of the build tree.<p> 160 161 <h3>Multiple targets in one directory</h3> 162 <p>It will be possible to generate more than one target from a given 163 subdirectory. For example, libutils generates a shared library for the target 164 and a static library for the host.</p> 165 166 <h3>Makefile fragments for modules</h3> 167 <p><b>Android.mk</b> is the standard name for the makefile fragments that 168 control the building of a given module. Only the top directory should 169 have a file named "Makefile".</p> 170 171 <h3>Use shared libraries</h3> 172 <p>Currently, the simulator is not built to use shared libraries. This should 173 be fixed, and now is a good time to do it. This implies getting shared 174 libraries to work on Mac OS.</p> 175 176 177 <h2>Nice to Have</h2> 178 179 <p>These things would be nice to have, and this is a good place to record them, 180 however these are not promises.</p> 181 182 <h3>Simultaneous Builds</h3> 183 <p>The hope is to be able to do two builds for different combos in the same 184 tree at the same time, but this is a stretch goal, not a requirement. 185 Doing two builds in the same tree, not at the same time must work. (update: 186 it's looking like we'll get the two builds at the same time working)</p> 187 188 <h3>Deleting headers (or other dependecies)</h3> 189 <p>Problems can arise if you delete a header file that is referenced in 190 ".d" files. The easy way to deal with this is "make clean". There 191 should be a better way to handle it. (from fadden)</p> 192 <p>One way of solving this is introducing a dependency on the directory. The 193 problem is that this can create extra dependecies and slow down the build. 194 It's a tradeoff.</p> 195 196 <h3>Multiple builds</h3> 197 <p>General way to perform builds across the set of known platforms. This 198 would make it easy to perform multiple platform builds when testing a 199 change, and allow a wide-scale "make clean". Right now the buildspec.mk 200 or environment variables need to be updated before each build. (from fadden)</p> 201 202 <h3>Aftermarket Locales and Carrier</h3> 203 <p>We will eventually need to add support for creating locales and carrier 204 customizations to the SDK, but that will not be addressed right now.</p> 205 206 207 <h2><a id="usage"/>Usage</h2> 208 <p>You've read (or scrolled past) all of the motivations for this build system, 209 and you want to know how to use it. This is the place.</p> 210 211 <h3>Your first build</h3> 212 <p>The <a href="../building.html">Building</a> document describes how do do 213 builds.</p> 214 215 <h3>build/envsetup.sh functions</h3> 216 If you source the file build/envsetup.sh into your bash environment, 217 <code>. build/envsetup.sh</code>you'll get a few helpful shell functions: 218 219 <ul> 220 <li><b>printconfig</b> - Prints the current configuration as set by the 221 lunch and choosecombo commands.</li> 222 <li><b>m</b> - Runs <code>make</code> from the top of the tree. This is 223 useful because you can run make from within subdirectories. If you have the 224 <code>TOP</code> environment variable set, it uses that. If you don't, it looks 225 up the tree from the current directory, trying to find the top of the tree.</li> 226 <li><b>croot</b> - <code>cd</code> to the top of the tree.</li> 227 <li><b>sgrep</b> - grep for the regex you provide in all .c, .cpp, .h, .java, 228 and .xml files below the current directory.</li> 229 </ul> 230 231 <h3>Build flavors/types</h3> 232 <p> 233 When building for a particular product, it's often useful to have minor 234 variations on what is ultimately the final release build. These are the 235 currently-defined "flavors" or "types" (we need to settle on a real name 236 for these). 237 </p> 238 239 <table border=1> 240 <tr> 241 <td> 242 <code>eng<code> 243 </td> 244 <td> 245 This is the default flavor. A plain "<code>make</code>" is the 246 same as "<code>make eng</code>". <code>droid</code> is an alias 247 for <code>eng</code>. 248 <ul> 249 <li>Installs modules tagged with: <code>eng</code>, <code>debug</code>, 250 <code>shell_</code>$(TARGET_SHELL), 251 <code>user</code>, and/or <code>development</code>. 252 <li>Installs non-APK modules that have no tags specified. 253 <li>Installs APKs according to the product definition files, in 254 addition to tagged APKs. 255 <li><code>ro.secure=0</code> 256 <li><code>ro.debuggable=1</code> 257 <li><code>ro.kernel.android.checkjni=1</code> 258 <li><code>adb</code> is enabled by default. 259 </td> 260 </tr> 261 <tr> 262 <td> 263 <code>user<code> 264 </td> 265 <td> 266 "<code>make user</code>" 267 <p> 268 This is the flavor intended to be the final release bits. 269 <ul> 270 <li>Installs modules tagged with <code>shell_</code>$(TARGET_SHELL) and <code>user</code>. 