[PATCH] D53736: [BTF] Add BTF DebugInfo

Mon Nov 26 08:51:04 PST 2018

ast added a comment.

In D53736#1307616 <https://reviews.llvm.org/D53736#1307616>, @MaskRay wrote:

> I find that there hasn't been actual discussion on the mailing list

at this point we're no longer looking for feedback on the format itself.
Since BTF already ships as part of linux kernel we cannot change the core format anymore.
Only future BTF extensions are up for discussion.
If you're interested in participating I suggest to subscribe to netdev mailing list.
That's where any BTF/BPF discussions were and will be happening.

> BTF type descriptors does not seem to improve much compared with DWARF, but the deduplicated result is impressive (137x reduction).

BTF is tightly coupled with BPF ISA. It's not a traditional debug format like dwarf and not like Solari's CTF.
Linux kernel loads the BTF description and verifies it, since it's about to start using BTF for _safety_ decisions.
It's not debug-info only format.

The latest version of pahole already can convert dwarf to BTF.
But we need tight integration of BTF with llvm's BPF backend to be able to provide func_info and line_info directly into .BTF and .BTF.ext sections
(in this patch set) and for symbolic struct field references (future work).

We don't expect BTF to be used with anything but BPF ISA.

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D53736/new/

https://reviews.llvm.org/D53736