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72<h1><a name="My_Project_" />Android Build System</h1>
73
74<!-- Status is one of: Draft, Current, Needs Update, Obsolete -->
75<p style="text-align:center">
76 <strong>Status:</strong> <em>Draft </em> &nbsp;
77 <small>(as of May 18, 2006)</small>
78</p>
79
80<p><b>Contents</b></p>
81<!-- this div expands out to a list of contents based on the H2 and H3 headings.
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83 <div id="nav" class="nav-2-levels"></div>
84
85<h2>Objective</h2>
86<p>The primary goals of reworking the build system are (1) to make dependencies
87work more reliably, so that when files need to rebuilt, they are, and (2) to
88improve performance of the build system so that unnecessary modules are not
89rebuilt, and so doing a top-level build when little or nothing needs to be done
90for a build takes as little time as possible.</p>
91
92<h2>Principles and Use Cases and Policy</h2>
93<p>Given the above objective, these are the overall principles and use cases
94that we will support. 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>,
Thorsten Glaser2213aab2010-06-03 19:57:02 +0200250 <code>shell_</code>$(TARGET_SHELL),
Joe Onorato2303bf02008-10-23 19:37:58 -0700251 <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>
Thorsten Glaser2213aab2010-06-03 19:57:02 +0200270 <li>Installs modules tagged with <code>shell_</code>$(TARGET_SHELL) and <code>user</code>.
Joe Onorato2303bf02008-10-23 19:37:58 -0700271 <li>Installs non-APK modules that have no tags specified.
272 <li>Installs APKs according to the product definition files; tags
273 are ignored for APK modules.
274 <li><code>ro.secure=1</code>
275 <li><code>ro.debuggable=0</code>
276 <li><code>adb</code> is disabled by default.
277 </td>
278</tr>
279<tr>
280 <td>
281 <code>userdebug<code>
282 </td>
283 <td>
284 "<code>make userdebug</code>"
285 <p>
286 The same as <code>user</code>, except:
287 <ul>
288 <li>Also installs modules tagged with <code>debug</code>.
289 <li><code>ro.debuggable=1</code>
290 <li><code>adb</code> is enabled by default.
291 </td>
292</tr>
293</table>
294
295<p>
296If you build one flavor and then want to build another, you should run
297"<code>make installclean</code>" between the two makes to guarantee that
298you don't pick up files installed by the previous flavor. "<code>make
299clean</code>" will also suffice, but it takes a lot longer.
300</p>
301
302
303<h3>More pseudotargets</h3>
304<p>Sometimes you want to just build one thing. The following pseudotargets are
305there for your convenience:</p>
306
307<ul>
308<li><b>droid</b> - <code>make droid</code> is the normal build. This target
309is here because the default target has to have a name.</li>
310<li><b>all</b> - <code>make all</code> builds everything <code>make
311droid</code> does, plus everything whose <code>LOCAL_MODULE_TAGS</code> do not
312include the "droid" tag. The build server runs this to make sure
313that everything that is in the tree and has an Android.mk builds.</li>
314<li><b>clean-$(LOCAL_MODULE)</b> and <b>clean-$(LOCAL_PACKAGE_NAME)</b> -
315Let 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
317intermediate files, or you can type <code>make clean-Home</code> and it will
318clean just the Home app.</li>
319<li><b>clean</b> - <code>make clean</code> deletes all of the output and
320intermediate files for this configuration. This is the same as <code>rm -rf
321out/&lt;configuration&gt;/</code></li>
322<li><b>clobber</b> - <code>make clobber</code> deletes all of the output
323and 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
326directory inside the current combo directory. This is especially useful on the
327simulator and emulator, where the persistent data remains present between
328builds.</li>
329<li><b>showcommands</b> - <code>showcommands</code> is a modifier target
330which causes the build system to show the actual command lines for the build
331steps, instead of the brief descriptions. Most people don't like seeing the
332actual commands, because they're quite long and hard to read, but if you need
333to for debugging purposes, you can add <code>showcommands</code> to the list
334of targets you build. For example <code>make showcommands</code> will build
335the default android configuration, and <code>make runtime showcommands</code>
336will build just the runtime, and targets that it depends on, while displaying
337the full command lines. Please note that there are a couple places where the
338commands aren't shown here. These are considered bugs, and should be fixed,
339but they're often hard to track down. Please let
340<a href="mailto:android-build-team">android-build-team</a> know if you find
341any.</li>
342<li><b>LOCAL_MODULE</b> - Anything you specify as a <code>LOCAL_MODULE</code>