271 <li>Installs non-APK modules that have no tags specified. 272 <li>Installs APKs according to the product definition files; tags 273 are ignored for APK modules. 274 <li><code>ro.secure=1</code> 275 <li><code>ro.debuggable=0</code> 276 <li><code>adb</code> is disabled by default. 277 </td> 278 </tr> 279 <tr> 280 <td> 281 <code>userdebug<code> 282 </td> 283 <td> 284 "<code>make userdebug</code>" 285 <p> 286 The same as <code>user</code>, except: 287 <ul> 288 <li>Also installs modules tagged with <code>debug</code>. 289 <li><code>ro.debuggable=1</code> 290 <li><code>adb</code> is enabled by default. 291 </td> 292 </tr> 293 </table> 294 295 <p> 296 If you build one flavor and then want to build another, you should run 297 "<code>make installclean</code>" between the two makes to guarantee that 298 you don't pick up files installed by the previous flavor. "<code>make 299 clean</code>" will also suffice, but it takes a lot longer. 300 </p> 301 302 303 <h3>More pseudotargets</h3> 304 <p>Sometimes you want to just build one thing. The following pseudotargets are 305 there for your convenience:</p> 306 307 <ul> 308 <li><b>droid</b> - <code>make droid</code> is the normal build. This target 309 is here because the default target has to have a name.</li> 310 <li><b>all</b> - <code>make all</code> builds everything <code>make 311 droid</code> does, plus everything whose <code>LOCAL_MODULE_TAGS</code> do not 312 include the "droid" tag. The build server runs this to make sure 313 that everything that is in the tree and has an Android.mk builds.</li> 314 <li><b>clean-$(LOCAL_MODULE)</b> and <b>clean-$(LOCAL_PACKAGE_NAME)</b> - 315 Let you selectively clean one target. For example, you can type 316 <code>make clean-libutils</code> and it will delete libutils.so and all of the 317 intermediate files, or you can type <code>make clean-Home</code> and it will 318 clean just the Home app.</li> 319 <li><b>clean</b> - <code>make clean</code> deletes all of the output and 320 intermediate files for this configuration. This is the same as <code>rm -rf 321 out/<configuration>/</code></li> 322 <li><b>clobber</b> - <code>make clobber</code> deletes all of the output 323 and intermediate files for all configurations. This is the same as 324 <code>rm -rf out/</code>.</li> 325 <li><b>dataclean</b> - <code>make dataclean</code> deletes contents of the data 326 directory inside the current combo directory. This is especially useful on the 327 simulator and emulator, where the persistent data remains present between 328 builds.</li> 329 <li><b>showcommands</b> - <code>showcommands</code> is a modifier target 330 which causes the build system to show the actual command lines for the build 331 steps, instead of the brief descriptions. Most people don't like seeing the 332 actual commands, because they're quite long and hard to read, but if you need 333 to for debugging purposes, you can add <code>showcommands</code> to the list 334 of targets you build. For example <code>make showcommands</code> will build 335 the default android configuration, and <code>make runtime showcommands</code> 336 will build just the runtime, and targets that it depends on, while displaying 337 the full command lines. Please note that there are a couple places where the 338 commands aren't shown here. These are considered bugs, and should be fixed, 339 but they're often hard to track down. Please let 340 <a href="mailto:android-build-team">android-build-team</a> know if you find 341 any.</li> 342 <li><b>LOCAL_MODULE</b> - Anything you specify as a <code>LOCAL_MODULE</code> 343 in an Android.mk is made into a pseudotarget. For example, <code>make 344 runtime</code> might be shorthand for <code>make 345 out/linux-x86-debug/system/bin/runtime</code> (which would work), and 346 <code>make libkjs</code> might be shorthand for <code>make 347 out/linux-x86-debug/system/lib/libkjs.so</code> (which would also work).</li> 348 <li><b>targets</b> - <code>make targets</code> will print a list of all of 349 the LOCAL_MODULE names you can make.</li> 350 </ul> 351 352 <h3><a name="templates"/>How to add another component to the build - Android.mk templates</h3> 353 <p>You have a new library, a new app, or a new executable. For each of the 354 common types of modules, there is a corresponding file in the templates 355 directory. It will usually be enough to copy one of these, and fill in your 356 own values. Some of the more esoteric values are not included in the 357 templates, but are instead just documented here, as is the documentation 358 on using custom tools to generate files.