ROOT package in Debian/Ubuntu

[guitargeek]

This subject often comes up in discussions, like just not in a discussion about rpath and soversion.

I therefore suggest to create a GitHub issue to discuss and work towards this goal, superseding the JIRA tickets where this was previously discussed:

• https://its.cern.ch/jira/browse/ROOT-6428
• https://its.cern.ch/jira/browse/ROOT-10878

We would definitely appreciate help here, in the best case by an external contributor who is already engaged with Debian packaging. Any PR to ROOT that goes in the direction of making it easier to generate .deb packages is highly welcome!

Debian 13 will be released this month I guess, but then we have the next Debian development cycle of about two years to make this happen.

FYI @stephanlachnit, maybe you can also give us some recommendations here, if you remember what is still missing concretely?

Also FYI @ellert and @olifre.

[ferdymercury]

Copy-pasting from the other thread: Maybe related / convenient for this:

https://its.cern.ch/jira/browse/ROOT-6428
https://its.cern.ch/jira/browse/ROOT-6446
https://its.cern.ch/jira/browse/ROOT-8588
https://its.cern.ch/jira/browse/ROOT-8589
https://its.cern.ch/jira/browse/ROOT-9403
https://its.cern.ch/jira/browse/ROOT-9443
https://its.cern.ch/jira/browse/ROOT-9481
https://its.cern.ch/jira/browse/ROOT-9569
https://its.cern.ch/jira/browse/ROOT-9758
https://its.cern.ch/jira/browse/ROOT-10021
https://its.cern.ch/jira/browse/ROOT-10151
https://its.cern.ch/jira/browse/ROOT-10415
https://its.cern.ch/jira/browse/ROOT-10697
https://its.cern.ch/jira/browse/ROOT-10756
https://its.cern.ch/jira/browse/ROOT-10878

• Specific mime-type for root files #6771
• Cannot build ROOT if some paths contain spaces #7311
• make MS corefonts optional #8357
• [Build system] ROOT installs its builtins directly into CMAKE_INSTALL_PREFIX. #8655
• Allow to use root as dependency using FetchContent #8923
• [cmake] Diagnose missing header (and include path) for externally built libraries. #9736
• Move ROOT settings files to config/root directory #10148
• Bug in ROOT library loading - .dot sub-directories #10704
• Please prefix generic library names with ROOT #10985
• .pcm files not deterministic/reproducible #11429
• Clean up and improve Cling's C++ header search #11612
• pcm files and static libraries don't go along .... #11852
• MIsbehaviour of ROOT with ASAN enabled: some tests are failing #14682
• Improve loading system fonts #16229
• Improve header file encapsulation #16327
• Many roottest tests fail if you build ROOT with -DNDEBUG in CXXFLAGS #16981
• Additional patch to Clangs CMake code is required in case LLVM was built with LLVM_LINK_LLVM_DYLIB=ON #18387
• Vc.pcm not found when running root after building with external Vc with runtime_cxxmodules ON #18949
• [cling] DlClose what DlLibMan has DlOpened in reverse order #19268
• Cling fails to build on Ubuntu 22.04 LTS cling#464 (comment)

[stephanlachnit]

For Debian 13 this is definitely too late. In general, there are two approaches:

• A quick and easy one: simply building a .deb that works and is distributed by CERN
• Building ROOT for official inclusion into Debian

In the past, I did some packaging work for ROOT which can be found here: https://salsa.debian.org/science-team/root/-/tree/debian/latest/debian. It is still based on 6.32 but should be easy to rebase, however it is mostly at the state of "it works" and not "is ready for inclusion in Debian".

If the goal is to provide an official Debian package, I can certainly help with this being a Debian Developer, but I have a TODO list that I cannot tackle on my own:

• Building ROOT using standard LLVM instead of a bundled copy - I'm not sure if build: Allow building ROOT using the Clang shared library #17698 is resolved or LLVM20 (Update ROOT and Cling to LLVM20 #19242) will allow for this, but it would definitely help.
• Using system packages (besides LLVM) - this is mostly done, all major dependencies are part of Debian, except for Pythia8, Apache Arrow, libzmq with draft API and OpenUI5. I think this is fine for now.
• Things like libCore in you default library folder are not gonna pass and neither is the workaround of moving them a private libdir and setting LD_LIBRARY_PATH or similar - so Please prefix generic library names with ROOT #10985 would need to be resolved.
• Fonts - embedding MS fonts is not an option for Debian packages, and even embedding libre fonts is not really an option. Fedora is carrying a patch for this (https://src.fedoraproject.org/rpms/root/blob/rawhide/f/root-fontconfig.patch) and I did open Improve loading system fonts #16229, but it did not really come to a conclusion.
• Copyright review - for inclusion in Debian packages have to go through copyright review and need to provide a file which describes the copyright for each file. Using Copyright (c) The ROOT authors like LLVM for all works but the source has to be checked embedded third-party files, which have to be either excluded (bundled dependencies, fonts) or properly annotated.

If the goal is to simply provide a .deb which users can download (or even a Debian repository which hosts those files), none of the things above need to be done, this already works and would mainly be a question of setting up the correct CI jobs.

