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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. 97This 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 113non-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 114want 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 118possible to easily rebuild just that component, and not have to wait more than a 119couple seconds for dependency checks, and not have to wait for unneeded 120components 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 123configuration file in a directory so they do not have an environment setup 124script to run, and others want an environment setup script to run so they can 125run builds in different terminals on the same tree, or switch back and forth 126in 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 129that 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 131this are to simplify searching the source tree, and to make "make clean" more 132reliable.</p> 133 134<h3>SDK</h3> 135<p>The SDK will be a tarball that will allow non-OS-developers to write apps. 136The apps will actually be built by first building the SDK, and then building 137the apps against that SDK. This will hopefully (1) make writing apps easier 138for us, because we won't have to rebuild the OS as much, and we can use the 139standard java-app development tools, and (2) allow us to dog-food the SDK, to 140help ensure its quality. Cedric has suggested (and I agree) that apps built 141from the SDK should be built with ant. Stay tuned for more details as we 142figure 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 148in 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 152executed for make steps. It will be possible to override this by specifying 153the showcommands pseudo-target, and possibly by setting an environment 154variable.</p> 155 156<h3>Wildcard source files</h3> 157<p>Wildcarding source file will be discouraged. It may be useful in some 158scenarios. The default <code>$(wildcard *)</code> will not work due to the 159current 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 163subdirectory. For example, libutils generates a shared library for the target 164and 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 168control the building of a given module. Only the top directory should 169have 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 173be fixed, and now is a good time to do it. This implies getting shared 174libraries 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, 180however 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 184tree at the same time, but this is a stretch goal, not a requirement. 185Doing two builds in the same tree, not at the same time must work. (update: 186it'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 191should 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 193problem is that this can create extra dependecies and slow down the build. 194It's a tradeoff.</p> 195 196<h3>Multiple builds</h3> 197<p>General way to perform builds across the set of known platforms. This 198would make it easy to perform multiple platform builds when testing a 199change, and allow a wide-scale "make clean". Right now the buildspec.mk 200or 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 204customizations 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, 209and 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 213builds.</p> 214 215<h3>build/envsetup.sh functions</h3> 216If 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 221lunch and choosecombo commands.</li> 222<li><b>m</b> - Runs <code>make</code> from the top of the tree. This is 223useful 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 225up 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, 228and .xml files below the current directory.</li> 229</ul> 230 231<h3>Build flavors/types</h3> 232<p> 233When building for a particular product, it's often useful to have minor 234variations on what is ultimately the final release build. These are the 235currently-defined "flavors" or "types" (we need to settle on a real name 236for 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>user</code>, and/or <code>development</code>. 251 <li>Installs non-APK modules that have no tags specified. 252 <li>Installs APKs according to the product definition files, in 253 addition to tagged APKs. 254 <li><code>ro.secure=0</code> 255 <li><code>ro.debuggable=1</code> 256 <li><code>ro.kernel.android.checkjni=1</code> 257 <li><code>adb</code> is enabled by default. 258 </td> 259</tr> 260<tr> 261 <td> 262 <code>user<code> 263 </td> 264 <td> 265 "<code>make user</code>" 266 <p> 267 This is the flavor intended to be the final release bits. 268 <ul> 269 <li>Installs modules tagged with <code>user</code>. 