NoMorePython2

No More Python 2!

Problem Statement

Python 2 is in maintenance mode and everyone should shift to Python 3. We've made the move in OpenEmbedded Core so that core-image-sato doesn't pull in Python 2, but Python 2 is still needed during the build.

There are two ways in which Python 2 is needed:

1. Use of /usr/bin/python on the host
2. Explicit dependency on python-native

Goal

To be able to build first core-image-sato and then world of OpenEmbedded Core without Python 2 being present on the host, or being built via python-native.

Method

To find implicit dependencies on the build host having Python 2, one option is to just remove Python 2 from your build host. Whilst this works, unless you're building inside a container this might not be feasible. The next best thing is to make the binary not executable briefly for the test builds. Sadly you can't remove Python 2 from HOSTTOOLS as several upstreams will explicitly poke around /usr/bin looking for a Python to run.

To find recipes that depend on python-native then simply build an image/world/whatever with -g and search the resulting task-depends.dot. For example, building core-image-sato for intel-corei7-64 results in:

"core-image-sato.do_build" -> "bmap-tools-native.do_build"
"bmap-tools-native.do_prepare_recipe_sysroot" -> "python-native.do_populate_sysroot"

So, an image depends on bmap-tools-native which depends on Python 2.

Patches, from ready to submit to utter hacks, are being collected in poky-contrib:ross/nopy2.

Status

Patches Ready

• ca-certificates
• libsoup
• grub
• pseudo
• ninja

To Review

• xcb-proto (do all callers use py3)
• texinfo-dummy-native (does it still work)

Broken

• python3-pycairo (appears to just need a Waf update)
  • Waf uses Python 2 by default
  • Add waf-native to oe-core
  • Extend waf class to invoke waf-native using Python 3
  • Use waf class in python3-pycairo
• webkitgtk
• ovmf
• eglinfo-x11 eglinfo-fb (same as python3-pycairo, uses Waf)
• bmaptool

Needs Python 2, actively refuses to use Python 3

• apr
• qemu