Build system does not work with Android NDK cross compiler

[truboxl]

The configure script operates on the basis that tests are compiled and run on build machine. config.h and config.mk are generated so that final blink binary works on the build machine.

This does not work for Android in which Android NDK are cross compilers. configure tests are cross compiled, erroneously run on build machine, failed and disabling all features.

Example log: https://github.com/termux/termux-packages/actions/runs/4768306570/jobs/8477478253#step:6:426

My past effort but abandoned:
https://github.com/truboxl/termux-packages/pull/88/files
https://github.com/truboxl/termux-packages/pull/91/files

Any chance to improve this situation?
Will manually intervene config.h and config.mk for now downstream...

[trungnt2910]

A possible approach is to include a config.h database. These are files copied from known platforms identified by their target triples.

When cross-compilation is detected, only feature flags (like --enable-vfs) are checked. Other #defines are copied from the database.

[tkchia]

Hello @truboxl,

Well, it looks like there are not that many programs that have good support for Canadian Cross setups, where the build, host, and target (or should we say "guest") platforms might all potentially be different.

To allow for {build platform} ≠ {host platform}, a possible fix might be to allow the configure script to accept an emulator name for host binaries. For now we have

  if compile -Werror -o "o/tool/config/${PROGRAM}" "tool/config/${PROGRAM}.c" &&
     run "o/tool/config/${RUNPROGRAM}"; then
    printf '%s\n' "${MESSAGE} yes" >&2
    if [ $# -gt 0 ]; then
      "$@"
    fi
    rc=0
  else
    printf '%s\n' "${MESSAGE} no" >&2
    rc=1
  fi

but maybe instead of running "o/tool/config/${RUNPROGRAM}" directly we could pass it to some Android emulator (?).

Yet another more simplistic alternative might be to skip the run step — i.e. if a program compiles then just assume the host platform supports the tested feature. I am not quite sure if this is a good idea though.

Thank you!

[jart]

Contributions welcome