</p> 359 <p>Mostly, you can just look for the TODO comments in the templates and do 360 what it says. Please remember to delete the TODO comments when you're done 361 to keep the files clean. The templates have minimal documentation in them, 362 because they're going to be copied, and when that gets stale, the copies just 363 won't get updated. So read on...</p> 364 365 <h4>Apps</h4> 366 <p>Use the <code>templates/apps</code> file.</p> 367 <p>This template is pretty self-explanitory. See the variables below for more 368 details.</p> 369 370 <h4>Java Libraries</h4> 371 <p>Use the <code>templates/java_library</code> file.</p> 372 <p>The interesting thing here is the value of LOCAL_MODULE, which becomes 373 the name of the jar file. (Actually right now, we're not making jar files yet, 374 just directories of .class files, but the directory is named according to 375 what you put in LOCAL_MODULE). This name will be what goes in the 376 LOCAL_JAVA_LIBRARIES variable in modules that depend on your java library.</p> 377 378 <h4>C/C++ Executables</h4> 379 <p>Use the <code>templates/executable</code> file, or the 380 <code>templates/executable_host</code> file.</p> 381 <p>This template has a couple extra options that you usually don't need. 382 Please delete the ones you don't need, and remove the TODO comments. It makes 383 the rest of them easier to read, and you can always refer back to the templates 384 if you need them again later.</p> 385 <p>By default, on the target these are built into /system/bin, and on the 386 host, they're built into <combo>/host/bin. These can be overridden by setting 387 <code>LOCAL_MODULE_PATH</code>. See 388 <a href="#moving-targets">Putting targets elsewhere</a> 389 for more.</p> 390 391 <h4>Shared Libraries</h4> 392 <p>Use the <code>templates/shared_library</code> file, or the 393 <code>templates/shared_library_host</code> file.</p> 394 <p>Remember that on the target, we use shared libraries, and on the host, 395 we use static libraries, since executable size isn't as big an issue, and it 396 simplifies distribution in the SDK.</p> 397 398 <h4>Static Libraries</h4> 399 <p>Use the <code>templates/static_library</code> file, or the 400 <code>templates/static_library_host</code> file.</p> 401 <p>Remember that on the target, we use shared libraries, and on the host, 402 we use static libraries, since executable size isn't as big an issue, and it 403 simplifies distribution in the SDK.</p> 404 405 <h4><a name="custom-tools"/>Using Custom Tools</h4> 406 <p>If you have a tool that generates source files for you, it's possible 407 to have the build system get the dependencies correct for it. Here are 408 a couple of examples. <code>$@</code> is the make built-in variable for 409 "the current target." The <font color=red>red</font> parts are the parts you'll 410 need to change.</p> 411 412 <p>You need to put this after you have declared <code>LOCAL_PATH</code> and 413 <code>LOCAL_MODULE</code>, because the <code>$(local-intermediates-dir)</code> 414 and <code>$(local-host-intermediates-dir)</code> macros use these variables 415 to determine where to put the files. 416 417 <h5>Example 1</h5> 418 <p>Here, there is one generated file, called 419 chartables.c, which doesn't depend on anything. And is built by the tool 420 built to $(HOST_OUT_EXECUTABLES)/dftables. Note on the second to last line 421 that a dependency is created on the tool.</p> 422 <pre> 423 intermediates:= $(local-intermediates-dir) 424 GEN := $(intermediates)/<font color=red>chartables.c</font> 425 $(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>$(HOST_OUT_EXECUTABLES)/dftables $@</font> 426 $(GEN): <font color=red>$(HOST_OUT_EXECUTABLES)/dftables</font> 427 $(transform-generated-source) 428 LOCAL_GENERATED_SOURCES += $(GEN) 429 </pre> 430 431 <h5>Example 2</h5> 432 <p>Here as a hypothetical example, we use use cat as if it were to transform 433 a file. Pretend that it does something useful. Note how we use a 434 target-specific variable called PRIVATE_INPUT_FILE to store the name of the 435 input file.