[ferdymercury]

• Building ROOT using standard LLVM instead of a bundled copy

This is blocked at the moment by several patches on top of LLVM, including e.g. 1f4a6dc#diff-52e88643b56129074efbdfa65cbe691d5dcf67341d831ecb31b8662ae567594d
(#16410 (comment))

[amadio]

I was going to comment on libCore.so, but I see @stephanlachnit already mentioned it above. In https://its.cern.ch/jira/browse/ROOT-6428 the lack of XRootD is mentioned, but it's been officially packaged in Debian/Ubuntu since a while now, albeit with old versions, as per these OS policies.

If you just want to generate DEB packages, but not necessarily create all the necessary packaging infrastructure around ROOT to officially add it to Debian/Ubuntu, as suggested above, have a look at #6735 and 6f80a44.

[amadio]

For vanilla LLVM, see also https://bugs.gentoo.org/564302. I don't think it will be easy to make external LLVM work in an environment where other things like mesa also link to LLVM of a potentially different version, etc. See details in the Gentoo bug linked above. In Gentoo I gave up and now use builtin LLVM/Clang.

[stephanlachnit]

This is blocked at the moment by several patches on top of LLVM

Figured, I remember @hahnjo talking about more and more patches being upstreamed, so if this on the horizon for some future LLVM version that could be targeted for an inclusion in Debian. Building with system libLLVM worked in version 6.32 IIRC. In any case, there are enough arguments that ROOT requires a bundled LLVM (for now at least) so I think this should not be blocker.

[hahnjo]

Just to be 100% precise: we don't have patches for LLVM, "only" for Clang. However, this requires a specific (major) version of LLVM.

[cholmcc]

Hi Stephan,

Overall, I agree with your analysis of the situation. A few points.

For Debian 13 this is definitely too late. In general, there are two approaches:

In some sense, ROOT shouldn't try to meet a specific Debian release, but simply work to get ROOT into the distribution whether that be 13 or some later release.

• A quick and easy one: simply building a .deb that works and is distributed by CERN

Yeah, but that will surely disappoint many users, because, as you point out, it will not be easy to integrate. Also, I would not trust that CERN can actually do this in an agnostic fashion - it certainly hasn't in the past.

• Building ROOT for official inclusion into Debian

That's what I would go for (and did way back when - got really close, but then a lot of stuff happened).

• Building ROOT using standard LLVM instead of a bundled copy - I'm not sure if build: Allow building ROOT using the Clang shared library #17698 is resolved or LLVM20 (Update ROOT and Cling to LLVM20 #19242) will allow for this, but it would definitely help.

This is really really crucial. For the past 8 or so years, I've heard ROOT developers say - yeah, we are trying to get to stock LVM/Clang, and it will be there soon. That is kinda surprising, given that Cling is used as backend for some Jupyter kernels. AFAIR, there's a number of hooks that Cling need in Clang to work, and the idea was to get up-stream Clang to provide those hooks. Why that hasn't happened is odd.

And this then also points to another problem when packaging ROOT for Debian

• Using system packages (besides LLVM) - this is mostly done, all major dependencies are part of Debian, except for Pythia8, Apache Arrow, libzmq with draft API and OpenUI5. I think this is fine for now.

ROOT really needs to built cleanly against third-party libraries. That's a big thing in Debian. In that sense, it would make sense to take Cling out of ROOT and then link against it instead. That would also allow for Cling to be more easily integrated elsewhere.

• Things like libCore in you default library folder are not gonna pass and neither is the workaround of moving them a private libdir and setting LD_LIBRARY_PATH or similar - so Please prefix generic library names with ROOT #10985 would need to be resolved.

A private library directory, like /usr/lib/root could work, but is kinda deprecated.

• Copyright review - for inclusion in Debian packages have to go through copyright review and need to provide a file which describes the copyright for each file. Using Copyright (c) The ROOT authors like LLVM for all works but the source has to be checked embedded third-party files, which have to be either excluded (bundled dependencies, fonts) or properly annotated.

Way back when, I did that audit with Fons, and we got to a point where all code had been cleared for LGPL-compliance. Of course, new code has been added, and those parts needs to be audited.

If the goal is to simply provide a .deb which users can download (or even a Debian repository which hosts those files), none of the things above need to be done, this already works and would mainly be a question of setting up the correct CI jobs.

To really be accepted into Debian proper, ROOT needs to be split into several packages - see https://tracker.debian.org/pkg/root-system

Some historical information about my effort to get ROOT into Debian proper: https://wiki.debian.org/DebianScience/ROOT - it got so far as to testing :-)

Yours,
Christian

[stephanlachnit]

Just to be 100% precise: we don't have patches for LLVM, "only" for Clang. However, this requires a specific (major) version of LLVM.

Requiring a specific major LLVM version is not an issue, those are packaged separately in Debian anyway.

Some historical information about my effort to get ROOT into Debian proper

Ah so it was you who attempted this before!

In that sense, it would make sense to take Cling out of ROOT and then link against it instead.

Agreed, getting Cling in first and then building ROOT against that would be significantly easier.

To really be accepted into Debian proper, ROOT needs to be split into several packages

Yes, that is true - I haven't checked if there are automated way to annotate library versions, because otherwise this is a huge maintenance burden. It's probably enough to go with root-framework (binaries), root-framework-libs, root-framework-dev and python3-root.