android build policy

There is a file about building android in details in the android/build 
folder. I paste the contents here: 
Android Build System 
Status: Draft   (as of May 18, 2006) 

Contents 

Objective 
The primary goals of reworking the build system are (1) to make 
dependencies work more reliably, so that when files need to rebuilt, 
they are, and (2) to improve performance of the build system so that 
unnecessary modules are not rebuilt, and so doing a top-level build 
when little or nothing needs to be done for a build takes as little 
time as possible. 

Principles and Use Cases and Policy 
Given the above objective, these are the overall principles and use 
cases that we will support. This is not an exhaustive list. 

Multiple Targets 
It needs to be possible to build the Android platform for multiple 
targets. This means: 

The build system will support building tools for the host platform, 
both ones that are used in the build process itself, and developer 
tools like the simulator. 
The build system will need to be able to build tools on Linux 
(definitely Goobuntu and maybe Grhat), MacOS, and to some degree on 
Windows. 
The build system will need to be able to build the OS on Linux, and in 
the short-term, MacOS. Note that this is a conscious decision to stop 
building the OS on Windows. We are going to rely on the emulator there 
and not attempt to use the simulator. This is a requirement change now 
that the emulator story is looking brighter. 
Non-Recursive Make 
To achieve the objectives, the build system will be rewritten to use 
make non-recursively. For more background on this, read Recursive Make 
Considered Harmful. For those that don't want PDF, here is the Google 
translated version. 

Rapid Compile-Test Cycles 
When developing a component, for example a C++ shared library, it must 
be possible to easily rebuild just that component, and not have to 
wait more than a couple seconds for dependency checks, and not have to 
wait for unneeded components to be built. 

Both Environment and Config File Based Settings 
To set the target, and other options, some people on the team like to 
have a configuration file in a directory so they do not have an 
environment setup script to run, and others want an environment setup 
script to run so they can run builds in different terminals on the 
same tree, or switch back and forth in one terminal. We will support 
both. 

Object File Directory / make clean 
Object files and other intermediate files will be generated into a 
directory that is separate from the source tree. The goal is to have 
make clean be "rm -rf " in the tree root directory. The primary goals 
of this are to simplify searching the source tree, and to make "make 
clean" more reliable. 

SDK 
The SDK will be a tarball that will allow non-OS-developers to write 
apps. The apps will actually be built by first building the SDK, and 
then building the apps against that SDK. This will hopefully (1) make 
writing apps easier for us, because we won't have to rebuild the OS as 
much, and we can use the standard java-app development tools, and (2) 
allow us to dog-food the SDK, to help ensure its quality. Cedric has 
suggested (and I agree) that apps built from the SDK should be built 
with ant. Stay tuned for more details as we figure out exactly how 
this will work. 

Dependecies 
Dependencies should all be automatic. Unless there is a custom tool 
involved (e.g. the webkit has several), the dependencies for shared 
and static libraries, .c, .cpp, .h, .java, java libraries, etc., 
should all work without intervention in the Android.mk file. 

Hiding command lines 
The default of the build system will be to hide the command lines 
being executed for make steps. It will be possible to override this by 
specifying the showcommands pseudo-target, and possibly by setting an 
environment variable. 

Wildcard source files 
Wildcarding source file will be discouraged. It may be useful in some 
scenarios. The default $(wildcard *) will not work due to the current 
directory being set to the root of the build tree. 

Multiple targets in one directory 
It will be possible to generate more than one target from a given 
subdirectory. For example, libutils generates a shared library for the 
target and a static library for the host. 

Makefile fragments for modules 
Android.mk is the standard name for the makefile fragments that 
control the building of a given module. Only the top directory should 
have a file named "Makefile". 

Use shared libraries 
Currently, the simulator is not built to use shared libraries. This 
should be fixed, and now is a good time to do it. This implies getting 
shared libraries to work on Mac OS. 

Nice to Have 
These things would be nice to have, and this is a good place to record 
them, however these are not promises. 