</p> 436 <pre> 437 intermediates:= $(local-intermediates-dir) 438 GEN := $(intermediates)/<font color=red>file.c</font> 439 $(GEN): PRIVATE_INPUT_FILE := $(LOCAL_PATH)/<font color=red>input.file</font> 440 $(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>cat $(PRIVATE_INPUT_FILE) > $@</font> 441 $(GEN): <font color=red>$(LOCAL_PATH)/file.c</font> 442 $(transform-generated-source) 443 LOCAL_GENERATED_SOURCES += $(GEN) 444 </pre> 445 446 <h5>Example 3</h5> 447 <p>If you have several files that are all similar in 448 name, and use the same tool, you can combine them. (here the *.lut.h files are 449 the generated ones, and the *.cpp files are the input files)</p> 450 <pre> 451 intermediates:= $(local-intermediates-dir) 452 GEN := $(addprefix $(intermediates)<font color=red>/kjs/, \ 453 array_object.lut.h \ 454 bool_object.lut.h \</font> 455 ) 456 $(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>perl libs/WebKitLib/WebKit/JavaScriptCore/kjs/create_hash_table $< -i > $@</font> 457 $(GEN): $(intermediates)/<font color=red>%.lut.h</font> : $(LOCAL_PATH)/<font color=red>%.cpp</font> 458 $(transform-generated-source) 459 LOCAL_GENERATED_SOURCES += $(GEN) 460 </pre> 461 462 <h3><a name="platform-specific"/>Platform specific conditionals</h3> 463 <p>Sometimes you need to set flags specifically for different platforms. Here 464 is a list of which values the different build-system defined variables will be 465 set to and some examples.</p> 466 <p>For a device build, <code>TARGET_OS</code> is <code>linux</code> (we're using 467 linux!), and <code>TARGET_ARCH</code> is <code>arm</code>.</p> 468 <p>For a simulator build, <code>TARGET_OS</code> and <code>TARGET_ARCH</code> 469 are set to the same as <code>HOST_OS</code> and <code>HOST_ARCH</code> are 470 on your platform. <code>TARGET_PRODUCT</code> is the name of the target 471 hardware/product you are building for. The value <code>sim</code> is used 472 for the simulator. We haven't thought through the full extent of customization 473 that will happen here, but likely there will be additional UI configurations 474 specified here as well.</p> 475 <table cellspacing=25> 476 <tr> 477 <td valign=top align=center> 478 <b>HOST_OS</b><br/> 479 linux<br/> 480 darwin<br/> 481 (cygwin) 482 </td> 483 <td valign=top align=center> 484 <b>HOST_ARCH</b><br/> 485 x86 486 </td> 487 <td valign=top align=center> 488 <b>HOST_BUILD_TYPE</b><br/> 489 release<br/> 490 debug 491 </td> 492 </tr> 493 <tr> 494 <td valign=top align=center> 495 <b>TARGET_OS</b><br/> 496 linux<br/> 497 darwin<br/> 498 (cygwin) 499 </td> 500 <td valign=top align=center> 501 <b>TARGET_ARCH</b><br/> 502 arm<br/> 503 x86 504 </td> 505 <td valign=top align=center> 506 <b>TARGET_BUILD_TYPE</b><br/> 507 release<br/> 508 debug 509 </td> 510 <td valign=top align=center> 511 <b>TARGET_PRODUCT</b><br/> 512 sim<br/> 513 dream<br/> 514 sooner 515 </td> 516 </tr> 517 </table> 518 519 <h4>Some Examples</h4> 520 <pre>ifeq ($(TARGET_BUILD_TYPE),release) 521 LOCAL_CFLAGS += -DNDEBUG=1 522 endif 523 524 # from libutils 525 ifeq ($(TARGET_OS),linux) 526 # Use the futex based mutex and condition variable 527 # implementation from android-arm because it's shared mem safe 528 LOCAL_SRC_FILES += futex_synchro.c 529 LOCAL_LDLIBS += -lrt -ldl 530 endif 531 532 </pre> 533 534 535 <h3><a name="moving-modules"/>Putting modules elsewhere</h3> 536 <p>If you have modules that normally go somewhere, and you need to have them 537 build somewhere else, read this. One use of this is putting files on 538 the root filesystem instead of where they normally go in /system. Add these 539 lines to your Android.mk:</p> 540 <pre> 541 LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN) 542 LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED) 543 </pre> 544 <p>For executables and libraries, you need to also specify a 545 <code>LOCAL_UNSTRIPPED_PATH</code> location, because on target builds, we keep 546 the unstripped executables so GDB can find the symbols.</code> 547 <p>Look in <code>config/envsetup.make</code> for all of the variables defining 548 places to build things.</p> 549 <p>FYI: If you're installing an executable to /sbin, you probably also want to 550 set <code>LOCAL_FORCE_STATIC_EXCUTABLE := true</code> in your Android.mk, which 551 will force the linker to only accept static libraries.</p> 552 553 554 <h3>Android.mk variables</h3> 555 <p>These are the variables that you'll commonly see in Android.mk files, listed 556 alphabetically.</p> 557 <p>But first, a note on variable naming: 558 <ul> 559 <li><b>LOCAL_</b> - These variables are set per-module. They are cleared 560 by the <code>include $(CLEAR_VARS)</code> line, so you can rely on them 561 being empty after including that file. Most of the variables you'll use 562 in most modules are LOCAL_ variables.</li> 563 <li><b>PRIVATE_</b> - These variables are make-target-specific variables. That 564 means they're only usable within the commands for that module. It also 565 means that they're unlikely to change behind your back from modules that 566 are included after yours. This 567 <a href="http://www.gnu.org/software/make/manual/make.html#Target_002dspecific">link to the make documentation</a> 568 describes more about target-specific variables. Please note that there 569 are a couple of these laying around the tree that aren't prefixed with 570 PRIVATE_. It is safe, and they will be fixed as they are discovered. 