Introduction

Requirements

Crossenv requires Python 3.5 or higher (host and build). Significant work has gone into cross-compiling Python in newer versions, and many of the techniques needed to do the cross compilation properly are not available on older releases.

Crossenv currently only supports Linux build machines. Other operating systems may work, but they are untested and unsupported.

Vocabulary

There is no standard vocabulary for the pieces that go into cross-compiling, and different resources will often use contradictory terms. To prevent confusion we use the GNU terminology exclusively, which is used by Python itself.

Host	The machine you are building for. (Android, iOS, other embedded systems.)
Build	The machine you are building on. (Probably your desktop.)
Host-python	The compiled Python binary and libraries that run on Host
Build-python	The compiled Python binary and libraries that run on Build.
Cross-python	Build-python, configured specially to build packages that can be run with Host-python. This tool creates Cross-python.

How it works

Python makes a note of the compiler and compiler flags used when it was built. (This information can be viewed by running python3 -m sysconfig.) When distutils or setuptools attempts to create an extension module, they compile the extension using these recorded values along with reported information about the currently running system.

Cross-python creates a virtual environment that, when activated, tricks Build-Python into reporting all system information exactly as Host-python would. When done correctly, a side effect of this is that distutils and setuptools will cross-compile when building packages. All of the normal packaging machinery still works correctly, so dependencies, ABI tags, and so forth all work as expected.

Installation

Crossenv can be installed using pip (using build-python):

$ pip install crossenv