守正
分类： 嵌入式
2010-06-04 19:22:04
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 .
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.
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 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
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.
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.
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.
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.
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.
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".
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.
These things would be nice to have, and this is a good place to record them, however these are not promises.
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)
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.
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)
We will eventually need to add support for creating locales and carrier customizations to the SDK, but that will not be addressed right now.
document describes how do do builds.
.
build/envsetup.shyou'll get a few helpful shell functions:
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.
cd to the
top of the tree.
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.
|
user |
"make user"
This is the flavor intended to be the final release bits.
|
userdebug |
"make userdebug"
The same as
|
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.
Sometimes you want to just build one thing. The following pseudotargets are there for your convenience:
make droid is
the normal build. This target is here because the default target has to
have a name.
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.
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.
make clean
deletes all of the output and intermediate files for this configuration.
This is the same as rm -rf
out//
make clobber
deletes all of the output and intermediate files for all
configurations. This is the same as rm -rf out/.
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
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
know if you find any.
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).
make targets
will print a list of all of the LOCAL_MODULE names you can make. Use the templates/executable
file, or the templates/executable_host
file.
for more.
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.
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.
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)
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)
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)
For a device build, TARGET_OS is linux
(we're using linux!), and TARGET_ARCH
is arm.
| 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 |
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.
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.
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.
If you have additional flags to pass into the C or C++ compiler, add them here. For example:
LOCAL_CFLAGS += -DLIBUTILS_NATIVE=1
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.
If your C++ files end in something other than ".cpp",
you can specify the custom extension here. For example:
LOCAL_CPP_EXTENSION := .cc
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.
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.
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.
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
not
#include
There are some components that are doing this wrong, and should be cleaned up.
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
or with the make
all pseudotarget.
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.
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.
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.
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.
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 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
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 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.
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 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.
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
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.
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.
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
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
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 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.
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 for more.
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 for more.
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
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
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) () before you go mucking around in here. That said, here are some notes on what's going on under the hood.
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.
You probably shouldn't use these variables. Please consult before using them. These are mostly there for workarounds for other issues, or things that aren't completely done right.
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.
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.
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.
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.
Used in some stuff remaining from the openbinder for building scripts with particular values set,
Used in some stuff remaining from the openbinder build system that we might find handy some day.
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.
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.
The suffix that will be appended to LOCAL_MODULE
to form LOCAL_MODULE_NAME. For
example, .so, .a, .dylib.
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.
Set by the include makefiles if that type of module is strippable. Executables and shared libraries are.
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.