571 Sorry for the confusion.</li> 572 <li><b>INTERNAL_</b> - These variables are critical to functioning of 573 the build system, so you shouldn't create variables named like this, and 574 you probably shouldn't be messing with these variables in your makefiles. 575 </li> 576 <li><b>HOST_</b> and <b>TARGET_</b> - These contain the directories 577 and definitions that are specific to either the host or the target builds. 578 Do not set variables that start with HOST_ or TARGET_ in your makefiles. 579 </li> 580 <li><b>BUILD_</b> and <b>CLEAR_VARS</b> - These contain the names of 581 well-defined template makefiles to include. Some examples are CLEAR_VARS 582 and BUILD_HOST_PACKAGE.</li> 583 <li>Any other name is fair-game for you to use in your Android.mk. However, 584 remember that this is a non-recursive build system, so it is possible that 585 your variable will be changed by another Android.mk included later, and be 586 different when the commands for your rule / module are executed.</li> 587 </ul> 588 </p> 589 590 <h4>LOCAL_ASSET_FILES</h4> 591 <p>In Android.mk files that <code>include $(BUILD_PACKAGE)</code> set this 592 to the set of files you want built into your app. Usually:</p> 593 <p><code>LOCAL_ASSET_FILES += $(call find-subdir-assets)</code></p> 594 <p>This will probably change when we switch to ant for the apps' build 595 system.</p> 596 597 <h4>LOCAL_CC</h4> 598 <p>If you want to use a different C compiler for this module, set LOCAL_CC 599 to the path to the compiler. If LOCAL_CC is blank, the appropriate default 600 compiler is used.</p> 601 602 <h4>LOCAL_CXX</h4> 603 <p>If you want to use a different C++ compiler for this module, set LOCAL_CXX 604 to the path to the compiler. If LOCAL_CXX is blank, the appropriate default 605 compiler is used.</p> 606 607 <h4>LOCAL_CFLAGS</h4> 608 <p>If you have additional flags to pass into the C or C++ compiler, add 609 them here. For example:</p> 610 <p><code>LOCAL_CFLAGS += -DLIBUTILS_NATIVE=1</code></p> 611 612 <h4>LOCAL_CPPFLAGS</h4> 613 <p>If you have additional flags to pass into <i>only</i> the C++ compiler, add 614 them here. For example:</p> 615 <p><code>LOCAL_CPPFLAGS += -ffriend-injection</code></p> 616 <code>LOCAL_CPPFLAGS</code> is guaranteed to be after <code>LOCAL_CFLAGS</code> 617 on the compile line, so you can use it to override flags listed in 618 <code>LOCAL_CFLAGS</code>. 619 620 <h4>LOCAL_CPP_EXTENSION</h4> 621 <p>If your C++ files end in something other than "<code>.cpp</code>", 622 you can specify the custom extension here. For example:</p> 623 <p><code>LOCAL_CPP_EXTENSION := .cc</code></p> 624 Note that all C++ files for a given module must have the same 625 extension; it is not currently possible to mix different extensions. 626 627 <h4>LOCAL_NO_DEFAULT_COMPILER_FLAGS</h4> 628 <p>Normally, the compile line for C and C++ files includes global include 629 paths and global cflags. If <code>LOCAL_NO_DEFAULT_COMPILER_FLAGS</code> 630 is non-empty, none of the default includes or flags will be used when compiling 631 C and C++ files in this module. 632 <code>LOCAL_C_INCLUDES</code>, <code>LOCAL_CFLAGS</code>, and 633 <code>LOCAL_CPPFLAGS</code> will still be used in this case, as will 634 any <code>DEBUG_CFLAGS</code> that are defined for the module. 635 636 <h4>LOCAL_COPY_HEADERS</h4> 637 <p class=warning>This will be going away.</p> 638 <p>The set of files to copy to the install include tree. You must also 639 supply <code>LOCAL_COPY_HEADERS_TO</code>.</p> 640 <p>This is going away because copying headers messes up the error messages, and 641 may lead to people editing those headers instead of the correct ones. It also 642 makes it easier to do bad layering in the system, which we want to avoid. We 643 also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any 644 headers.</p> 645 646 <h4>LOCAL_COPY_HEADERS_TO</h4> 647 <p class=warning>This will be going away.</p> 648 <p>The directory within "include" to copy the headers listed in 649 <code>LOCAL_COPY_HEADERS</code> to.</p> 650 <p>This is going away because copying headers messes up the error messages, and 651 may lead to people editing those headers instead of the correct ones. It also 652 makes it easier to do bad layering in the system, which we want to avoid. We 653 also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any 654 headers.