270 <li>Installs non-APK modules that have no tags specified. 271 <li>Installs APKs according to the product definition files; tags 272 are ignored for APK modules. 273 <li><code>ro.secure=1</code> 274 <li><code>ro.debuggable=0</code> 275 <li><code>adb</code> is disabled by default. 276 </td> 277</tr> 278<tr> 279 <td> 280 <code>userdebug<code> 281 </td> 282 <td> 283 "<code>make userdebug</code>" 284 <p> 285 The same as <code>user</code>, except: 286 <ul> 287 <li>Also installs modules tagged with <code>debug</code>. 288 <li><code>ro.debuggable=1</code> 289 <li><code>adb</code> is enabled by default. 290 </td> 291</tr> 292</table> 293 294<p> 295If you build one flavor and then want to build another, you should run 296"<code>make installclean</code>" between the two makes to guarantee that 297you don't pick up files installed by the previous flavor. "<code>make 298clean</code>" will also suffice, but it takes a lot longer. 299</p> 300 301 302<h3>More pseudotargets</h3> 303<p>Sometimes you want to just build one thing. The following pseudotargets are 304there for your convenience:</p> 305 306<ul> 307<li><b>droid</b> - <code>make droid</code> is the normal build. This target 308is here because the default target has to have a name.</li> 309<li><b>all</b> - <code>make all</code> builds everything <code>make 310droid</code> does, plus everything whose <code>LOCAL_MODULE_TAGS</code> do not 311include the "droid" tag. The build server runs this to make sure 312that everything that is in the tree and has an Android.mk builds.</li> 313<li><b>clean-$(LOCAL_MODULE)</b> and <b>clean-$(LOCAL_PACKAGE_NAME)</b> - 314Let you selectively clean one target. For example, you can type 315<code>make clean-libutils</code> and it will delete libutils.so and all of the 316intermediate files, or you can type <code>make clean-Home</code> and it will 317clean just the Home app.</li> 318<li><b>clean</b> - <code>make clean</code> deletes all of the output and 319intermediate files for this configuration. This is the same as <code>rm -rf 320out/<configuration>/</code></li> 321<li><b>clobber</b> - <code>make clobber</code> deletes all of the output 322and intermediate files for all configurations. This is the same as 323<code>rm -rf out/</code>.</li> 324<li><b>dataclean</b> - <code>make dataclean</code> deletes contents of the data 325directory inside the current combo directory. This is especially useful on the 326simulator and emulator, where the persistent data remains present between 327builds.</li> 328<li><b>showcommands</b> - <code>showcommands</code> is a modifier target 329which causes the build system to show the actual command lines for the build 330steps, instead of the brief descriptions. Most people don't like seeing the 331actual commands, because they're quite long and hard to read, but if you need 332to for debugging purposes, you can add <code>showcommands</code> to the list 333of targets you build. For example <code>make showcommands</code> will build 334the default android configuration, and <code>make runtime showcommands</code> 335will build just the runtime, and targets that it depends on, while displaying 336the full command lines. Please note that there are a couple places where the 337commands aren't shown here. These are considered bugs, and should be fixed, 338but they're often hard to track down. Please let 339<a href="mailto:android-build-team">android-build-team</a> know if you find 340any.</li> 341<li><b>LOCAL_MODULE</b> - Anything you specify as a <code>LOCAL_MODULE</code> 342in an Android.mk is made into a pseudotarget. For example, <code>make 343runtime</code> might be shorthand for <code>make 344out/linux-x86-debug/system/bin/runtime</code> (which would work), and 345<code>make libkjs</code> might be shorthand for <code>make 346out/linux-x86-debug/system/lib/libkjs.so</code> (which would also work).</li> 347<li><b>targets</b> - <code>make targets</code> will print a list of all of 348the LOCAL_MODULE names you can make.</li> 349</ul> 350 351<h3><a name="templates"/>How to add another component to the build - Android.mk templates</h3> 352<p>You have a new library, a new app, or a new executable. For each of the 353common types of modules, there is a corresponding file in the templates 354directory. It will usually be enough to copy one of these, and fill in your 355own values. Some of the more esoteric values are not included in the 356templates, but are instead just documented here, as is the documentation 357on using custom tools to generate files.</p> 358<p>Mostly, you can just look for the TODO comments in the templates and do 359what it says. Please remember to delete the TODO comments when you're done 360to keep the files clean. The templates have minimal documentation in them, 361because they're going to be copied, and when that gets stale, the copies just 362won't get updated. So read on...