1 # Build System Changes for Android.mk Writers 2 3 ## Deprecating / obsoleting envsetup.sh variables in Makefiles 4 5 It is not required to source envsetup.sh before running a build. Many scripts, 6 including a majority of our automated build systems, do not do so. Make will 7 transparently make every environment variable available as a make variable. 8 This means that relying on environment variables only set up in envsetup.sh will 9 produce different output for local users and scripted users. 10 11 Many of these variables also include absolute path names, which we'd like to 12 keep out of the generated files, so that you don't need to do a full rebuild if 13 you move the source tree. 14 15 To fix this, we're marking the variables that are set in envsetup.sh as 16 deprecated in the makefiles. This will trigger a warning every time one is read 17 (or written) inside Kati. Once all the warnings have been removed for a 18 particular variable, we'll switch it to obsolete, and any references will become 19 errors. 20 21 ### envsetup.sh variables with make equivalents 22 23 | instead of | use | 24 |--------------------------------------------------------------|----------------------| 25 | OUT {#OUT} | OUT_DIR | 26 | ANDROID_HOST_OUT {#ANDROID_HOST_OUT} | HOST_OUT | 27 | ANDROID_PRODUCT_OUT {#ANDROID_PRODUCT_OUT} | PRODUCT_OUT | 28 | ANDROID_HOST_OUT_TESTCASES {#ANDROID_HOST_OUT_TESTCASES} | HOST_OUT_TESTCASES | 29 | ANDROID_TARGET_OUT_TESTCASES {#ANDROID_TARGET_OUT_TESTCASES} | TARGET_OUT_TESTCASES | 30 31 All of the make variables may be relative paths from the current directory, or 32 absolute paths if the output directory was specified as an absolute path. If you 33 need an absolute variable, convert it to absolute during a rule, so that it's 34 not expanded into the generated ninja file: 35 36 ``` make 37 $(PRODUCT_OUT)/gen.img: my/src/path/gen.sh 38 export PRODUCT_OUT=$$(cd $(PRODUCT_OUT); pwd); cd my/src/path; ./gen.sh -o $${PRODUCT_OUT}/gen.img 39 ``` 40 41 ### ANDROID_BUILD_TOP {#ANDROID_BUILD_TOP} 42 43 In Android.mk files, you can always assume that the current directory is the 44 root of the source tree, so this can just be replaced with '.' (which is what 45 $TOP is hardcoded to), or removed entirely. If you need an absolute path, see 46 the instructions above. 47 48 ### Stop using PATH directly {#PATH} 49 50 This isn't only set by envsetup.sh, but it is modified by it. Due to that it's 51 rather easy for this to change between different shells, and it's not ideal to 52 reread the makefiles every time this changes. 53 54 In most cases, you shouldn't need to touch PATH at all. When you need to have a 55 rule reference a particular binary that's part of the source tree or outputs, 56 it's preferrable to just use the path to the file itself (since you should 57 already be adding that as a dependency). 58 59 Depending on the rule, passing the file path itself may not be feasible due to 60 layers of unchangable scripts/binaries. In that case, be sure to add the 61 dependency, but modify the PATH within the rule itself: 62 63 ``` make 64 $(TARGET): myscript my/path/binary 65 PATH=my/path:$$PATH myscript -o $@ 66 ``` 67 68 ### Stop using PYTHONPATH directly {#PYTHONPATH} 69 70 Like PATH, this isn't only set by envsetup.sh, but it is modified by it. Due to 71 that it's rather easy for this to change between different shells, and it's not 72 ideal to reread the makefiles every time. 73 74 The best solution here is to start switching to Soong's python building support, 75 which packages the python interpreter, libraries, and script all into one file 76 that no longer needs PYTHONPATH. See fontchain_lint for examples of this: 77 78 * [external/fonttools/Lib/fontTools/Android.bp] for python_library_host 79 * [frameworks/base/Android.bp] for python_binary_host 80 * [frameworks/base/data/fonts/Android.mk] to execute the python binary 81 82 If you still need to use PYTHONPATH, do so within the rule itself, just like 83 path: 84 85 ``` make 86 $(TARGET): myscript.py $(sort $(shell find my/python/lib -name '*.py')) 87 PYTHONPATH=my/python/lib:$$PYTHONPATH myscript.py -o $@ 88 ``` 89 ### Stop using PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE directly {#PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE} 90 91 Specify Framework Compatibility Matrix Version in device manifest by adding a `target-level` 92 attribute to the root element `<manifest>`. If `PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE` 93 is 26 or 27, you can add `"target-level"="1"` to your device manifest instead. 94 95 ### Stop using USE_CLANG_PLATFORM_BUILD {#USE_CLANG_PLATFORM_BUILD} 96 97 Clang is the default and only supported Android compiler, so there is no reason 98 for this option to exist. 99 100 ### Other envsetup.sh variables {#other_envsetup_variables} 101 102 * ANDROID_TOOLCHAIN 103 * ANDROID_TOOLCHAIN_2ND_ARCH 104 * ANDROID_DEV_SCRIPTS 105 * ANDROID_EMULATOR_PREBUILTS 106 * ANDROID_PRE_BUILD_PATHS 107 108 These are all exported from envsetup.sh, but don't have clear equivalents within 109 the makefile system. If you need one of them, you'll have to set up your own 110 version. 111 112 113 [build/soong/Changes.md]: https://android.googlesource.com/platform/build/soong/+/master/Changes.md 114 [external/fonttools/Lib/fontTools/Android.bp]: https://android.googlesource.com/platform/external/fonttools/+/master/Lib/fontTools/Android.bp 115 [frameworks/base/Android.bp]: https://android.googlesource.com/platform/frameworks/base/+/master/Android.bp 116 [frameworks/base/data/fonts/Android.mk]: https://android.googlesource.com/platform/frameworks/base/+/master/data/fonts/Android.mk 117
