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100 lines
3.1 KiB
ReStructuredText
100 lines
3.1 KiB
ReStructuredText
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.. _module-pw_android_toolchain:
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--------------------
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pw_android_toolchain
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--------------------
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Android toolchains differ from ``pw_toolchain`` in that the latter defines the
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tool names and paths at the lowest level, with customisation added at higher
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levels, while in ``pw_android_toolchain`` the tool names and paths are derived
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from build args and defaults so are defined last by calling
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``pw_generate_android_toolchain``.
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Setup
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=====
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You must first download and unpack a copy of the `Android NDK`_ and let Pigweed
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know where that is located using the ``pw_android_toolchain_NDK_PATH`` build
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arg.
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.. _Android NDK: https://developer.android.com/ndk
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You can set Pigweed build options using ``gn args out``.
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Toolchains
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==========
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``pw_android_toolchain`` provides GN toolchains that may be used to build
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Pigweed against an Android NDK. The following toolchains are defined:
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- arm_android_debug
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- arm_android_size_optimized
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- arm_android_speed_optimized
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- arm64_android_debug
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- arm64_android_size_optimized
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- arm64_android_speed_optimized
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- x64_android_debug
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- x64_android_size_optimized
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- x64_android_speed_optimized
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- x86_android_debug
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- x86_android_size_optimized
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- x86_android_speed_optimized
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.. note::
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The documentation for this module is currently incomplete.
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Defining Toolchains
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===================
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Defining Android NDK toolchains is similar to ``pw_toolchain`` except that
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instead of using ``generate_toolchain`` use ``pw_generate_android_toolchain``,
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and ensure that ``current_cpu`` is set in the toolchain ``defaults``.
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For example:
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.. code::
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import("//build_overrides/pigweed.gni")
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import("$dir_pw_android_toolchain/toolchains.gni")
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import("$dir_pw_android_toolchain/generate_toolchain.gni")
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my_target_scope = {
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# Use Pigweed's Android toolchain as a base.
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_toolchain_base = pw_toolchain_android.debug
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# Forward everything except the defaults scope from that toolchain.
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forward_variables_from(_toolchain_base, "*", [ "defaults" ])
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defaults = {
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# Forward everything from the base toolchain's defaults.
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forward_variables_from(_toolchain_base.defaults, "*")
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# Build for 64-bit AArch64 Android devices.
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current_cpu = "arm64"
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# Extend with custom build arguments for the target.
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pw_log_BACKEND = dir_pw_log_tokenized
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}
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}
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# Create the actual GN toolchain from the scope.
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pw_generate_android_toolchain("my_target") {
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forward_variables_from(my_target_scope, "*")
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}
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Since Android NDKs contain toolchains for all supported targets, as a
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convenience, ``pw_generate_android_toolchains`` does not require that
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``current_cpu`` is set. If any toolchain scope in the list does not set it, a
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toolchain for each supported target will be generated.
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.. code::
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# Generate arm_*, arm64_*, x64_*, and x86_* for each scope in the list.
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pw_generate_android_toolchains("target_toolchains) {
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toolchains = pw_toolchain_android_list
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}
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Customization
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-------------
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The Android SDK target version defaults to the value of the
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``pw_android_toolchain_API_LEVEL`` build arg. You can override this on global
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level, or on a per-toolchain level by setting ``api_level`` in the toolchain
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defaults.
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