Simultaneous Builds 
The hope is to be able to do two builds for different combos in the 
same tree at the same time, but this is a stretch goal, not a 
requirement. Doing two builds in the same tree, not at the same time 
must work. (update: it's looking like we'll get the two builds at the 
same time working) 

Deleting headers (or other dependecies) 
Problems can arise if you delete a header file that is referenced in 
".d" files. The easy way to deal with this is "make clean". There 
should be a better way to handle it. (from fadden) 

One way of solving this is introducing a dependency on the directory. 
The problem is that this can create extra dependecies and slow down 
the build. It's a tradeoff. 

Multiple builds 
General way to perform builds across the set of known platforms. This 
would make it easy to perform multiple platform builds when testing a 
change, and allow a wide-scale "make clean". Right now the 
buildspec.mk or environment variables need to be updated before each 
build. (from fadden) 

Aftermarket Locales and Carrier 
We will eventually need to add support for creating locales and 
carrier customizations to the SDK, but that will not be addressed 
right now. 

Usage 
You've read (or scrolled past) all of the motivations for this build 
system, and you want to know how to use it. This is the place. 

Your first build 
The Building document describes how do do builds. 

build/envsetup.sh functions 
If you source the file build/envsetup.sh into your bash environment, . 
build/envsetup.shyou'll get a few helpful shell functions: 
printconfig - Prints the current configuration as set by the lunch and 
choosecombo commands. 
m - Runs make from the top of the tree. This is useful because you can 
run make from within subdirectories. If you have the TOP environment 
variable set, it uses that. If you don't, it looks up the tree from 
the current directory, trying to find the top of the tree. 
croot - cd to the top of the tree. 
sgrep - grep for the regex you provide in all .c, .cpp, .h, .java, 
and .xml files below the current directory. 
Build flavors/types 
When building for a particular product, it's often useful to have 
minor variations on what is ultimately the final release build. These 
are the currently-defined "flavors" or "types" (we need to settle on a 
real name for these). 

eng  This is the default flavor. A plain "make" is the same as "make 
eng". droid is an alias for eng. 
Installs modules tagged with: eng, debug, user, and/or development. 
Installs non-APK modules that have no tags specified. 
Installs APKs according to the product definition files, in addition 
to tagged APKs. 
ro.secure=0 
ro.debuggable=1 
ro.kernel.android.checkjni=1 
adb is enabled by default. 

user  "make user" 
This is the flavor intended to be the final release bits. 

Installs modules tagged with user. 
Installs non-APK modules that have no tags specified. 
Installs APKs according to the product definition files; tags are 
ignored for APK modules. 
ro.secure=1 
ro.debuggable=0 
adb is disabled by default. 

userdebug  "make userdebug" 
The same as user, except: 

Also installs modules tagged with debug. 
ro.debuggable=1 
adb is enabled by default. 

If you build one flavor and then want to build another, you should run 
"make installclean" between the two makes to guarantee that you don't 
pick up files installed by the previous flavor. "make clean" will also 
suffice, but it takes a lot longer. 

More pseudotargets 
Sometimes you want to just build one thing. The following 
pseudotargets are there for your convenience: 