</p> 363 364<h4>Apps</h4> 365<p>Use the <code>templates/apps</code> file.</p> 366<p>This template is pretty self-explanitory. See the variables below for more 367details.</p> 368 369<h4>Java Libraries</h4> 370<p>Use the <code>templates/java_library</code> file.</p> 371<p>The interesting thing here is the value of LOCAL_MODULE, which becomes 372the name of the jar file. (Actually right now, we're not making jar files yet, 373just directories of .class files, but the directory is named according to 374what you put in LOCAL_MODULE). This name will be what goes in the 375LOCAL_JAVA_LIBRARIES variable in modules that depend on your java library.</p> 376 377<h4>C/C++ Executables</h4> 378<p>Use the <code>templates/executable</code> file, or the 379<code>templates/executable_host</code> file.</p> 380<p>This template has a couple extra options that you usually don't need. 381Please delete the ones you don't need, and remove the TODO comments. It makes 382the rest of them easier to read, and you can always refer back to the templates 383if you need them again later.</p> 384<p>By default, on the target these are built into /system/bin, and on the 385host, they're built into <combo>/host/bin. These can be overridden by setting 386<code>LOCAL_MODULE_PATH</code> or <code>LOCAL_MODULE_RELATIVE_PATH</code>. See 387<a href="#moving-targets">Putting targets elsewhere</a> 388for more.</p> 389 390<h4>Shared Libraries</h4> 391<p>Use the <code>templates/shared_library</code> file, or the 392<code>templates/shared_library_host</code> file.</p> 393<p>Remember that on the target, we use shared libraries, and on the host, 394we use static libraries, since executable size isn't as big an issue, and it 395simplifies distribution in the SDK.</p> 396 397<h4>Static Libraries</h4> 398<p>Use the <code>templates/static_library</code> file, or the 399<code>templates/static_library_host</code> file.</p> 400<p>Remember that on the target, we use shared libraries, and on the host, 401we use static libraries, since executable size isn't as big an issue, and it 402simplifies distribution in the SDK.</p> 403 404<h4><a name="custom-tools"/>Using Custom Tools</h4> 405<p>If you have a tool that generates source files for you, it's possible 406to have the build system get the dependencies correct for it. Here are 407a couple of examples. <code>$@</code> is the make built-in variable for 408"the current target." The <font color=red>red</font> parts are the parts you'll 409need to change.</p> 410 411<p>You need to put this after you have declared <code>LOCAL_PATH</code> and 412<code>LOCAL_MODULE</code>, because the <code>$(local-generated-sources-dir)</code> 413and <code>$(local-host-generated-sources-dir)</code> macros use these variables 414to determine where to put the files. 415 416<h5>Example 1</h5> 417<p>Here, there is one generated file, called 418chartables.c, which doesn't depend on anything. And is built by the tool 419built to $(HOST_OUT_EXECUTABLES)/dftables. Note on the second to last line 420that a dependency is created on the tool.</p> 421<pre> 422intermediates:= $(local-generated-sources-dir) 423GEN := $(intermediates)/<font color=red>chartables.c</font> 424$(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>$(HOST_OUT_EXECUTABLES)/dftables $@</font> 425$(GEN): <font color=red>$(HOST_OUT_EXECUTABLES)/dftables</font> 426 $(transform-generated-source) 427LOCAL_GENERATED_SOURCES += $(GEN) 428</pre> 429 430<h5>Example 2</h5> 431<p>Here as a hypothetical example, we use use cat as if it were to transform 432a file. Pretend that it does something useful. Note how we use a 433target-specific variable called PRIVATE_INPUT_FILE to store the name of the 434input file.</p> 435<pre> 436intermediates:= $(local-generated-sources-dir) 437GEN := $(intermediates)/<font color=red>file.c</font> 438$(GEN): PRIVATE_INPUT_FILE := $(LOCAL_PATH)/<font color=red>input.file</font> 439$(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>cat $(PRIVATE_INPUT_FILE) > $@</font> 440$(GEN): <font color=red>$(LOCAL_PATH)/file.c</font> 441 $(transform-generated-source) 442LOCAL_GENERATED_SOURCES += $(GEN) 443</pre> 444 445<h5>Example 3</h5> 446<p>If you have several files that are all similar in 447name, and use the same tool, you can combine them. (here the *.lut.h files are 448the generated ones, and the *.cpp files are the input files)</p> 449<pre> 450intermediates:= $(local-generated-sources-dir) 451GEN := $(addprefix $(intermediates)<font color=red>/kjs/, \ 452 array_object.lut.h \ 453 bool_object.lut.h \</font> 454 ) 455$(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>perl libs/WebKitLib/WebKit/JavaScriptCore/kjs/create_hash_table $< -i > $@</font> 456$(GEN): $(intermediates)/<font color=red>%.lut.h</font> : $(LOCAL_PATH)/<font color=red>%.cpp</font> 457 $(transform-generated-source) 458LOCAL_GENERATED_SOURCES += $(GEN) 459</pre> 460 461<h3><a name="platform-specific"/>Platform specific conditionals</h3> 462<p>Sometimes you need to set flags specifically for different platforms. Here 463is a list of which values the different build-system defined variables will be 464set to and some examples.