[Software Issue] cross-compiling for Windows

[csylvain]

Platform

Linux

Platform Version

Ubuntu 24.04.3 LTS

FreeDV Version

dev-2026-02-14-259c

Steps to Reproduce

1. ensure Ubuntu prerequisites are installed
2. obtain llvm-mingw-20251216-ucrt-ubuntu-22.04-x86_64.tar.xz as shown in "Building for Windows" "Instructions" step #1
3. add LLVM path and use the cmake command as shown in "Building for Windows" "Instructions" step #5 [arch x86_64]

Expected Behavior

successfully compiled FreeDV-dev-2026-02-14-259c

Actual Behavior

[Error 2](make: *** [Makefile:156: all] Error 2)

during the compile, the following message in red text is emitted:

CMake Error at CMakeLists.txt:56 (message):
  Must provide -DPython3_ROOT_DIR when cross-compiling.

Additional Comments

No response

[tmiw]

I updated the README in #1232 to reflect the current build steps. Do those instructions work any better?

[csylvain]

• i found the updated Instructions
• from my homedir in WSL 2, i've installed WINE (Step #1)
• at Step #2 shouldn't i be installing Python3 before running pip?
• i'm guessing there's a missed command there

[csylvain]

i'm trying
WINEARCH=win64 DISPLAY= wine ./python-3.14.3-amd64.exe

[csylvain]

the Python3 install requires choosing "Customize Installation", skip "Optional Features" (hit Next), and then in "Advanced Options" check "Install Python 3.14 for all users", then hit Install

what the above does is put the Python executables where expected for the command that next runs pip.exe

[csylvain]

[sorry i'm doing this in stream-of-installation style]

Confirmed

commands should be:

export WINEPREFIX=`pwd`/wine-env
wget https://www.python.org/ftp/python/3.14.3/python-3.14.3-amd64.exe
WINEARCH=win64 DISPLAY= wine ./python-3.14.3-amd64.exe
DISPLAY= wine c:\\Program\ Files\\Python314\\Scripts\\pip.exe install numpy

when the Python 3.14 installation window appears, manual interaction is required:

choose "Customize Installation", skip "Optional Features" (hit Next), and then in "Advanced Options" check "Install Python 3.14 for all users", then hit Install

[csylvain]

CPack: - package: /home/csylvain/Software/freedv-gui/build_windows/FreeDV-2.3.0-dev-2026-02-15-259c-windows-x86_64.exe generated.
fingerscrossed .. looks like it works!

[tmiw]

[sorry i'm doing this in stream-of-installation style]

Confirmed

commands should be:

export WINEPREFIX=`pwd`/wine-env
wget https://www.python.org/ftp/python/3.14.3/python-3.14.3-amd64.exe
WINEARCH=win64 DISPLAY= wine ./python-3.14.3-amd64.exe
DISPLAY= wine c:\\Program\ Files\\Python314\\Scripts\\pip.exe install numpy

when the Python 3.14 installation window appears, manual interaction is required:

choose "Customize Installation", skip "Optional Features" (hit Next), and then in "Advanced Options" check "Install Python 3.14 for all users", then hit Install

Thanks, I thought that was in there but I guess it accidentally got deleted. The PR has now been updated and I'll merge shortly.