Re: Does gdb debuginfod download libc etc.?

[Mark Wielaard <mark@klomp.org>]

Hi Paul,

On Mon, Mar 09, 2026 at 05:19:44PM -0400, Paul Smith via Gdb wrote:
> (Most of) my core files are generated by the Google coredumper library,
> not by the Linux kernel, and I guess they don't have this note section.
> 
> It appears that this note section isn't actually required in order for
> us to access the build ID values (after all, elfutils does it), but
> this function gives up if the section doesn't exist.
> 
> I can look into how to force my cores to have this section, but I'd
> really like to teach GDB how to handle core files without it, since I
> have a lot of them and will likely continue to get them for some time
> even if I do manage to make this change to new releases.

Not sure this helps, since I know very little about gdb/bfd, but the
way elfutils gets at the build-id is to represent each core PT_LOAD as
an Elf and then tries to read the NOTEs either through the section
headers or the program headers. See
https://sourceware.org/cgit/elfutils/tree/libdwelf/dwelf_elf_gnu_build_id.c

This is somewhat simpler in elfutils because it just deals with ELF
files and doesn't care about other binary formats. Maybe there is a
simple mapping from bfd to elf sections/segements to do the same?

Cheers,

Mark