</p> 465<p>For a device build, <code>TARGET_OS</code> is <code>linux</code> (we're using 466linux!), and <code>TARGET_ARCH</code> is <code>arm</code>.</p> 467<p>For a simulator build, <code>TARGET_OS</code> and <code>TARGET_ARCH</code> 468are set to the same as <code>HOST_OS</code> and <code>HOST_ARCH</code> are 469on your platform. <code>TARGET_PRODUCT</code> is the name of the target 470hardware/product you are building for. The value <code>sim</code> is used 471for the simulator. We haven't thought through the full extent of customization 472that will happen here, but likely there will be additional UI configurations 473specified here as well.</p> 474<table cellspacing=25> 475<tr> 476 <td valign=top align=center> 477 <b>HOST_OS</b><br/> 478 linux<br/> 479 darwin<br/> 480 (cygwin) 481 </td> 482 <td valign=top align=center> 483 <b>HOST_ARCH</b><br/> 484 x86 485 </td> 486 <td valign=top align=center> 487 <b>HOST_BUILD_TYPE</b><br/> 488 release<br/> 489 debug 490 </td> 491</tr> 492<tr> 493 <td valign=top align=center> 494 <b>TARGET_OS</b><br/> 495 linux<br/> 496 darwin<br/> 497 (cygwin) 498 </td> 499 <td valign=top align=center> 500 <b>TARGET_ARCH</b><br/> 501 arm<br/> 502 x86 503 </td> 504 <td valign=top align=center> 505 <b>TARGET_BUILD_TYPE</b><br/> 506 release<br/> 507 debug 508 </td> 509 <td valign=top align=center> 510 <b>TARGET_PRODUCT</b><br/> 511 sim<br/> 512 dream<br/> 513 sooner 514 </td> 515</tr> 516</table> 517 518<h4>Some Examples</h4> 519<pre>ifeq ($(TARGET_BUILD_TYPE),release) 520LOCAL_CFLAGS += -DNDEBUG=1 521endif 522 523# from libutils 524ifeq ($(TARGET_OS),linux) 525# Use the futex based mutex and condition variable 526# implementation from android-arm because it's shared mem safe 527LOCAL_SRC_FILES += futex_synchro.c 528LOCAL_LDLIBS += -lrt -ldl 529endif 530 531</pre> 532 533 534<h3><a name="moving-modules"/>Putting modules elsewhere</h3> 535<p>If you have modules that normally go somewhere, and you need to have them 536build somewhere else, read this.</p> 537<p>If you have modules that need to go in a subdirectory of their normal 538location, for example HAL modules that need to go in /system/lib/hw or 539/vendor/lib/hw, set LOCAL_MODULE_RELATIVE_PATH in your Android.mk, for 540example:</p> 541<pre> 542LOCAL_MODULE_RELATIVE_PATH := hw 543</pre> 544<p>If you have modules that need to go in an entirely different location, for 545example the root filesystem instead of in /system, add these lines to your 546Android.mk:</p> 547<pre> 548LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN) 549LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED) 550</pre> 551<p>For executables and libraries, you need to specify a 552<code>LOCAL_UNSTRIPPED_PATH</code> location if you specified a 553<code>LOCAL_MODULE_PATH</code>, because on target builds, we keep 554the unstripped executables so GDB can find the symbols. 555<code>LOCAL_UNSTRIPPED_PATH</code> is not necessary if you only specified 556<code>LOCAL_MODULE_RELATIVE_PATH</code>.</p> 557<p>Look in <code>config/envsetup.make</code> for all of the variables defining 558places to build things.</p> 559<p>FYI: If you're installing an executable to /sbin, you probably also want to 560set <code>LOCAL_FORCE_STATIC_EXCUTABLE := true</code> in your Android.mk, which 561will force the linker to only accept static libraries.</p> 562 563 564<h3>Android.mk variables</h3> 565<p>These are the variables that you'll commonly see in Android.mk files, listed 566alphabetically.</p> 567<p>But first, a note on variable naming: 568<ul> 569 <li><b>LOCAL_</b> - These variables are set per-module. They are cleared 570 by the <code>include $(CLEAR_VARS)</code> line, so you can rely on them 571 being empty after including that file. Most of the variables you'll use 572 in most modules are LOCAL_ variables.</li> 573 <li><b>PRIVATE_</b> - These variables are make-target-specific variables. That 574 means they're only usable within the commands for that module. It also 575 means that they're unlikely to change behind your back from modules that 576 are included after yours. This 577 <a href="http://www.gnu.org/software/make/manual/make.html#Target_002dspecific">link to the make documentation</a> 578 describes more about target-specific variables. Please note that there 579 are a couple of these laying around the tree that aren't prefixed with 580 PRIVATE_. It is safe, and they will be fixed as they are discovered. 