diffoscope plans for the meeting

  • Reviewing these Post-Its:

Improve Platform Support

  • Portability to different platforms should improve. Some tools or used abstractions (like /dev/fd) might not be available.
  • Support for distro-specific or uncommon file formats can be improved.
  • The testsuite does not work everywhere (e.g. newer versions of software can break things, currently happens for Pascal). It should be more reliable.

Integrate debdiff & diffoscope

  • Should we implement a flag in debdiff to call diffoscope?
  • Should we replace debdiff with diffoscope completely? What features of debdiff would diffoscope still need?
  • It’s not really clear what the post-it author wants.

Parallel diffoscope (#842837)

  • Execution time is a serious issue, diffoscope should get faster.
  • It is not clear how well parallel Python is going to work for diffoscope due to the global interpreter lock.
  • Prior work by nomeata might exist somewhere.
  • We should have a hack session on parallel diffoscope.


  • https://try.diffoscope.org should be more well-known; it helpfully has a number of optional stuff for uncommon formats installed already.
  • Get the word out for non-reproducibility use cases like comparing across versions for updates or due diligence before deployment.
  • The bug tracking happens at the Debian bugtracker. That should be more visible. The website should have a “how to report bugs” section for people not familiar with the Debian bug tracker.

diffoscope Plugins

  • Should diffoscope have a plugin mechanism to support other file formats that authors may not want to upstream?

Output Format

  • Should diffoscope output markdown?
  • The output should be more accessible, e.g., for screen readers. Possibly to be implemented as a new output format.

What are Usability Issues with diffoscope?

  • Output limits could lead to spending a lot of processing time and then still not getting usable output. Should all arbitrary limits be removed?
  • Short command line options
  • Write documentation on how to implement support for a file format
  • Should diffoscope support excluding specific paths in archives to cut down runtime and ignore parts that are already known to differ?
  • Should diffoscope support disabling support for specific file formats?

Automatic Classification of Reproducibility Issues in diffoscope

  • Is this in scope for diffoscope? Should this be in a separate tool?
  • This would require knowledge of the format and lead to much more complex file format support.
  • This could be helpful in outputs, e.g. if an offset changes in an ELF binary you’d get lots of related changes that could otherwise be ignored

Action Items

  • lamby to open a bug for the output format accessibility
  • Bapt to submit his FreeBSD patches upstream
  • everyone to file tickets about portability problems

Session Proposals

  • Hacking parallel diffoscope
  • Porting diffoscope
  • diffoscope usability
  • Documenting, marketing and undebianizing diffoscope