</p> 655 656 <h4>LOCAL_C_INCLUDES</h4> 657 <p>Additional directories to instruct the C/C++ compilers to look for header 658 files in. These paths are rooted at the top of the tree. Use 659 <code>LOCAL_PATH</code> if you have subdirectories of your own that you 660 want in the include paths. For example:</p> 661 <p><code> 662 LOCAL_C_INCLUDES += extlibs/zlib-1.2.3<br/> 663 LOCAL_C_INCLUDES += $(LOCAL_PATH)/src 664 </code></p> 665 <p>You should not add subdirectories of include to 666 <code>LOCAL_C_INCLUDES</code>, instead you should reference those files 667 in the <code>#include</code> statement with their subdirectories. For 668 example:</p> 669 <p><code>#include <utils/KeyedVector.h></code><br/> 670 not <code><s>#include <KeyedVector.h></s></code></p> 671 <p>There are some components that are doing this wrong, and should be cleaned 672 up.</p> 673 674 <h4>LOCAL_MODULE_TAGS</h4> 675 <p>Set <code>LOCAL_MODULE_TAGS</code> to any number of whitespace-separated 676 tags. If the tag list is empty or contains <code>droid</code>, the module 677 will get installed as part of a <code>make droid</code>. Modules with the tag 678 <code>shell_</code>$(TARGET_SHELL) will also be installed. Otherwise, it will 679 only get installed by running <code>make <your-module></code> 680 or with the <code>make all</code> pseudotarget.</p> 681 682 <h4>LOCAL_REQUIRED_MODULES</h4> 683 <p>Set <code>LOCAL_REQUIRED_MODULES</code> to any number of whitespace-separated 684 module names, like "libblah" or "Email". If this module is installed, all 685 of the modules that it requires will be installed as well. This can be 686 used to, e.g., ensure that necessary shared libraries or providers are 687 installed when a given app is installed. 688 689 <h4>LOCAL_FORCE_STATIC_EXECUTABLE</h4> 690 <p>If your executable should be linked statically, set 691 <code>LOCAL_FORCE_STATIC_EXECUTABLE:=true</code>. There is a very short 692 list of libraries that we have in static form (currently only libc). This is 693 really only used for executables in /sbin on the root filesystem.</p> 694 695 <h4>LOCAL_GENERATED_SOURCES</h4> 696 <p>Files that you add to <code>LOCAL_GENERATED_SOURCES</code> will be 697 automatically generated and then linked in when your module is built. 698 See the <a href="#custom-tools">Custom Tools</a> template makefile for an 699 example.</p> 700 701 <h4>LOCAL_JAVACFLAGS</h4> 702 <p>If you have additional flags to pass into the javac compiler, add 703 them here. For example:</p> 704 <p><code>LOCAL_JAVACFLAGS += -Xlint:deprecation</code></p> 705 706 <h4>LOCAL_JAVA_LIBRARIES</h4> 707 <p>When linking Java apps and libraries, <code>LOCAL_JAVA_LIBRARIES</code> 708 specifies which sets of java classes to include. Currently there are 709 two of these: <code>core</code> and <code>framework</code>. 710 In most cases, it will look like this:</p> 711 <p><code>LOCAL_JAVA_LIBRARIES := core framework</code></p> 712 <p>Note that setting <code>LOCAL_JAVA_LIBRARIES</code> is not necessary 713 (and is not allowed) when building an APK with 714 "<code>include $(BUILD_PACKAGE)</code>". The appropriate libraries 715 will be included automatically.</p> 716 717 <h4>LOCAL_LDFLAGS</h4> 718 <p>You can pass additional flags to the linker by setting 719 <code>LOCAL_LDFLAGS</code>. Keep in mind that the order of parameters is 720 very important to ld, so test whatever you do on all platforms.</p> 721 722 <h4>LOCAL_LDLIBS</h4> 723 <p><code>LOCAL_LDLIBS</code> allows you to specify additional libraries 724 that are not part of the build for your executable or library. Specify 725 the libraries you want in -lxxx format; they're passed directly to the 726 link line. However, keep in mind that there will be no dependency generated 727 for these libraries. It's most useful in simulator builds where you want 728 to use a library preinstalled on the host. The linker (ld) is a particularly 729 fussy beast, so it's sometimes necessary to pass other flags here if you're 730 doing something sneaky. Some examples:</p> 731 <p><code>LOCAL_LDLIBS += -lcurses -lpthread<br/> 732 LOCAL_LDLIBS += -Wl,-z,origin 733 </code></p> 734 735 <h4>LOCAL_NO_MANIFEST</h4> 736 <p>If your package doesn't have a manifest (AndroidManifest.xml), then 737 set <code>LOCAL_NO_MANIFEST:=true</code>. The common resources package 738 does this.</p> 739 740 <h4>LOCAL_PACKAGE_NAME</h4> 741 <p><code>LOCAL_PACKAGE_NAME</code> is the name of an app. For example, 742 Dialer, Contacts, etc. This will probably change or go away when we switch 743 to an ant-based build system for the apps.