droid - make droid is the normal build. This target is here because 
the default target has to have a name. 
all - make all builds everything make droid does, plus everything 
whose LOCAL_MODULE_TAGS do not include the "droid" tag. The build 
server runs this to make sure that everything that is in the tree and 
has an Android.mk builds. 
clean-$(LOCAL_MODULE) and clean-$(LOCAL_PACKAGE_NAME) - Let you 
selectively clean one target. For example, you can type make clean- 
libutils and it will delete libutils.so and all of the intermediate 
files, or you can type make clean-Home and it will clean just the Home 
app. 
clean - make clean deletes all of the output and intermediate files 
for this configuration. This is the same as rm -rf out/ 
<configuration>/ 
clobber - make clobber deletes all of the output and intermediate 
files for all configurations. This is the same as rm -rf out/. 
dataclean - make dataclean deletes contents of the data directory 
inside the current combo directory. This is especially useful on the 
simulator and emulator, where the persistent data remains present 
between builds. 
showcommands - showcommands is a modifier target which causes the 
build system to show the actual command lines for the build steps, 
instead of the brief descriptions. Most people don't like seeing the 
actual commands, because they're quite long and hard to read, but if 
you need to for debugging purposes, you can add showcommands to the 
list of targets you build. For example make showcommands will build 
the default android configuration, and make runtime showcommands will 
build just the runtime, and targets that it depends on, while 
displaying the full command lines. Please note that there are a couple 
places where the commands aren't shown here. These are considered 
bugs, and should be fixed, but they're often hard to track down. 
Please let android-build-team know if you find any. 
LOCAL_MODULE - Anything you specify as a LOCAL_MODULE in an Android.mk 
is made into a pseudotarget. For example, make runtime might be 
shorthand for make out/linux-x86-debug/system/bin/runtime (which would 
work), and make libkjs might be shorthand for make out/linux-x86-debug/ 
system/lib/libkjs.so (which would also work). 
targets - make targets will print a list of all of the LOCAL_MODULE 
names you can make. 
How to add another component to the build - Android.mk templates 
You have a new library, a new app, or a new executable. For each of 
the common types of modules, there is a corresponding file in the 
templates directory. It will usually be enough to copy one of these, 
and fill in your own values. Some of the more esoteric values are not 
included in the templates, but are instead just documented here, as is 
the documentation on using custom tools to generate files. 

Mostly, you can just look for the TODO comments in the templates and 
do what it says. Please remember to delete the TODO comments when 
you're done to keep the files clean. The templates have minimal 
documentation in them, because they're going to be copied, and when 
that gets stale, the copies just won't get updated. So read on... 

Apps 
Use the templates/apps file. 

This template is pretty self-explanitory. See the variables below for 
more details. 

Java Libraries 
Use the templates/java_library file. 

The interesting thing here is the value of LOCAL_MODULE, which becomes 
the name of the jar file. (Actually right now, we're not making jar 
files yet, just directories of .class files, but the directory is 
named according to what you put in LOCAL_MODULE). This name will be 
what goes in the LOCAL_JAVA_LIBRARIES variable in modules that depend 
on your java library. 

C/C++ Executables 
Use the templates/executable file, or the templates/executable_host 
file. 

This template has a couple extra options that you usually don't need. 
Please delete the ones you don't need, and remove the TODO comments. 
It makes the rest of them easier to read, and you can always refer 
back to the templates if you need them again later. 

By default, on the target these are built into /system/bin, and on the 
host, they're built into /host/bin. These can be overridden by setting 
LOCAL_MODULE_PATH. See Putting targets elsewhere for more. 

Shared Libraries 
Use the templates/shared_library file, or the templates/ 
shared_library_host file. 

Remember that on the target, we use shared libraries, and on the host, 
we use static libraries, since executable size isn't as big an issue, 
and it simplifies distribution in the SDK. 

Static Libraries 
Use the templates/static_library file, or the templates/ 
static_library_host file. 

Remember that on the target, we use shared libraries, and on the host, 
we use static libraries, since executable size isn't as big an issue, 
and it simplifies distribution in the SDK. 

Using Custom Tools 
If you have a tool that generates source files for you, it's possible 
to have the build system get the dependencies correct for it. Here are 
a couple of examples. $@ is the make built-in variable for "the 
current target." The red parts are the parts you'll need to change. 

You need to put this after you have declared LOCAL_PATH and 
LOCAL_MODULE, because the $(local-intermediates-dir) and $(local-host- 
intermediates-dir) macros use these variables to determine where to 
put the files. 

