146 lines
5.0 KiB
Markdown
146 lines
5.0 KiB
Markdown
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# mkcompare: Compare generated Android-TARGET.mk makefiles
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## Summary
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This tool shows the differences between two `Android-`_target_`.mk` makefile.
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This makefile contains information about the Soong build graph that is exposed
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to Make (Android.mk) and packaging rules.
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## Usage
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```shell
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# run product config
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$ lunch ${target}
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# run soong for reference build
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$ m nothing && cp out/soong/Android-${target}.mk Android-${target}.mk.ref
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# apply your local changes..
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$ m nothing && cp out/soong/Android-${target}.mk Android-${target}.mk.new
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# compare!
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$ GOWORK=$PWD/build/bazel/mkcompare/go.work go run android/bazel/mkcompare/cmd \
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-json \
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Android-${target}.mk.ref \
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Android-${target}.mk.new > ${target}.mk.json
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```
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## Options ##
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The comparator optionally:
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* Generates a JSON file with all the differences (`-json`). This option turns off all out output.
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* Stops after finding given _N_ different modules `-m N`)
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* Ignores variables with given names (`--ignore_variables=VAR,...`)
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* Shows per-variable value difference (`--show_module_diffs`)
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* For each module type, shows the names of the modules with this difference (`--show_type_modules`)
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## How it works
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We assume that both makefiles were generated for the same configuration (i.e.,
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the same _target_ value, and our goal is thus to find out the difference that
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a change contributes to the Makefile interface between Soong and Make.
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Currently, the comparator inspects only the module sections of a file.
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A _module section_ looks something like this:
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```makefile
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include $(CLEAR_VARS) # <module type>
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LOCAL_MODULE := mymod
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LOCAL_MODULE_CLASS := ETC
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include $(BUILD_PREBUILT)
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```
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i.e., it always starts with `include $(CLEAR_VARS)` ('module header') line
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and spans until the blank line. Before a blank line there is an
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`include <mkfile>` line ('module footer'), which may be followed by a few extra
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variable assignments. Between those two `include ` lines are the assignment lines.
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The name of the module is synthesized from the value of the `LOCAL_MODULE` variable
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and target configuration, e.g, `apex_tzdata.com.android.tzdata|cls:ETC|target_arch:arm64`
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or `aac_dec_fuzzer|cls:EXECUTABLES|host_arch:x86_64`
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The module header includes the module type as a comment (the plan was to use the
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_mkfile_ on the footer line, but it proved to be common to most of the modules,
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so Soong was modified to provide a module detailed module type as a comment
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on the header line).
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A module section in the reference file is compared with the
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identically named module section of our file. The following items are compared:
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* module types
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* the number of extra lines following the section footer
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* the variables and their values
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## Summary Output
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The default outputs look as follows:
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```
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159 missing modules, by type:
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apex.apexBundle.files (159 modules)
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Missing variables (14):
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...
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LOCAL_REQUIRED_MODULES, by type:
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art_cc_library (2 modules)
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art_cc_library_static (4 modules)
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cc_library (28 modules)
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cc_library_shared (2 modules)
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LOCAL_SHARED_LIBRARIES, by type:
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art_cc_library (60 modules)
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....
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Extra variables (7):
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LOCAL_EXPORT_CFLAGS, by type:
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cc_library (4 modules)
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LOCAL_EXPORT_C_INCLUDE_DEPS, by type:
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art_cc_library (28 modules)
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...
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Diff variables: (18)
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LOCAL_EXPORT_C_INCLUDE_DEPS, by type:
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aidl_interface.go_android/soong/aidl.wrapLibraryFactory.func1__topDownMutatorModule (1721 modules)
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art_cc_library (12 modules)
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LOCAL_PREBUILT_MODULE_FILE, by type:
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apex.apexBundle (7 modules)
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apex.apexBundle.files (625 modules)
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...
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```
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## JSON Output ##
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It looks like this:
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```JSON
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{
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"RefPath": "<...>/out/soong/Android-aosp_arm64.mk",
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"OurPath": "<...>/out.mixed/soong/Android-aosp_arm64.mk",
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"MissingModules": [
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"adbd.com.android.adbd|cls:EXECUTABLES|target_arch:arm64",
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"android.hardware.common-V2-ndk.com.android.media.swcodec|cls:SHARED_LIBRARIES|target_arch:arm64",
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"android.hardware.graphics.allocator-V1-ndk.com.android.media.swcodec|cls:SHARED_LIBRARIES|target_arch:arm64",
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"android.hardware.graphics.allocator@2.0.com.android.media.swcodec|cls:SHARED_LIBRARIES|target_arch:arm64",
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...
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],
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"DiffModules": [
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{
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"Name": "_makenames|cls:EXECUTABLES|target_arch:arm64",
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"RefLocation": 137674,
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"OurLocation": 137673,
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"MissingVars": [ "LOCAL_SHARED_LIBRARIES", "LOCAL_STATIC_LIBRARIES" ],
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"DiffVars": [
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{
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"Name": "LOCAL_PREBUILT_MODULE_FILE",
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"MissingItems": [ "out/soong/.intermediates/external/libcap/_makenames/android_arm64_armv8-a/_makenames" ],
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"ExtraItems": [ "out/bazel-bin/external/libcap/_makenames" ]
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},
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{
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"Name": "LOCAL_SOONG_UNSTRIPPED_BINARY",
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"MissingItems": [ "out/soong/.intermediates/external/libcap/_makenames/android_arm64_armv8-a/unstripped/_makenames" ],
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"ExtraItems": [ "out/bazel-bin/external/libcap/_makenames_unstripped" ]
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}
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]
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},
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...
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]
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}
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```
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Use JSON query tool like [`jq`](https://github.com/stedolan/jq) to slice and dice it.
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