343in an Android.mk is made into a pseudotarget. For example, <code>make
344runtime</code> might be shorthand for <code>make
345out/linux-x86-debug/system/bin/runtime</code> (which would work), and
346<code>make libkjs</code> might be shorthand for <code>make
347out/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
349the 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
354common types of modules, there is a corresponding file in the templates
355directory. It will usually be enough to copy one of these, and fill in your
356own values. Some of the more esoteric values are not included in the
357templates, but are instead just documented here, as is the documentation
358on using custom tools to generate files.</p>
359<p>Mostly, you can just look for the TODO comments in the templates and do
360what it says. Please remember to delete the TODO comments when you're done
361to keep the files clean. The templates have minimal documentation in them,
362because they're going to be copied, and when that gets stale, the copies just
363won'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
368details.</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
373the name of the jar file. (Actually right now, we're not making jar files yet,
374just directories of .class files, but the directory is named according to
375what you put in LOCAL_MODULE). This name will be what goes in the
376LOCAL_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.
382Please delete the ones you don't need, and remove the TODO comments. It makes
383the rest of them easier to read, and you can always refer back to the templates
384if you need them again later.</p>
385<p>By default, on the target these are built into /system/bin, and on the
386host, 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>
389for 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,
395we use static libraries, since executable size isn't as big an issue, and it
396simplifies 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,
402we use static libraries, since executable size isn't as big an issue, and it
403simplifies 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
407to have the build system get the dependencies correct for it. Here are
408a 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
410need 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>$(local-intermediates-dir)</code>
414and <code>$(local-host-intermediates-dir)</code> macros use these variables
415to determine where to put the files.
416
417<h5>Example 1</h5>
418<p>Here, there is one generated file, called
419chartables.c, which doesn't depend on anything. And is built by the tool
420built to $(HOST_OUT_EXECUTABLES)/dftables. Note on the second to last line
421that a dependency is created on the tool.</p>
422<pre>
423intermediates:= $(local-intermediates-dir)
424GEN := $(intermediates)/<font color=red>chartables.c</font>
425$(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)
428LOCAL_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
433a file. Pretend that it does something useful. Note how we use a
434target-specific variable called PRIVATE_INPUT_FILE to store the name of the
435input file.</p>
436<pre>
437intermediates:= $(local-intermediates-dir)
438GEN := $(intermediates)/<font color=red>file.c</font>
439$(GEN): PRIVATE_INPUT_FILE := $(LOCAL_PATH)/<font color=red>input.file</font>
440$(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>cat $(PRIVATE_INPUT_FILE) &gt; $@</font>
441$(GEN): <font color=red>$(LOCAL_PATH)/file.c</font>
442 $(transform-generated-source)
443LOCAL_GENERATED_SOURCES += $(GEN)
444</pre>
445
446<h5>Example 3</h5>
447<p>If you have several files that are all similar in
448name, and use the same tool, you can combine them. (here the *.lut.h files are
449the generated ones, and the *.cpp files are the input files)</p>
450<pre>
451intermediates:= $(local-intermediates-dir)
452GEN := $(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)
459LOCAL_GENERATED_SOURCES += $(GEN)
460</pre>
461
462<h3><a name="platform-specific"/>Platform specific conditionals</h3>
463<p>Sometimes you need to set flags specifically for different platforms. Here
464is a list of which values the different build-system defined variables will be
465set to and some examples.</p>
466<p>For a device build, <code>TARGET_OS</code> is <code>linux</code> (we're using
467linux!), and <code>TARGET_ARCH</code> is <code>arm</code>.</p>
468<p>For a simulator build, <code>TARGET_OS</code> and <code>TARGET_ARCH</code>
469are set to the same as <code>HOST_OS</code> and <code>HOST_ARCH</code> are
470on your platform. <code>TARGET_PRODUCT</code> is the name of the target
471hardware/product you are building for. The value <code>sim</code> is used