Example 1 
Here, there is one generated file, called chartables.c, which doesn't 
depend on anything. And is built by the tool built to $ 
(HOST_OUT_EXECUTABLES)/dftables. Note on the second to last line that 
a dependency is created on the tool. 

intermediates:= $(local-intermediates-dir) 
GEN := $(intermediates)/chartables.c 
$(GEN): PRIVATE_CUSTOM_TOOL = $(HOST_OUT_EXECUTABLES)/dftables $@ 
$(GEN): $(HOST_OUT_EXECUTABLES)/dftables 
        $(transform-generated-source) 
LOCAL_GENERATED_SOURCES += $(GEN) 
Example 2 
Here as a hypothetical example, we use use cat as if it were to 
transform a file. Pretend that it does something useful. Note how we 
use a target-specific variable called PRIVATE_INPUT_FILE to store the 
name of the input file. 

intermediates:= $(local-intermediates-dir) 
GEN := $(intermediates)/file.c 
$(GEN): PRIVATE_INPUT_FILE := $(LOCAL_PATH)/input.file 
$(GEN): PRIVATE_CUSTOM_TOOL = cat $(PRIVATE_INPUT_FILE) > $@ 
$(GEN): $(LOCAL_PATH)/file.c 
        $(transform-generated-source) 
LOCAL_GENERATED_SOURCES += $(GEN) 
Example 3 
If you have several files that are all similar in name, and use the 
same tool, you can combine them. (here the *.lut.h files are the 
generated ones, and the *.cpp files are the input files) 

intermediates:= $(local-intermediates-dir) 
GEN := $(addprefix $(intermediates)/kjs/, \ 
            array_object.lut.h \ 
            bool_object.lut.h \ 
        ) 
$(GEN): PRIVATE_CUSTOM_TOOL = perl libs/WebKitLib/WebKit/ 
JavaScriptCore/kjs/create_hash_table $< -i > $@ 
$(GEN): $(intermediates)/%.lut.h : $(LOCAL_PATH)/%.cpp 
        $(transform-generated-source) 
LOCAL_GENERATED_SOURCES += $(GEN) 
Platform specific conditionals 
Sometimes you need to set flags specifically for different platforms. 
Here is a list of which values the different build-system defined 
variables will be set to and some examples. 

For a device build, TARGET_OS is linux (we're using linux!), and 
TARGET_ARCH is arm. 

For a simulator build, TARGET_OS and TARGET_ARCH are set to the same 
as HOST_OS and HOST_ARCH are on your platform. TARGET_PRODUCT is the 
name of the target hardware/product you are building for. The value 
sim is used for the simulator. We haven't thought through the full 
extent of customization that will happen here, but likely there will 
be additional UI configurations specified here as well. 

HOST_OS 
linux 
darwin 
(cygwin)  HOST_ARCH 
x86  HOST_BUILD_TYPE 
release 
debug 
TARGET_OS 
linux 
darwin 
(cygwin)  TARGET_ARCH 
arm 
x86  TARGET_BUILD_TYPE 
release 
debug  TARGET_PRODUCT 
sim 
dream 
sooner 

TARGET_SIMULATOR 
If we're building the simulator, as opposed to the arm or emulator 
builds, TARGET_SIMULATOR will be set to true. 

Some Examples 
ifeq ($(TARGET_SIMULATOR),true) 
LOCAL_CFLAGS += -DSIMULATOR 
endif 

ifeq ($(TARGET_BUILD_TYPE),release) 
LOCAL_CFLAGS += -DNDEBUG=1 
endif 

# from libutils 
ifeq ($(TARGET_OS),linux) 
# Use the futex based mutex and condition variable 
# implementation from android-arm because it's shared mem safe 
LOCAL_SRC_FILES += futex_synchro.c 
LOCAL_LDLIBS += -lrt -ldl 
endif 

Putting modules elsewhere 
If you have modules that normally go somewhere, and you need to have 
them build somewhere else, read this. One use of this is putting files 
on the root filesystem instead of where they normally go in /system. 
Add these lines to your Android.mk: 

LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN) 
LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED) 
For executables and libraries, you need to also specify a 
LOCAL_UNSTRIPPED_PATH location, because on target builds, we keep the 
unstripped executables so GDB can find the symbols. 

Look in config/envsetup.make for all of the variables defining places 
to build things. 

FYI: If you're installing an executable to /sbin, you probably also 
want to set LOCAL_FORCE_STATIC_EXCUTABLE := true in your Android.mk, 
which will force the linker to only accept static libraries. 