581 Sorry for the confusion.</li> 582 <li><b>INTERNAL_</b> - These variables are critical to functioning of 583 the build system, so you shouldn't create variables named like this, and 584 you probably shouldn't be messing with these variables in your makefiles. 585 </li> 586 <li><b>HOST_</b> and <b>TARGET_</b> - These contain the directories 587 and definitions that are specific to either the host or the target builds. 588 Do not set variables that start with HOST_ or TARGET_ in your makefiles. 589 </li> 590 <li><b>BUILD_</b> and <b>CLEAR_VARS</b> - These contain the names of 591 well-defined template makefiles to include. Some examples are CLEAR_VARS 592 and BUILD_HOST_PACKAGE.</li> 593 <li>Any other name is fair-game for you to use in your Android.mk. However, 594 remember that this is a non-recursive build system, so it is possible that 595 your variable will be changed by another Android.mk included later, and be 596 different when the commands for your rule / module are executed.</li> 597</ul> 598</p> 599 600<h4>LOCAL_ASSET_FILES</h4> 601<p>In Android.mk files that <code>include $(BUILD_PACKAGE)</code> set this 602to the set of files you want built into your app. Usually:</p> 603<p><code>LOCAL_ASSET_FILES += $(call find-subdir-assets)</code></p> 604<p>This will probably change when we switch to ant for the apps' build 605system.</p> 606 607<h4>LOCAL_CC</h4> 608<p>If you want to use a different C compiler for this module, set LOCAL_CC 609to the path to the compiler. If LOCAL_CC is blank, the appropriate default 610compiler is used.</p> 611 612<h4>LOCAL_CXX</h4> 613<p>If you want to use a different C++ compiler for this module, set LOCAL_CXX 614to the path to the compiler. If LOCAL_CXX is blank, the appropriate default 615compiler is used.</p> 616 617<h4>LOCAL_CFLAGS</h4> 618<p>If you have additional flags to pass into the C or C++ compiler, add 619them here. For example:</p> 620<p><code>LOCAL_CFLAGS += -DLIBUTILS_NATIVE=1</code></p> 621 622<h4>LOCAL_CPPFLAGS</h4> 623<p>If you have additional flags to pass into <i>only</i> the C++ compiler, add 624them here. For example:</p> 625<p><code>LOCAL_CPPFLAGS += -ffriend-injection</code></p> 626<code>LOCAL_CPPFLAGS</code> is guaranteed to be after <code>LOCAL_CFLAGS</code> 627on the compile line, so you can use it to override flags listed in 628<code>LOCAL_CFLAGS</code>. 629 630<h4>LOCAL_CPP_EXTENSION</h4> 631<p>If your C++ files end in something other than "<code>.cpp</code>", 632you can specify the custom extension here. For example:</p> 633<p><code>LOCAL_CPP_EXTENSION := .cc</code></p> 634Note that all C++ files for a given module must have the same 635extension; it is not currently possible to mix different extensions. 636 637<h4>LOCAL_NO_DEFAULT_COMPILER_FLAGS</h4> 638<p>Normally, the compile line for C and C++ files includes global include 639paths and global cflags. If <code>LOCAL_NO_DEFAULT_COMPILER_FLAGS</code> 640is non-empty, none of the default includes or flags will be used when compiling 641C and C++ files in this module. 642<code>LOCAL_C_INCLUDES</code>, <code>LOCAL_CFLAGS</code>, and 643<code>LOCAL_CPPFLAGS</code> will still be used in this case, as will 644any <code>DEBUG_CFLAGS</code> that are defined for the module. 645 646<h4>LOCAL_COPY_HEADERS</h4> 647<p class=warning>This will be going away.</p> 648<p>The set of files to copy to the install include tree. You must also 649supply <code>LOCAL_COPY_HEADERS_TO</code>.</p> 650<p>This is going away because copying headers messes up the error messages, and 651may lead to people editing those headers instead of the correct ones. It also 652makes it easier to do bad layering in the system, which we want to avoid. We 653also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any 654headers.</p> 655 656<h4>LOCAL_COPY_HEADERS_TO</h4> 657<p class=warning>This will be going away.</p> 658<p>The directory within "include" to copy the headers listed in 659<code>LOCAL_COPY_HEADERS</code> to.</p> 660<p>This is going away because copying headers messes up the error messages, and 661may lead to people editing those headers instead of the correct ones. It also 662makes it easier to do bad layering in the system, which we want to avoid. We 663also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any 664headers.