472for the simulator. We haven't thought through the full extent of customization
473that will happen here, but likely there will be additional UI configurations
474specified here as well.</p>
475<table cellspacing=25>
476<tr>
477 <td valign=top align=center>
478 <b>HOST_OS</b><br/>
479 linux<br/>
480 darwin<br/>
481 (cygwin)
482 </td>
483 <td valign=top align=center>
484 <b>HOST_ARCH</b><br/>
485 x86
486 </td>
487 <td valign=top align=center>
488 <b>HOST_BUILD_TYPE</b><br/>
489 release<br/>
490 debug
491 </td>
492</tr>
493<tr>
494 <td valign=top align=center>
495 <b>TARGET_OS</b><br/>
496 linux<br/>
497 darwin<br/>
498 (cygwin)
499 </td>
500 <td valign=top align=center>
501 <b>TARGET_ARCH</b><br/>
502 arm<br/>
503 x86
504 </td>
505 <td valign=top align=center>
506 <b>TARGET_BUILD_TYPE</b><br/>
507 release<br/>
508 debug
509 </td>
510 <td valign=top align=center>
511 <b>TARGET_PRODUCT</b><br/>
512 sim<br/>
513 dream<br/>
514 sooner
515 </td>
516</tr>
517</table>
518
Joe Onorato2303bf02008-10-23 19:37:58 -0700519<h4>Some Examples</h4>
Jeff Browne33ba4c2011-07-11 22:11:46 -0700520<pre>ifeq ($(TARGET_BUILD_TYPE),release)
Joe Onorato2303bf02008-10-23 19:37:58 -0700521LOCAL_CFLAGS += -DNDEBUG=1
522endif
523
524# from libutils
525ifeq ($(TARGET_OS),linux)
526# Use the futex based mutex and condition variable
527# implementation from android-arm because it's shared mem safe
528LOCAL_SRC_FILES += futex_synchro.c
529LOCAL_LDLIBS += -lrt -ldl
530endif
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
537build somewhere else, read this. One use of this is putting files on
538the root filesystem instead of where they normally go in /system. Add these
539lines to your Android.mk:</p>
540<pre>
541LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN)
542LOCAL_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
546the unstripped executables so GDB can find the symbols.</code>
547<p>Look in <code>config/envsetup.make</code> for all of the variables defining
548places to build things.</p>
549<p>FYI: If you're installing an executable to /sbin, you probably also want to
550set <code>LOCAL_FORCE_STATIC_EXCUTABLE := true</code> in your Android.mk, which
551will 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
556alphabetically.</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
592to 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
595system.</p>
596
597<h4>LOCAL_CC</h4>
598<p>If you want to use a different C compiler for this module, set LOCAL_CC
599to the path to the compiler. If LOCAL_CC is blank, the appropriate default
600compiler 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
604to the path to the compiler. If LOCAL_CXX is blank, the appropriate default
605compiler 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
609them 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
614them 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>
617on 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>",
622you can specify the custom extension here. For example:</p>
623<p><code>LOCAL_CPP_EXTENSION := .cc</code></p>
624Note that all C++ files for a given module must have the same
625extension; 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
629paths and global cflags. If <code>LOCAL_NO_DEFAULT_COMPILER_FLAGS</code>
630is non-empty, none of the default includes or flags will be used when compiling
631C 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
634any <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
639supply <code>LOCAL_COPY_HEADERS_TO</code>.</p>
640<p>This is going away because copying headers messes up the error messages, and
641may lead to people editing those headers instead of the correct ones. It also
642makes it easier to do bad layering in the system, which we want to avoid. We
643also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any
644headers.</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
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_C_INCLUDES</h4>
657<p>Additional directories to instruct the C/C++ compilers to look for header
658files 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
660want in the include paths. For example:</p>
661<p><code>
662LOCAL_C_INCLUDES += extlibs/zlib-1.2.3<br/>
663LOCAL_C_INCLUDES += $(LOCAL_PATH)/src
664</code></p>
665<p>You should not add subdirectories of include to
666<code>LOCAL_C_INCLUDES</code>, instead you should reference those files
667in the <code>#include</code> statement with their subdirectories. For
668example:</p>
669<p><code>#include &lt;utils/KeyedVector.h&gt;</code><br/>
670not <code><s>#include &lt;KeyedVector.h&gt;</s></code></p>
671<p>There are some components that are doing this wrong, and should be cleaned
672up.</p>
673
674<h4>LOCAL_MODULE_TAGS</h4>
675<p>Set <code>LOCAL_MODULE_TAGS</code> to any number of whitespace-separated