Android.mk variables 
These are the variables that you'll commonly see in Android.mk files, 
listed alphabetically. 

But first, a note on variable naming: 

LOCAL_ - These variables are set per-module. They are cleared by the 
include $(CLEAR_VARS) line, so you can rely on them being empty after 
including that file. Most of the variables you'll use in most modules 
are LOCAL_ variables. 
PRIVATE_ - These variables are make-target-specific variables. That 
means they're only usable within the commands for that module. It also 
means that they're unlikely to change behind your back from modules 
that are included after yours. This link to the make documentation 
describes more about target-specific variables. Please note that there 
are a couple of these laying around the tree that aren't prefixed with 
PRIVATE_. It is safe, and they will be fixed as they are discovered. 
Sorry for the confusion. 
INTERNAL_ - These variables are critical to functioning of the build 
system, so you shouldn't create variables named like this, and you 
probably shouldn't be messing with these variables in your makefiles. 
HOST_ and TARGET_ - These contain the directories and definitions that 
are specific to either the host or the target builds. Do not set 
variables that start with HOST_ or TARGET_ in your makefiles. 
BUILD_ and CLEAR_VARS - These contain the names of well-defined 
template makefiles to include. Some examples are CLEAR_VARS and 
BUILD_HOST_PACKAGE. 
Any other name is fair-game for you to use in your Android.mk. 
However, remember that this is a non-recursive build system, so it is 
possible that your variable will be changed by another Android.mk 
included later, and be different when the commands for your rule / 
module are executed. 

LOCAL_ASSET_FILES 
In Android.mk files that include $(BUILD_PACKAGE) set this to the set 
of files you want built into your app. Usually: 

LOCAL_ASSET_FILES += $(call find-subdir-assets) 

This will probably change when we switch to ant for the apps' build 
system. 

LOCAL_CC 
If you want to use a different C compiler for this module, set 
LOCAL_CC to the path to the compiler. If LOCAL_CC is blank, the 
appropriate default compiler is used. 

LOCAL_CXX 
If you want to use a different C++ compiler for this module, set 
LOCAL_CXX to the path to the compiler. If LOCAL_CXX is blank, the 
appropriate default compiler is used. 

LOCAL_CFLAGS 
If you have additional flags to pass into the C or C++ compiler, add 
them here. For example: 

LOCAL_CFLAGS += -DLIBUTILS_NATIVE=1 

LOCAL_CPPFLAGS 
If you have additional flags to pass into only the C++ compiler, add 
them here. For example: 

LOCAL_CPPFLAGS += -ffriend-injection 

LOCAL_CPPFLAGS is guaranteed to be after LOCAL_CFLAGS on the compile 
line, so you can use it to override flags listed in LOCAL_CFLAGS. 
LOCAL_CPP_EXTENSION 
If your C++ files end in something other than ".cpp", you can specify 
the custom extension here. For example: 

LOCAL_CPP_EXTENSION := .cc 

Note that all C++ files for a given module must have the same 
extension; it is not currently possible to mix different extensions. 
LOCAL_NO_DEFAULT_COMPILER_FLAGS 
Normally, the compile line for C and C++ files includes global include 
paths and global cflags. If LOCAL_NO_DEFAULT_COMPILER_FLAGS is non- 
empty, none of the default includes or flags will be used when 
compiling C and C++ files in this module. LOCAL_C_INCLUDES, 
LOCAL_CFLAGS, and LOCAL_CPPFLAGS will still be used in this case, as 
will any DEBUG_CFLAGS that are defined for the module. 

LOCAL_COPY_HEADERS 
This will be going away. 

The set of files to copy to the install include tree. You must also 
supply LOCAL_COPY_HEADERS_TO. 

This is going away because copying headers messes up the error 
messages, and may lead to people editing those headers instead of the 
correct ones. It also makes it easier to do bad layering in the 
system, which we want to avoid. We also aren't doing a C/C++ SDK, so 
there is no ultimate requirement to copy any headers. 

