Narrow libbcc dependency from llvm-dev to just libllvm

[bobrik]

It works with list libllvm, so no need to pull in the whole thing, which is 600MiB worth of packages.

[bobrik]

@shunghsiyu, what exactly broke for you prior to #4921?

[shunghsiyu]

It works with list libllvm, so no need to pull in the whole thing, which is 600MiB worth of packages.
@shunghsiyu, what exactly broke for you prior to #4921?

The problem for me is that using bcc header files (packaged as bcc-devel on RPM systems) requires llvm-devel to be on installed as well since 6f11bf7, otherwise compilation will fail. This is not a theoretical issue but an actual one that we saw with Sysinternals/ProcMon-for-Linux.

debian/control does not have a separate package to host the bcc header files so I ended up placing such requirement on the main bcc package, which is admittedly not ideal.

[shunghsiyu]

From a packaging point of view I'd much prefer we revert 6f11bf7 to keep the dependency at a minimum.

That said I only know two users of bcc-devel: one is Sysinternals/ProcMon-for-Linux mentioned above, and the other is bpftrace/bpftrace. bpftrace already pulls llvm-devel itself anyway, while ProcMon-for-Linux doesn't get packaged everywhere; so this is perhaps a bit of bikeshedding.

@chantra what do you think?

[chantra]

On Sun, May 19, 2024 at 11:02 PM Shung-Hsi Yu ***@***.***> wrote: From a packaging point of view I'd much prefer we revert 6f11bf7 <6f11bf7> to keep the dependency at a minimum.

For packaging, this should only be a build dependency right: https://www.debian.org/doc/debian-policy/ch-relationships.html ? The package itself has a pretty minimal footprint (26kb on Ubuntu per https://packages.ubuntu.com/noble/llvm-dev). Probably this pulls more deps, but only on the build machine. Quickly checking the issue, I think moving llvm-dev to a “Build-Depends” would solve the problem for machines where bcc gets installed. Would that be a good enough middle ground? That said I only know two users of bcc-devel: one is

…

Sysinternals/ProcMon-for-Linux <https://github.com/Sysinternals/ProcMon-for-Linux> mentioned above, and the other is bpftrace/bpftrace <https://github.com/bpftrace/bpftrace>. bpftrace already pulls llvm-devel anyway, while ProcMon-for-Linux doesn't get packaged everywhere; so this is perhaps a bit of bikeshedding. @chantra <https://github.com/chantra> what do you think? — Reply to this email directly, view it on GitHub <#4997 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAF77DROQGITXS5HX7OYKTZDGGWXAVCNFSM6AAAAABHPIRQ7CVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDCMJZG4ZDONRQGA> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[chantra]

If bcc-devel requires llvm-devel, I suppose the problem is because we pull llvm-config.h in bcc_module.h which is public? Moving llvm-config.h to private only headers should do the job.

Can you list the public headers and we can work on moving this include out of the way.

[shunghsiyu]

For packaging, this should only be a build dependency right

Not sure about Debian, but on the RPM side, even though llvm-devel is a build-time dependency for ProcMon-for-Linux, it should be listed as a runtime dependency for bcc-devel to get it transitively installed; otherwise llvm-devel do not get installed along with bcc-devel.

The follow graph depicts the dependency chain:

ProMon (build-time dependency with "BuildRequires: bcc-devel") --> bcc-devel (runtime dependency with "Requires: llvm-devel") --> llvm-devel

[shunghsiyu]

If bcc-devel requires llvm-devel, I suppose the problem is because we pull llvm-config.h in bcc_module.h which is public? Moving llvm-config.h to private only headers should do the job.

I think that will work

Can you list the public headers and we can work on moving this include out of the way.

The public headers I founds are:

• BPF.h
• BPFTable.h
• bcc_common.h
• bcc_elf.h
• bcc_exception.h
• bcc_proc.h
• bcc_syms.h
• bcc_usdt.h
• bcc_version.h
• bpf_module.h
• file_desc.h
• libbpf.h
• perf_reader.h
• table_desc.h
• table_storage.h

So bpf_module.h should be the one that need modification.