Hi Xavier, I looked at your scripts to build Android but I failed to use them. Anyway, I'm not sure why these scripts have to be part of the CPython git repository.
Technically, is there a reason to put it aside the source code and Unix build scripts (configure/Makefile/setup)? Your https://github.com/python/cpython/pull/1629 only adds new files without touching existing files. I suggest to create new Git project. It may be in the python organization, or you may start with your GitHub account. Cross-compilation is hard, and I'm not sure that it's possible to build a single recipe for all Android API versions, all configuration, any set of libraries, etc. For Android, it seems like each developer might want a subtle different configuration which might not be easy to support. Having a separated Git project would allow people to contribute more easily, experiment their fork, etc. What do you think? I'm only talking about the proposed Android/ directory and https://github.com/python/cpython/pull/1629. Everything else is fine :-) Victor 2017-12-10 15:19 GMT+01:00 Xavier de Gaye <xdeg...@gmail.com>: > The following note is a proposal to add the support of the Android platform. > > The note is easier to read with clickable links at > https://github.com/xdegaye/cagibi/blob/master/doc/android_support.rst > > Motivations > =========== > > * Android is ubiquitous. > * This would be the first platform supported by Python that is > cross-compiled, > thanks to many contributors. > * Although the Android operating system is linux, it is different from most > linux platforms, for example it does not use GNU libc and runs SELinux in > enforcing mode. Therefore supporting this platform would make Python more > robust and also would allow testing it on arm 64-bit processors. > * Python running on Android is also a handheld calculator, a successor of > the > slide rule and the `HP 41`_. > > Current status > ============== > > * The Python test suite succeeds when run on Android emulators using > buildbot > strenuous settings with the following architectures on API 24: x86, > x86_64, > armv7 and arm64. > * The `Android build system`_ is described in another section. > * The `buildmaster-config PR 26`_ proposes to update ``master.cfg`` to > enable > buildbots to run a given Android API and architecture on the emulators. > * The Android emulator is actually ``qemu``, so the test suites for x86 and > x86_64 last about the same time as the test suite run natively when the > processor of the build system is of the x86 family. The test suites for > the > arm architectures last much longer: about 8 hours for arm64 and 10 hours > for > armv7 on a four years old laptop. > * The changes that have been made to achieve this status are listed in > `bpo-26865`_, the Android meta-issue. > * Given the cpu resources required to run the test suite on the arm > emulators, > it may be difficult to find a contributed buildbot worker. So it remains > to > find the hardware to run these buildbots. > > Proposal > ======== > > Support the Android platform on API 24 [1]_ for the x86_64, armv7 and arm64 > architectures built with NDK 14b. > > *API 24* > * API 21 is the first version to provide usable support for wide > characters > and where SELinux is run in enforcing mode. > > * API 22 introduces an annoying bug on the linker that prints something > like > this when python is started:: > > ``WARNING: linker: libpython3.6m.so.1.0: unused DT entry: type > 0x6ffffffe arg 0x14554``. > > The `termux`_ Android terminal emulator describes this problem at the > end > of its `termux-packages`_ gitlab page and has implemented a > ``termux-elf-cleaner`` tool to strip the useless entries from the ELF > header of executables. > > * API 24 is the first version where the `adb`_ shell is run on the > emulator > as a ``shell`` user instead of the ``root`` user previously, and the > first > version that supports arm64. > > *x86_64* > It seems that no handheld device exists using that architecture. It is > supported because the x86_64 Android emulator runs fast and therefore is a > good candidate as a buildbot worker. > > *NDK 14b* > This release of the NDK is the first one to use `Unified headers`_ fixing > numerous problems that had been fixed by updating the Python configure > script > until now (those changes have been reverted by now). > > Android idiosyncrasies > ====================== > > * The default shell is ``/system/bin/sh``. > * The file system layout is not a traditional unix layout, there is no > ``/tmp`` for example. Most directories have user restricted access, > ``/sdcard`` is mounted as ``noexec`` for example. > * The (java) applications are allocated a unix user id and a subdirectory on > ``/data/data``. > * SELinux is run in enforcing mode. > * Shared memory and semaphores are not supported. > * The default encoding is UTF-8. > > Android build system > ==================== > > The Android build system is implemented at `bpo-30386`_ with `PR 1629`_ and > is documented by its `README`_. It provides the following features: > > * To build a distribution for a device or an emulator with a given API level > and a given architecture. > * To start the emulator and > + install the distribution > + start a remote interactive shell > + or run remotely a python command > + or run remotely the buildbottest > * Run gdb on the python process that is running on the emulator with python > pretty-printing. > > The build system adds the ``Android/`` directory and the > ``configure-android`` > script to the root of the Python source directory on the master branch > without > modifying any other file. The build system can be installed, upgraded (i.e. > the > SDK and NDK) and run remotely, through ssh for example. > > The following external libraries, when they are configured in the build > system, > are downloaded from the internet and cross-compiled (only once, on the first > run of the build system) before the cross-compilation of the extension > modules: > > * ``ncurses`` > * ``readline`` > * ``sqlite`` > * ``libffi`` > * ``openssl``, the cross-compilation of openssl fails on x86_64 and arm64 > and > this step is skipped on those architectures. > > The following extension modules are disabled by adding them to the > ``*disabled*`` section of ``Modules/Setup``: > > * ``_uuid``, Android has no uuid/uuid.h header. > * ``grp`` some grp.h functions are not declared. > * ``_crypt``, Android does not have crypt.h. > * ``_ctypes`` on x86_64 where all long double tests fail (`bpo-32202`_) and > on > arm64 (see `bpo-32203`_). > > .. [1] On Wikipedia `Android version history`_ lists the correspondence > between > API level, commercial name and version for each release. It also provides > information on the global Android version distribution, see the two > charts > on top. > > .. _`README`: > https://github.com/xdegaye/cpython/blob/bpo-30386/Android/README.rst > .. _`bpo-26865`: https://bugs.python.org/issue26865 > .. _`bpo-30386`: https://bugs.python.org/issue30386 > .. _`bpo-32202`: https://bugs.python.org/issue32202 > .. _`bpo-32203`: https://bugs.python.org/issue32203 > .. _`PR 1629`: https://github.com/python/cpython/pull/1629 > .. _`buildmaster-config PR 26`: > https://github.com/python/buildmaster-config/pull/26 > .. _`Android version history`: > https://en.wikipedia.org/wiki/Android_version_history > .. _`termux`: https://termux.com/ > .. _`termux-packages`: https://gitlab.com/jbwhips883/termux-packages > .. _`adb`: https://developer.android.com/studio/command-line/adb.html > .. _`Unified headers`: > https://android.googlesource.com/platform/ndk.git/+/ndk-r14-release/docs/UnifiedHeaders.md > .. _`HP 41`: https://en.wikipedia.org/wiki/HP-41C > .. vim:filetype=rst:tw=78:ts=8:sts=2:sw=2:et: > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/victor.stinner%40gmail.com _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