676tags. If the tag list is empty or contains <code>droid</code>, the module
Thorsten Glaser2213aab2010-06-03 19:57:02 +0200677will get installed as part of a <code>make droid</code>. Modules with the tag
678<code>shell_</code>$(TARGET_SHELL) will also be installed. Otherwise, it will
Joe Onorato2303bf02008-10-23 19:37:58 -0700679only get installed by running <code>make &lt;your-module&gt;</code>
680or 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
684module names, like "libblah" or "Email". If this module is installed, all
685of the modules that it requires will be installed as well. This can be
686used to, e.g., ensure that necessary shared libraries or providers are
687installed 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
692list of libraries that we have in static form (currently only libc). This is
693really 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
697automatically generated and then linked in when your module is built.
698See the <a href="#custom-tools">Custom Tools</a> template makefile for an
699example.</p>
700
Brian Carlstromf184a0f2010-02-01 11:13:32 -0800701<h4>LOCAL_JAVACFLAGS</h4>
702<p>If you have additional flags to pass into the javac compiler, add
703them here. For example:</p>
704<p><code>LOCAL_JAVACFLAGS += -Xlint:deprecation</code></p>
705
Joe Onorato2303bf02008-10-23 19:37:58 -0700706<h4>LOCAL_JAVA_LIBRARIES</h4>
707<p>When linking Java apps and libraries, <code>LOCAL_JAVA_LIBRARIES</code>
708specifies which sets of java classes to include. Currently there are
709two of these: <code>core</code> and <code>framework</code>.
710In 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
715will 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
720very 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
724that are not part of the build for your executable or library. Specify
725the libraries you want in -lxxx format; they're passed directly to the
726link line. However, keep in mind that there will be no dependency generated
727for these libraries. It's most useful in simulator builds where you want
728to use a library preinstalled on the host. The linker (ld) is a particularly
729fussy beast, so it's sometimes necessary to pass other flags here if you're
730doing something sneaky. Some examples:</p>
731<p><code>LOCAL_LDLIBS += -lcurses -lpthread<br/>
732LOCAL_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
737set <code>LOCAL_NO_MANIFEST:=true</code>. The common resources package
738does this.</p>
739
740<h4>LOCAL_PACKAGE_NAME</h4>
741<p><code>LOCAL_PACKAGE_NAME</code> is the name of an app. For example,
742Dialer, Contacts, etc. This will probably change or go away when we switch
743to 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
747following 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>
751variable, so you must call it before you include any other makefiles. Also,
752consider that any subdirectories you inlcude might reset LOCAL_PATH, so do your
753own stuff before you include them. This also means that if you try to write
754several <code>include</code> lines that reference <code>LOCAL_PATH</code>,
755it 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
759after it's been linked. You might have to go through some contortions
760to get variables right because of early or late variable evaluation:</p>
761<p><code>module := $(HOST_OUT_EXECUTABLES)/$(LOCAL_MODULE)<br/>
762LOCAL_POST_PROCESS_COMMAND := /Developer/Tools/Rez -d __DARWIN__ -t APPL\<br/>
763&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-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
768executables that you want copied. They're located automatically into the
769right bin directory.</p>
770
771<h4>LOCAL_PREBUILT_LIBS</h4>
772<p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to
773libraries that you want copied. They're located automatically into the
774right 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
778pass transitively included libraries. Specify the name without the suffix:</p>
779<p><code>LOCAL_SHARED_LIBRARIES := \<br/>
780 &nbsp;&nbsp;&nbsp;&nbsp;libutils \<br/>
781 &nbsp;&nbsp;&nbsp;&nbsp;libui \<br/>
782 &nbsp;&nbsp;&nbsp;&nbsp;libaudio \<br/>
783 &nbsp;&nbsp;&nbsp;&nbsp;libexpat \<br/>
784 &nbsp;&nbsp;&nbsp;&nbsp;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
789files to compile -- .cpp .c .y .l .java. For lex and yacc files, it knows
790how to correctly do the intermediate .h and .c/.cpp files automatically. If
791the files are in a subdirectory of the one containing the Android.mk, prefix
792them with the directory name:</p>
793<p><code>LOCAL_SRC_FILES := \<br/>
794 &nbsp;&nbsp;&nbsp;&nbsp;file1.cpp \<br/>
795 &nbsp;&nbsp;&nbsp;&nbsp;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.