LOCAL_COPY_HEADERS_TO 
This will be going away. 

The directory within "include" to copy the headers listed in 
LOCAL_COPY_HEADERS to. 

This is going away because copying headers messes up the error 
messages, and may lead to people editing those headers instead of the 
correct ones. It also makes it easier to do bad layering in the 
system, which we want to avoid. We also aren't doing a C/C++ SDK, so 
there is no ultimate requirement to copy any headers. 

LOCAL_C_INCLUDES 
Additional directories to instruct the C/C++ compilers to look for 
header files in. These paths are rooted at the top of the tree. Use 
LOCAL_PATH if you have subdirectories of your own that you want in the 
include paths. For example: 

LOCAL_C_INCLUDES += extlibs/zlib-1.2.3 
LOCAL_C_INCLUDES += $(LOCAL_PATH)/src 

You should not add subdirectories of include to LOCAL_C_INCLUDES, 
instead you should reference those files in the #include statement 
with their subdirectories. For example: 

#include <utils/KeyedVector.h> 
not #include <KeyedVector.h> 

There are some components that are doing this wrong, and should be 
cleaned up. 

LOCAL_MODULE_TAGS 
Set LOCAL_MODULE_TAGS to any number of whitespace-separated tags. If 
the tag list is empty or contains droid, the module will get installed 
as part of a make droid. Otherwise, it will only get installed by 
running make <your-module> or with the make all pseudotarget. 

LOCAL_REQUIRED_MODULES 
Set LOCAL_REQUIRED_MODULES to any number of whitespace-separated 
module names, like "libblah" or "Email". If this module is installed, 
all of the modules that it requires will be installed as well. This 
can be used to, e.g., ensure that necessary shared libraries or 
providers are installed when a given app is installed. 

LOCAL_FORCE_STATIC_EXECUTABLE 
If your executable should be linked statically, set 
LOCAL_FORCE_STATIC_EXECUTABLE:=true. There is a very short list of 
libraries that we have in static form (currently only libc). This is 
really only used for executables in /sbin on the root filesystem. 

LOCAL_GENERATED_SOURCES 
Files that you add to LOCAL_GENERATED_SOURCES will be automatically 
generated and then linked in when your module is built. See the Custom 
Tools template makefile for an example. 

LOCAL_JAVA_LIBRARIES 
When linking Java apps and libraries, LOCAL_JAVA_LIBRARIES specifies 
which sets of java classes to include. Currently there are two of 
these: core and framework. In most cases, it will look like this: 

LOCAL_JAVA_LIBRARIES := core framework 

Note that setting LOCAL_JAVA_LIBRARIES is not necessary (and is not 
allowed) when building an APK with "include $(BUILD_PACKAGE)". The 
appropriate libraries will be included automatically. 

LOCAL_LDFLAGS 
You can pass additional flags to the linker by setting LOCAL_LDFLAGS. 
Keep in mind that the order of parameters is very important to ld, so 
test whatever you do on all platforms. 

LOCAL_LDLIBS 
LOCAL_LDLIBS allows you to specify additional libraries that are not 
part of the build for your executable or library. Specify the 
libraries you want in -lxxx format; they're passed directly to the 
link line. However, keep in mind that there will be no dependency 
generated for these libraries. It's most useful in simulator builds 
where you want to use a library preinstalled on the host. The linker 
(ld) is a particularly fussy beast, so it's sometimes necessary to 
pass other flags here if you're doing something sneaky. Some examples: 

LOCAL_LDLIBS += -lcurses -lpthread 
LOCAL_LDLIBS += -Wl,-z,origin 

LOCAL_NO_MANIFEST 
If your package doesn't have a manifest (AndroidManifest.xml), then 
set LOCAL_NO_MANIFEST:=true. The common resources package does this. 

LOCAL_PACKAGE_NAME 
LOCAL_PACKAGE_NAME is the name of an app. For example, Dialer, 
Contacts, etc. This will probably change or go away when we switch to 
an ant-based build system for the apps. 

