I am curious whether it is possible that an older version of ROOT (let’s say ROOT 6.28-00-patches) is available which can work on newer MacOS versions like MacOS 15.4? or even if there can be no such official version can somebody( ROOT experts) guide which files to modify so that the 6.28.00-patches works with newer MacOS’s
To give some context about why I asked about this. Let me describe my problem.
The last version that ships with -Dpythia6 flags to compile ROOT with Pythia6 was v6.28. Some Monte Carlo event generators like NuWro (GitHub - NuWro/nuwro: The main distribution of NuWro) which are heavily used in neutrino experiments like T2K and MINER$\nu$A uses Pythia6 for hadron showering. Since NuWro requires Pythia6 to be compiled with ROOT it is impossible to run NuWro MC generator on newer MacOS’s natively.
One way is that NuWro devs work on moving NuWro from Pythia6 to Pythia8 which is possible and hopefully already planned by NuWro devs but it will take some time.
Other way is that one can use some containers to run NuWro which is way above an understanding of an average users.
So it would be great if some ROOT developers/experts can help me create an older ROOT version compatible with newer MacOS’s.
maintaining ROOT on MacOS is unfortunately very time intensive, since there are frequent changes across OS and XCode versions. For this reason, the ROOT team is unable to support older versions of ROOT on MacOS, and I think you will have a very hard time if you tried it yourself.
I do remember, however, that other groups had the same problem, and out of this a standalone version of EGPythia6 was born:
Would this be a way to move to a more modern ROOT version while having Pythia6 compatibility?
Thanks for reaching out. I fully support what Stephan already said in his previous post. 6.28 is a cycle that started more than 2 years ago, and it’s last patch was released more than one year ago. In the meantime, two production releases, 6.30 and 6.32, were provided, as well as a development release, 6.34. Release 6.36.00 will be available at the end of May. If on the one hand we are forced to drop support of old releases for new macOS versions, we strive to maintain backwards (and forward) compatibility, breaking it only in exceptional cases.
I still would like to point out that we were very conservative, and decided to abandon Pythia 6 only recently even if “With the release of PYTHIA 8.3, there should be no reason for anyone to download and run any version of PYTHIA 6 or older.” (from Ancient (PYTHIA 6) - PYTHIA 8.3). Releases of the Pythia 6 cycle lost their status of “official current version” in 2007, and development was stopped in 2012.
Nevertheless, for your particular case, I hope you can leverage the nice solution Luke provided, and profit from a recent ROOT version and “his” Pythia 6 interface. If anything ROOT related pops up and you think you need support, you are warmly welcome to post on this forum and we’ll do our best to find a solution together with you.