</p> 744 745 <h4>LOCAL_PATH</h4> 746 <p>The directory your Android.mk file is in. You can set it by putting the 747 following as the first line in your Android.mk:</p> 748 <p><code>LOCAL_PATH := $(my-dir)</code></p> 749 <p>The <code>my-dir</code> macro uses the 750 <code><a href="http://www.gnu.org/software/make/manual/make.html#MAKEFILE_005fLIST-Variable">MAKEFILE_LIST</a></code> 751 variable, so you must call it before you include any other makefiles. Also, 752 consider that any subdirectories you inlcude might reset LOCAL_PATH, so do your 753 own stuff before you include them. This also means that if you try to write 754 several <code>include</code> lines that reference <code>LOCAL_PATH</code>, 755 it won't work, because those included makefiles might reset LOCAL_PATH. 756 757 <h4>LOCAL_POST_PROCESS_COMMAND</h4> 758 <p>For host executables, you can specify a command to run on the module 759 after it's been linked. You might have to go through some contortions 760 to get variables right because of early or late variable evaluation:</p> 761 <p><code>module := $(HOST_OUT_EXECUTABLES)/$(LOCAL_MODULE)<br/> 762 LOCAL_POST_PROCESS_COMMAND := /Developer/Tools/Rez -d __DARWIN__ -t APPL\<br/> 763 -d __WXMAC__ -o $(module) Carbon.r 764 </code></p> 765 766 <h4>LOCAL_PREBUILT_EXECUTABLES</h4> 767 <p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to 768 executables that you want copied. They're located automatically into the 769 right bin directory.</p> 770 771 <h4>LOCAL_PREBUILT_LIBS</h4> 772 <p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to 773 libraries that you want copied. They're located automatically into the 774 right lib directory.</p> 775 776 <h4>LOCAL_SHARED_LIBRARIES</h4> 777 <p>These are the libraries you directly link against. You don't need to 778 pass transitively included libraries. Specify the name without the suffix:</p> 779 <p><code>LOCAL_SHARED_LIBRARIES := \<br/> 780 libutils \<br/> 781 libui \<br/> 782 libaudio \<br/> 783 libexpat \<br/> 784 libsgl 785 </code></p> 786 787 <h4>LOCAL_SRC_FILES</h4> 788 <p>The build system looks at <code>LOCAL_SRC_FILES</code> to know what source 789 files to compile -- .cpp .c .y .l .java. For lex and yacc files, it knows 790 how to correctly do the intermediate .h and .c/.cpp files automatically. If 791 the files are in a subdirectory of the one containing the Android.mk, prefix 792 them with the directory name:</p> 793 <p><code>LOCAL_SRC_FILES := \<br/> 794 file1.cpp \<br/> 795 dir/file2.cpp 796 </code></p> 797 798 <h4>LOCAL_STATIC_LIBRARIES</h4> 799 <p>These are the static libraries that you want to include in your module. 800 Mostly, we use shared libraries, but there are a couple of places, like 801 executables in sbin and host executables where we use static libraries instead. 802 <p><code>LOCAL_STATIC_LIBRARIES := \<br/> 803 libutils \<br/> 804 libtinyxml 805 </code></p> 806 807 <h4>LOCAL_MODULE</h4> 808 <p><code>LOCAL_MODULE</code> is the name of what's supposed to be generated 809 from your Android.mk. For exmample, for libkjs, the <code>LOCAL_MODULE</code> 810 is "libkjs" (the build system adds the appropriate suffix -- .so .dylib .dll). 811 For app modules, use <code>LOCAL_PACKAGE_NAME</code> instead of 812 <code>LOCAL_MODULE</code>. We're planning on switching to ant for the apps, 813 so this might become moot.</p> 814 815 <h4>LOCAL_MODULE_PATH</h4> 816 <p>Instructs the build system to put the module somewhere other than what's 817 normal for its type. If you override this, make sure you also set 818 <code>LOCAL_UNSTRIPPED_PATH</code> if it's an executable or a shared library 819 so the unstripped binary has somewhere to go. An error will occur if you forget 820 to.</p> 821 <p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p> 822 823 <h4>LOCAL_UNSTRIPPED_PATH</h4> 824 <p>Instructs the build system to put the unstripped version of the module 825 somewhere other than what's normal for its type. Usually, you override this 826 because you overrode <code>LOCAL_MODULE_PATH</code> for an executable or a 827 shared library. If you overrode <code>LOCAL_MODULE_PATH</code>, but not 828 <code>LOCAL_UNSTRIPPED_PATH</code>, an error will occur.</p> 829 <p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p> 830 831 <h4>LOCAL_WHOLE_STATIC_LIBRARIES</h4> 832 <p>These are the static libraries that you want to include in your module without allowing 833 the linker to remove dead code from them. This is mostly useful if you want to add a static library 834 to a shared library and have the static library's content exposed from the shared library. 835 <p><code>LOCAL_WHOLE_STATIC_LIBRARIES := \<br/> 836 libsqlite3_android<br/> 837 </code></p> 838 839 <h4>LOCAL_YACCFLAGS</h4> 840 <p>Any flags to pass to invocations of yacc for your module. A known limitation 841 here is that the flags will be the same for all invocations of YACC for your 842 module. This can be fixed. If you ever need it to be, just ask.