</p> 665 666<h4>LOCAL_C_INCLUDES</h4> 667<p>Additional directories to instruct the C/C++ compilers to look for header 668files in. These paths are rooted at the top of the tree. Use 669<code>LOCAL_PATH</code> if you have subdirectories of your own that you 670want in the include paths. For example:</p> 671<p><code> 672LOCAL_C_INCLUDES += extlibs/zlib-1.2.3<br/> 673LOCAL_C_INCLUDES += $(LOCAL_PATH)/src 674</code></p> 675<p>You should not add subdirectories of include to 676<code>LOCAL_C_INCLUDES</code>, instead you should reference those files 677in the <code>#include</code> statement with their subdirectories. For 678example:</p> 679<p><code>#include <utils/KeyedVector.h></code><br/> 680not <code><s>#include <KeyedVector.h></s></code></p> 681<p>There are some components that are doing this wrong, and should be cleaned 682up.</p> 683 684<h4>LOCAL_MODULE_TAGS</h4> 685<p>Set <code>LOCAL_MODULE_TAGS</code> to any number of whitespace-separated 686tags. If the tag list is empty or contains <code>droid</code>, the module 687will get installed as part of a <code>make droid</code>. Otherwise, it will 688only get installed by running <code>make <your-module></code> 689or with the <code>make all</code> pseudotarget.</p> 690 691<h4>LOCAL_REQUIRED_MODULES</h4> 692<p>Set <code>LOCAL_REQUIRED_MODULES</code> to any number of whitespace-separated 693module names, like "libblah" or "Email". If this module is installed, all 694of the modules that it requires will be installed as well. This can be 695used to, e.g., ensure that necessary shared libraries or providers are 696installed when a given app is installed. 697 698<h4>LOCAL_FORCE_STATIC_EXECUTABLE</h4> 699<p>If your executable should be linked statically, set 700<code>LOCAL_FORCE_STATIC_EXECUTABLE:=true</code>. There is a very short 701list of libraries that we have in static form (currently only libc). This is 702really only used for executables in /sbin on the root filesystem.</p> 703 704<h4>LOCAL_GENERATED_SOURCES</h4> 705<p>Files that you add to <code>LOCAL_GENERATED_SOURCES</code> will be 706automatically generated and then linked in when your module is built. 707See the <a href="#custom-tools">Custom Tools</a> template makefile for an 708example.</p> 709 710<h4>LOCAL_JAVACFLAGS</h4> 711<p>If you have additional flags to pass into the javac compiler, add 712them here. For example:</p> 713<p><code>LOCAL_JAVACFLAGS += -Xlint:deprecation</code></p> 714 715<h4>LOCAL_JAVA_LIBRARIES</h4> 716<p>When linking Java apps and libraries, <code>LOCAL_JAVA_LIBRARIES</code> 717specifies which sets of java classes to include. Currently there are 718two of these: <code>core</code> and <code>framework</code>. 719In most cases, it will look like this:</p> 720<p><code>LOCAL_JAVA_LIBRARIES := core framework</code></p> 721<p>Note that setting <code>LOCAL_JAVA_LIBRARIES</code> is not necessary 722(and is not allowed) when building an APK with 723"<code>include $(BUILD_PACKAGE)</code>". The appropriate libraries 724will be included automatically.</p> 725 726<h4>LOCAL_LDFLAGS</h4> 727<p>You can pass additional flags to the linker by setting 728<code>LOCAL_LDFLAGS</code>. Keep in mind that the order of parameters is 729very important to ld, so test whatever you do on all platforms.</p> 730 731<h4>LOCAL_LDLIBS</h4> 732<p><code>LOCAL_LDLIBS</code> allows you to specify additional libraries 733that are not part of the build for your executable or library. Specify 734the libraries you want in -lxxx format; they're passed directly to the 735link line. However, keep in mind that there will be no dependency generated 736for these libraries. It's most useful in simulator builds where you want 737to use a library preinstalled on the host. The linker (ld) is a particularly 738fussy beast, so it's sometimes necessary to pass other flags here if you're 739doing something sneaky. Some examples:</p> 740<p><code>LOCAL_LDLIBS += -lcurses -lpthread<br/> 741LOCAL_LDLIBS += -Wl,-z,origin 742</code></p> 743 744<h4>LOCAL_NO_MANIFEST</h4> 745<p>If your package doesn't have a manifest (AndroidManifest.xml), then 746set <code>LOCAL_NO_MANIFEST:=true</code>. The common resources package 747does this.</p> 748 749<h4>LOCAL_PACKAGE_NAME</h4> 750<p><code>LOCAL_PACKAGE_NAME</code> is the name of an app. For example, 751Dialer, Contacts, etc. This will probably change or go away when we switch 752to an ant-based build system for the apps.