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Many moons ago, in the dark ages of Python, cross compiles were largely
unsupported. In these before-times, a patchset used by PtxDist [0] [1]
was adapted to help make cross compiles work.
The patchset did a number of things but mainly:
1) used a build-machine compatible python interpreter for certain
stages of the target Python build process
2) made adjustments to certain files to make decisions based on values
set in environment variables instead of the path of the executing
Python interpreter.
Since the path of the interpreter that was build machine compatible was
outside of the target build directory, the code that made assumptions
about the location of headers and library paths being relative to the
interpreter path needed to be adjusted, hence them being driven via
environment variables.
The patchset worked by replacing the executable path to be the sysroot
which included the python headers and libraries.
A number of issues regarding cross compilation [2] [3] [4] have since
been closed since the introduction of this patchset and cross builds
became much better supported starting in Python v3.3.1.
New logic primarily uses the _PYTHON_PROJECT_BASE env variable [5] [6].
When set properly, this drives a few things:
* flags a cross compile environment
* sysconfig.is_python_build = True which triggers:
* altered paths for finding the Makefile and config.h
* altered sysconfig.get_config_var("srcdir")
When migrating to Python 3.4, PtxDist reworked their patchset to use
the standard environment variables for their cross compiles [7].
The distutils module was a primary consumer of the custom variables from
the previous patchset, however, that module is deprecated and packages
cannot target it as of 09de823c.
Package builds and unit tests seem to work without using these variables
being set, implying they can likely be dropped. Packages that still use
distutils should be updated to reflect its removal in 3.12.
Once these custom variables are removed, the following Python3 patches
which leverage them can be dropped:
0004-Adjust-library-header-paths-for-cross-compilation
0009-Do-not-adjust-the-shebang-of-Python-scripts-for-cros
[0]: eef994411c
[1]: 6c79cb5ac3
[2]: https://github.com/python/cpython/issues/48004
[3]: https://github.com/python/cpython/issues/58538
[4]: https://github.com/python/cpython/issues/59689
[5]: 7e6c2e2cc4
[6]: 9731330d6f
[7]: 638a024500
Signed-off-by: Vincent Fazio <vfazio@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. The documentation can be found in docs/manual. You can generate a text document with 'make manual-text' and read output/docs/manual/manual.text. Online documentation can be found at http://buildroot.org/docs.html To build and use the buildroot stuff, do the following: 1) run 'make menuconfig' 2) select the target architecture and the packages you wish to compile 3) run 'make' 4) wait while it compiles 5) find the kernel, bootloader, root filesystem, etc. in output/images You do not need to be root to build or run buildroot. Have fun! Buildroot comes with a basic configuration for a number of boards. Run 'make list-defconfigs' to view the list of provided configurations. Please feed suggestions, bug reports, insults, and bribes back to the buildroot mailing list: buildroot@buildroot.org You can also find us on #buildroot on OFTC IRC. If you would like to contribute patches, please read https://buildroot.org/manual.html#submitting-patches