</p> 843 <p><code>LOCAL_YACCFLAGS := -p kjsyy</code></p> 844 845 846 847 <h2>Implementation Details</h2> 848 849 <p>You should never have to touch anything in the config directory unless 850 you're adding a new platform, new tools, or adding new features to the 851 build system. In general, please consult with the build system owner(s) 852 (<a href="mailto:android-build-team">android-build-team</a>) before you go 853 mucking around in here. That said, here are some notes on what's going on 854 under the hood.</p> 855 856 <h3>Environment Setup / buildspec.mk Versioning</h3> 857 <p>In order to make easier for people when the build system changes, when 858 it is necessary to make changes to buildspec.mk or to rerun the environment 859 setup scripts, they contain a version number in the variable 860 BUILD_ENV_SEQUENCE_NUMBER. If this variable does not match what the build 861 system expects, it fails printing an error message explaining what happened. 862 If you make a change that requires an update, you need to update two places 863 so this message will be printed. 864 <ul> 865 <li>In config/envsetup.make, increment the 866 CORRECT_BUILD_ENV_SEQUENCE_NUMBER definition.</li> 867 <li>In buildspec.mk.default, update the BUILD_ENV_SEQUENCE_DUMBER 868 definition to match the one in config/envsetup.make</li> 869 </ul> 870 The scripts automatically get the value from the build system, so they will 871 trigger the warning as well. 872 </p> 873 874 <h3>Additional makefile variables</h3> 875 <p>You probably shouldn't use these variables. Please consult 876 <a href="mailto:android-build-team">android-build-team</a> before using them. 877 These are mostly there for workarounds for other issues, or things that aren't 878 completely done right.</p> 879 880 <h4>LOCAL_ADDITIONAL_DEPENDENCIES</h4> 881 <p>If your module needs to depend on anything else that 882 isn't actually built in to it, you can add those make targets to 883 <code>LOCAL_ADDITIONAL_DEPENDENCIES</code>. Usually this is a workaround 884 for some other dependency that isn't created automatically.</p> 885 886 <h4>LOCAL_BUILT_MODULE</h4> 887 <p>When a module is built, the module is created in an intermediate 888 directory then copied to its final location. LOCAL_BUILT_MODULE is 889 the full path to the intermediate file. See LOCAL_INSTALLED_MODULE 890 for the path to the final installed location of the module.</p> 891 892 <h4>LOCAL_HOST</h4> 893 <p>Set by the host_xxx.make includes to tell base_rules.make and the other 894 includes that we're building for the host. Kenneth did this as part of 895 openbinder, and I would like to clean it up so the rules, includes and 896 definitions aren't duplicated for host and target.</p> 897 898 <h4>LOCAL_INSTALLED_MODULE</h4> 899 <p>The fully qualified path name of the final location of the module. 900 See LOCAL_BUILT_MODULE for the location of the intermediate file that 901 the make rules should actually be constructing.</p> 902 903 <h4>LOCAL_REPLACE_VARS</h4> 904 <p>Used in some stuff remaining from the openbinder for building scripts 905 with particular values set,</p> 906 907 <h4>LOCAL_SCRIPTS</h4> 908 <p>Used in some stuff remaining from the openbinder build system that we 909 might find handy some day.</p> 910 911 <h4>LOCAL_MODULE_CLASS</h4> 912 <p>Which kind of module this is. This variable is used to construct other 913 variable names used to locate the modules. See base_rules.make and 914 envsetup.make.</p> 915 916 <h4>LOCAL_MODULE_NAME</h4> 917 <p>Set to the leaf name of the LOCAL_BUILT_MODULE. I'm not sure, 918 but it looks like it's just used in the WHO_AM_I variable to identify 919 in the pretty printing what's being built.</p> 920 921 <h4>LOCAL_MODULE_SUFFIX</h4> 922 <p>The suffix that will be appended to <code>LOCAL_MODULE</code> to form 923 <code>LOCAL_MODULE_NAME</code>. For example, .so, .a, .dylib.</p> 924 925 <h4>LOCAL_STRIP_MODULE</h4> 926 <p>Calculated in base_rules.make to determine if this module should actually 927 be stripped or not, based on whether <code>LOCAL_STRIPPABLE_MODULE</code> 928 is set, and whether the combo is configured to ever strip modules. With 929 Iliyan's stripping tool, this might change.</p> 930 931 <h4>LOCAL_STRIPPABLE_MODULE</h4> 932 <p>Set by the include makefiles if that type of module is strippable. 933 Executables and shared libraries are.</p> 934 935 <h4>LOCAL_SYSTEM_SHARED_LIBRARIES</h4> 936 <p>Used while building the base libraries: libc, libm, libdl. Usually 937 it should be set to "none," as it is in $(CLEAR_VARS). When building 938 these libraries, it's set to the ones they link against. For example, 939 libc, libstdc++ and libdl don't link against anything, and libm links against 940 libc. Normally, when the value is none, these libraries are automatically 941 linked in to executables and libraries, so you don't need to specify them 942 manually.</p> 943 944 945 </body> 946 </html> 947