LOCAL_PATH 
The directory your Android.mk file is in. You can set it by putting 
the following as the first line in your Android.mk: 

LOCAL_PATH := $(my-dir) 

The my-dir macro uses the MAKEFILE_LIST variable, so you must call it 
before you include any other makefiles. Also, consider that any 
subdirectories you inlcude might reset LOCAL_PATH, so do your own 
stuff before you include them. This also means that if you try to 
write several include lines that reference LOCAL_PATH, it won't work, 
because those included makefiles might reset LOCAL_PATH. 

LOCAL_POST_PROCESS_COMMAND 
For host executables, you can specify a command to run on the module 
after it's been linked. You might have to go through some contortions 
to get variables right because of early or late variable evaluation: 

module := $(HOST_OUT_EXECUTABLES)/$(LOCAL_MODULE) 
LOCAL_POST_PROCESS_COMMAND := /Developer/Tools/Rez -d __DARWIN__ -t 
APPL\ 
       -d __WXMAC__ -o $(module) Carbon.r 

LOCAL_PREBUILT_EXECUTABLES 
When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these 
to executables that you want copied. They're located automatically 
into the right bin directory. 

LOCAL_PREBUILT_LIBS 
When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these 
to libraries that you want copied. They're located automatically into 
the right lib directory. 

LOCAL_SHARED_LIBRARIES 
These are the libraries you directly link against. You don't need to 
pass transitively included libraries. Specify the name without the 
suffix: 

LOCAL_SHARED_LIBRARIES := \ 
    libutils \ 
    libui \ 
    libaudio \ 
    libexpat \ 
    libsgl 

LOCAL_SRC_FILES 
The build system looks at LOCAL_SRC_FILES to know what source files to 
compile -- .cpp .c .y .l .java. For lex and yacc files, it knows how 
to correctly do the intermediate .h and .c/.cpp files automatically. 
If the files are in a subdirectory of the one containing the 
Android.mk, prefix them with the directory name: 

LOCAL_SRC_FILES := \ 
    file1.cpp \ 
    dir/file2.cpp 

LOCAL_STATIC_LIBRARIES 
These are the static libraries that you want to include in your 
module. Mostly, we use shared libraries, but there are a couple of 
places, like executables in sbin and host executables where we use 
static libraries instead. 

LOCAL_STATIC_LIBRARIES := \ 
    libutils \ 
    libtinyxml 

LOCAL_MODULE 
LOCAL_MODULE is the name of what's supposed to be generated from your 
Android.mk. For exmample, for libkjs, the LOCAL_MODULE is 
"libkjs" (the build system adds the appropriate suffix 
-- .so .dylib .dll). For app modules, use LOCAL_PACKAGE_NAME instead 
of LOCAL_MODULE. We're planning on switching to ant for the apps, so 
this might become moot. 

LOCAL_MODULE_PATH 
Instructs the build system to put the module somewhere other than 
what's normal for its type. If you override this, make sure you also 
set LOCAL_UNSTRIPPED_PATH if it's an executable or a shared library so 
the unstripped binary has somewhere to go. An error will occur if you 
forget to. 

See Putting modules elsewhere for more. 

LOCAL_UNSTRIPPED_PATH 
Instructs the build system to put the unstripped version of the module 
somewhere other than what's normal for its type. Usually, you override 
this because you overrode LOCAL_MODULE_PATH for an executable or a 
shared library. If you overrode LOCAL_MODULE_PATH, but not 
LOCAL_UNSTRIPPED_PATH, an error will occur. 

See Putting modules elsewhere for more. 

LOCAL_WHOLE_STATIC_LIBRARIES 
These are the static libraries that you want to include in your module 
without allowing the linker to remove dead code from them. This is 
mostly useful if you want to add a static library to a shared library 
and have the static library's content exposed from the shared 
library. 

LOCAL_WHOLE_STATIC_LIBRARIES := \ 
    libsqlite3_android 

LOCAL_YACCFLAGS 
Any flags to pass to invocations of yacc for your module. A known 
limitation here is that the flags will be the same for all invocations 
of YACC for your module. This can be fixed. If you ever need it to be, 
just ask. 

