build-ids, .debug_sup and other IDs

[Frank Ch. Eigler]

Hi -

> FWIW I looked a little at unifying these.  For example,
> bfdopncls.c:bfd_get_alt_debug_link_info could look at both the build-id
> and .debug_sup.
> 
> But, this seemed a bit weird.  What if both appear and they are
> different?  Then a single API isn't so great -- you want to check the ID
> corresponding to whatever was in the original file.

If both appear and are different, can we characterize the elf file as
malformed?  Does our current tooling produce such files?  If it's an
abnormality (requires special elf manipulation or whatever), we could
avoid bending backward for this case, and tune the tools to the
Normal.

> [...]
> I suppose a distro can ensure that the IDs are always equal.

Via debugedit for example?

> Maybe debuginfod could also just require this.

Or debuginfod could export the content under -both- IDs, if there were
two valid candidates, and just go with the flow.  Let the clients
choose which ID they prefer to look up by.


- FChE