</p> 753 754<h4>LOCAL_PATH</h4> 755<p>The directory your Android.mk file is in. You can set it by putting the 756following as the first line in your Android.mk:</p> 757<p><code>LOCAL_PATH := $(my-dir)</code></p> 758<p>The <code>my-dir</code> macro uses the 759<code><a href="http://www.gnu.org/software/make/manual/make.html#MAKEFILE_005fLIST-Variable">MAKEFILE_LIST</a></code> 760variable, so you must call it before you include any other makefiles. Also, 761consider that any subdirectories you inlcude might reset LOCAL_PATH, so do your 762own stuff before you include them. This also means that if you try to write 763several <code>include</code> lines that reference <code>LOCAL_PATH</code>, 764it won't work, because those included makefiles might reset LOCAL_PATH. 765 766<h4>LOCAL_POST_PROCESS_COMMAND</h4> 767<p>For host executables, you can specify a command to run on the module 768after it's been linked. You might have to go through some contortions 769to get variables right because of early or late variable evaluation:</p> 770<p><code>module := $(HOST_OUT_EXECUTABLES)/$(LOCAL_MODULE)<br/> 771LOCAL_POST_PROCESS_COMMAND := /Developer/Tools/Rez -d __DARWIN__ -t APPL\<br/> 772 -d __WXMAC__ -o $(module) Carbon.r 773</code></p> 774 775<h4>LOCAL_PREBUILT_EXECUTABLES</h4> 776<p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to 777executables that you want copied. They're located automatically into the 778right bin directory.</p> 779 780<h4>LOCAL_PREBUILT_LIBS</h4> 781<p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to 782libraries that you want copied. They're located automatically into the 783right lib directory.</p> 784 785<h4>LOCAL_SHARED_LIBRARIES</h4> 786<p>These are the libraries you directly link against. You don't need to 787pass transitively included libraries. Specify the name without the suffix:</p> 788<p><code>LOCAL_SHARED_LIBRARIES := \<br/> 789 libutils \<br/> 790 libui \<br/> 791 libaudio \<br/> 792 libexpat \<br/> 793 libsgl 794</code></p> 795 796<h4>LOCAL_SRC_FILES</h4> 797<p>The build system looks at <code>LOCAL_SRC_FILES</code> to know what source 798files to compile -- .cpp .c .y .l .java. For lex and yacc files, it knows 799how to correctly do the intermediate .h and .c/.cpp files automatically. If 800the files are in a subdirectory of the one containing the Android.mk, prefix 801them with the directory name:</p> 802<p><code>LOCAL_SRC_FILES := \<br/> 803 file1.cpp \<br/> 804 dir/file2.cpp 805</code></p> 806 807<h4>LOCAL_STATIC_LIBRARIES</h4> 808<p>These are the static libraries that you want to include in your module. 809Mostly, we use shared libraries, but there are a couple of places, like 810executables in sbin and host executables where we use static libraries instead. 811<p><code>LOCAL_STATIC_LIBRARIES := \<br/> 812 libutils \<br/> 813 libtinyxml 814</code></p> 815 816<h4>LOCAL_MODULE</h4> 817<p><code>LOCAL_MODULE</code> is the name of what's supposed to be generated 818from your Android.mk. For exmample, for libkjs, the <code>LOCAL_MODULE</code> 819is "libkjs" (the build system adds the appropriate suffix -- .so .dylib .dll). 820For app modules, use <code>LOCAL_PACKAGE_NAME</code> instead of 821<code>LOCAL_MODULE</code>. We're planning on switching to ant for the apps, 822so this might become moot.</p> 823 824<h4>LOCAL_MODULE_PATH</h4> 825<p>Instructs the build system to put the module somewhere other than what's 826normal for its type. If you override this, make sure you also set 827<code>LOCAL_UNSTRIPPED_PATH</code> if it's an executable or a shared library 828so the unstripped binary has somewhere to go. An error will occur if you forget 829to.</p> 830<p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p> 831 832<h4>LOCAL_MODULE_RELATIVE_PATH</h4> 833<p>Instructs the build system to put the module in a subdirectory under the 834directory that is normal for its type. If you set this you do not need to 835set <code>LOCAL_UNSTRIPPED_PATH</code>, the unstripped binaries will also use 836the relative path.</p> 837<p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p> 838 839<h4>LOCAL_UNSTRIPPED_PATH</h4> 840<p>Instructs the build system to put the unstripped version of the module 841somewhere other than what's normal for its type. Usually, you override this 842because you overrode <code>LOCAL_MODULE_PATH</code> for an executable or a 843shared library. If you overrode <code>LOCAL_MODULE_PATH</code>, but not 844<code>LOCAL_UNSTRIPPED_PATH</code>, an error will occur.</p> 845<p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p> 846 847<h4>LOCAL_WHOLE_STATIC_LIBRARIES</h4> 848<p>These are the static libraries that you want to include in your module without allowing 849the linker to remove dead code from them. This is mostly useful if you want to add a static library 850to a shared library and have the static library's content exposed from the shared library. 851<p><code>LOCAL_WHOLE_STATIC_LIBRARIES := \<br/> 852 libsqlite3_android<br/> 853</code></p> 854 855<h4>LOCAL_YACCFLAGS</h4> 856<p>Any flags to pass to invocations of yacc for your module. A known limitation 857here is that the flags will be the same for all invocations of YACC for your 858module. This can be fixed. If you ever need it to be, just ask.