800Mostly, we use shared libraries, but there are a couple of places, like
801executables in sbin and host executables where we use static libraries instead.
802<p><code>LOCAL_STATIC_LIBRARIES := \<br/>
803 &nbsp;&nbsp;&nbsp;&nbsp;libutils \<br/>
804 &nbsp;&nbsp;&nbsp;&nbsp;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
809from your Android.mk. For exmample, for libkjs, the <code>LOCAL_MODULE</code>
810is "libkjs" (the build system adds the appropriate suffix -- .so .dylib .dll).
811For 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,
813so 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
817normal 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
819so the unstripped binary has somewhere to go. An error will occur if you forget
820to.</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
825somewhere other than what's normal for its type. Usually, you override this
826because you overrode <code>LOCAL_MODULE_PATH</code> for an executable or a
827shared 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
833the linker to remove dead code from them. This is mostly useful if you want to add a static library
834to a shared library and have the static library's content exposed from the shared library.
835<p><code>LOCAL_WHOLE_STATIC_LIBRARIES := \<br/>
836 &nbsp;&nbsp;&nbsp;&nbsp;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
841here is that the flags will be the same for all invocations of YACC for your
842module. 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
850you're adding a new platform, new tools, or adding new features to the
851build 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
853mucking around in here. That said, here are some notes on what's going on
854under 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
858it is necessary to make changes to buildspec.mk or to rerun the environment
859setup scripts, they contain a version number in the variable
860BUILD_ENV_SEQUENCE_NUMBER. If this variable does not match what the build
861system expects, it fails printing an error message explaining what happened.
862If you make a change that requires an update, you need to update two places
863so 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>
870The scripts automatically get the value from the build system, so they will
871trigger 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.
877These are mostly there for workarounds for other issues, or things that aren't
878completely done right.</p>
879
880<h4>LOCAL_ADDITIONAL_DEPENDENCIES</h4>
881<p>If your module needs to depend on anything else that
882isn't actually built in to it, you can add those make targets to
883<code>LOCAL_ADDITIONAL_DEPENDENCIES</code>. Usually this is a workaround
884for 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
888directory then copied to its final location. LOCAL_BUILT_MODULE is
889the full path to the intermediate file. See LOCAL_INSTALLED_MODULE
890for 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
894includes that we're building for the host. Kenneth did this as part of
895openbinder, and I would like to clean it up so the rules, includes and
896definitions 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.
900See LOCAL_BUILT_MODULE for the location of the intermediate file that
901the 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
905with particular values set,</p>
906
907<h4>LOCAL_SCRIPTS</h4>
908<p>Used in some stuff remaining from the openbinder build system that we
909might 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
913variable names used to locate the modules. See base_rules.make and
914envsetup.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,
918but it looks like it's just used in the WHO_AM_I variable to identify
919in 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
927be stripped or not, based on whether <code>LOCAL_STRIPPABLE_MODULE</code>
928is set, and whether the combo is configured to ever strip modules. With
929Iliyan'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.
933Executables 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
937it should be set to "none," as it is in $(CLEAR_VARS). When building
938these libraries, it's set to the ones they link against. For example,
939libc, libstdc++ and libdl don't link against anything, and libm links against
940libc. Normally, when the value is none, these libraries are automatically
941linked in to executables and libraries, so you don't need to specify them
942manually.</p>
943
944
945</body>
946</html>