LOCAL_YACCFLAGS := -p kjsyy 

Implementation Details 
You should never have to touch anything in the config directory unless 
you're adding a new platform, new tools, or adding new features to the 
build system. In general, please consult with the build system owner 
(s) (android-build-team) before you go mucking around in here. That 
said, here are some notes on what's going on under the hood. 

Environment Setup / buildspec.mk Versioning 
In order to make easier for people when the build system changes, when 
it is necessary to make changes to buildspec.mk or to rerun the 
environment setup scripts, they contain a version number in the 
variable BUILD_ENV_SEQUENCE_NUMBER. If this variable does not match 
what the build system expects, it fails printing an error message 
explaining what happened. If you make a change that requires an 
update, you need to update two places so this message will be 
printed. 

In config/envsetup.make, increment the 
CORRECT_BUILD_ENV_SEQUENCE_NUMBER definition. 
In buildspec.mk.default, update the BUILD_ENV_SEQUENCE_DUMBER 
definition to match the one in config/envsetup.make 
The scripts automatically get the value from the build system, so they 
will trigger the warning as well. 

Additional makefile variables 
You probably shouldn't use these variables. Please consult android- 
build-team before using them. These are mostly there for workarounds 
for other issues, or things that aren't completely done right. 

LOCAL_ADDITIONAL_DEPENDENCIES 
If your module needs to depend on anything else that isn't actually 
built in to it, you can add those make targets to 
LOCAL_ADDITIONAL_DEPENDENCIES. Usually this is a workaround for some 
other dependency that isn't created automatically. 

LOCAL_BUILT_MODULE 
When a module is built, the module is created in an intermediate 
directory then copied to its final location. LOCAL_BUILT_MODULE is the 
full path to the intermediate file. See LOCAL_INSTALLED_MODULE for the 
path to the final installed location of the module. 

LOCAL_HOST 
Set by the host_xxx.make includes to tell base_rules.make and the 
other includes that we're building for the host. Kenneth did this as 
part of openbinder, and I would like to clean it up so the rules, 
includes and definitions aren't duplicated for host and target. 

LOCAL_INSTALLED_MODULE 
The fully qualified path name of the final location of the module. See 
LOCAL_BUILT_MODULE for the location of the intermediate file that the 
make rules should actually be constructing. 

LOCAL_REPLACE_VARS 
Used in some stuff remaining from the openbinder for building scripts 
with particular values set, 

LOCAL_SCRIPTS 
Used in some stuff remaining from the openbinder build system that we 
might find handy some day. 

LOCAL_MODULE_CLASS 
Which kind of module this is. This variable is used to construct other 
variable names used to locate the modules. See base_rules.make and 
envsetup.make. 

LOCAL_MODULE_NAME 
Set to the leaf name of the LOCAL_BUILT_MODULE. I'm not sure, but it 
looks like it's just used in the WHO_AM_I variable to identify in the 
pretty printing what's being built. 

LOCAL_MODULE_SUFFIX 
The suffix that will be appended to LOCAL_MODULE to form 
LOCAL_MODULE_NAME. For example, .so, .a, .dylib. 

LOCAL_STRIP_MODULE 
Calculated in base_rules.make to determine if this module should 
actually be stripped or not, based on whether LOCAL_STRIPPABLE_MODULE 
is set, and whether the combo is configured to ever strip modules. 
With Iliyan's stripping tool, this might change. 

LOCAL_STRIPPABLE_MODULE 
Set by the include makefiles if that type of module is strippable. 
Executables and shared libraries are. 

LOCAL_SYSTEM_SHARED_LIBRARIES 
Used while building the base libraries: libc, libm, libdl. Usually it 
should be set to "none," as it is in $(CLEAR_VARS). When building 
these libraries, it's set to the ones they link against. For example, 
libc, libstdc++ and libdl don't link against anything, and libm links 
against libc. Normally, when the value is none, these libraries are 
automatically linked in to executables and libraries, so you don't 
need to specify them manually.