</p> 859<p><code>LOCAL_YACCFLAGS := -p kjsyy</code></p> 860 861 862 863<h2>Implementation Details</h2> 864 865<p>You should never have to touch anything in the config directory unless 866you're adding a new platform, new tools, or adding new features to the 867build system. In general, please consult with the build system owner(s) 868(<a href="mailto:android-build-team">android-build-team</a>) before you go 869mucking around in here. That said, here are some notes on what's going on 870under the hood.</p> 871 872<h3>Environment Setup / buildspec.mk Versioning</h3> 873<p>In order to make easier for people when the build system changes, when 874it is necessary to make changes to buildspec.mk or to rerun the environment 875setup scripts, they contain a version number in the variable 876BUILD_ENV_SEQUENCE_NUMBER. If this variable does not match what the build 877system expects, it fails printing an error message explaining what happened. 878If you make a change that requires an update, you need to update two places 879so this message will be printed. 880<ul> 881 <li>In config/envsetup.make, increment the 882 CORRECT_BUILD_ENV_SEQUENCE_NUMBER definition.</li> 883 <li>In buildspec.mk.default, update the BUILD_ENV_SEQUENCE_DUMBER 884 definition to match the one in config/envsetup.make</li> 885</ul> 886The scripts automatically get the value from the build system, so they will 887trigger the warning as well. 888</p> 889 890<h3>Additional makefile variables</h3> 891<p>You probably shouldn't use these variables. Please consult 892<a href="mailto:android-build-team">android-build-team</a> before using them. 893These are mostly there for workarounds for other issues, or things that aren't 894completely done right.</p> 895 896<h4>LOCAL_ADDITIONAL_DEPENDENCIES</h4> 897<p>If your module needs to depend on anything else that 898isn't actually built in to it, you can add those make targets to 899<code>LOCAL_ADDITIONAL_DEPENDENCIES</code>. Usually this is a workaround 900for some other dependency that isn't created automatically.</p> 901 902<h4>LOCAL_BUILT_MODULE</h4> 903<p>When a module is built, the module is created in an intermediate 904directory then copied to its final location. LOCAL_BUILT_MODULE is 905the full path to the intermediate file. See LOCAL_INSTALLED_MODULE 906for the path to the final installed location of the module.</p> 907 908<h4>LOCAL_HOST</h4> 909<p>Set by the host_xxx.make includes to tell base_rules.make and the other 910includes that we're building for the host. Kenneth did this as part of 911openbinder, and I would like to clean it up so the rules, includes and 912definitions aren't duplicated for host and target.</p> 913 914<h4>LOCAL_INSTALLED_MODULE</h4> 915<p>The fully qualified path name of the final location of the module. 916See LOCAL_BUILT_MODULE for the location of the intermediate file that 917the make rules should actually be constructing.</p> 918 919<h4>LOCAL_REPLACE_VARS</h4> 920<p>Used in some stuff remaining from the openbinder for building scripts 921with particular values set,</p> 922 923<h4>LOCAL_SCRIPTS</h4> 924<p>Used in some stuff remaining from the openbinder build system that we 925might find handy some day.</p> 926 927<h4>LOCAL_MODULE_CLASS</h4> 928<p>Which kind of module this is. This variable is used to construct other 929variable names used to locate the modules. See base_rules.make and 930envsetup.make.</p> 931 932<h4>LOCAL_MODULE_NAME</h4> 933<p>Set to the leaf name of the LOCAL_BUILT_MODULE. I'm not sure, 934but it looks like it's just used in the WHO_AM_I variable to identify 935in the pretty printing what's being built.</p> 936 937<h4>LOCAL_MODULE_SUFFIX</h4> 938<p>The suffix that will be appended to <code>LOCAL_MODULE</code> to form 939<code>LOCAL_MODULE_NAME</code>. For example, .so, .a, .dylib.</p> 940 941<h4>LOCAL_STRIP_MODULE</h4> 942<p>Calculated in base_rules.make to determine if this module should actually 943be stripped or not, based on whether <code>LOCAL_STRIPPABLE_MODULE</code> 944is set, and whether the combo is configured to ever strip modules. With 945Iliyan's stripping tool, this might change.</p> 946 947<h4>LOCAL_STRIPPABLE_MODULE</h4> 948<p>Set by the include makefiles if that type of module is strippable. 949Executables and shared libraries are.</p> 950 951<h4>LOCAL_SYSTEM_SHARED_LIBRARIES</h4> 952<p>Used while building the base libraries: libc, libm, libdl. Usually 953it should be set to "none," as it is in $(CLEAR_VARS). When building 954these libraries, it's set to the ones they link against. For example, 955libc, libstdc++ and libdl don't link against anything, and libm links against 956libc. Normally, when the value is none, these libraries are automatically 957linked in to executables and libraries, so you don't need to specify them 958manually.</p> 959 960 961</body> 962</html> 963