1// Copyright 2015 Google Inc. All rights reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// Soong is a builder for Android that uses Blueprint to parse Blueprints
16// files and Ninja to do the dependency tracking and subprocess management.
17// Soong itself is responsible for converting the modules read by Blueprint
18// into build rules, which will be written to a build.ninja file by Blueprint.
19//
20// Android build concepts:
21//
22// Device
23// A device is a piece of hardware that will be running Android.  It may specify
24// global settings like architecture, filesystem configuration, initialization
25// scripts, and device drivers.  A device may support all variants of a single
26// piece of hardware, or multiple devices may be used for different variants.
27// A build is never targeted directly at a device, it is always targeted at a
28// "product".
29//
30// Product
31// A product is a configuration of a device, often for a specific market or
32// use case.  It is sometimes referred to as a "SKU".  A product defines
33// global settings like supported languages, supported use cases, preinstalled
34// modules, and user-visible behavior choices.  A product selects one and only
35// one device.
36//
37// Module
38// A module is a definition of something to be built.  It may be a C library or
39// binary, a java library, an Android app, etc.  A module may be built for multiple
40// targets, even in a single build, for example host and device, or 32-bit device
41// and 64-bit device.
42//
43// Installed module
44// An installed module is one that has been requested by the selected product,
45// or a dependency of an installed module.
46//
47// Target architecture
48// The target architecture is the preferred architecture supported by the selected
49// device.  It is most commonly 32-bit arm, but may also be 64-bit arm, 32-bit
50// x86, or 64-bit x86.
51//
52// Secondary architecture
53// The secondary architecture specifies the architecture to compile a second copy
54// of some modules for devices that support multiple architectures, for example
55// 64-bit devices that also support 32-bit binaries.
56package soong
57