Re: Storing package metadata in ELF objects

[Mark Wielaard <mark@klomp.org>]

Hi Guillem,

On Wed, 2021-05-19 at 02:19 +0200, Guillem Jover wrote:
> So this is where I guess I'm missing something. To be able to make
> sense of the coredumps there are two things that might end up being
> relevant, backtraces and source code. systemd-coredump might already
> emit a backtrace, and depending on the information provided it might
> be more or less useful. If one needs the actual debug symbols there's
> already some external querying/fetching required, and if distribution
> specific source code is required because many distributions patch
> upstream source, then even more querying/fetching will be required.
> 
> Which is why I'm not seeing why this standalone and isolated metadata
> would be of much help by itself. As in, the way I see it, either the
> information from systemd (w/o the extra metadata) is sufficient to
> track down bugs, or that querying/fetching would be needed anyway, at
> which point the metadata can be inferred too then?

Because without that metadata you cannot easily figure out where/how to
get the files needed to properly track down the bugs. But using that
metadata you can figure out where the debuginfod server is that can
provide all that information for the binaries/core files (or a distro
specific method if the distributor doesn't have a debuginfod server
yet).

> Oh, I was thinking about those mixed environments, full chroots or
> stripped down containers, from different vendors, but affecting Debian
> installations. What I'm also probably missing here is how does the
> metadata help for a third-party that is not expected to track/keep/upload
> debug symbols nor source packages into some repository, because otherwise
> I'm not seeing how they'd make use of the cores (if they are insufficient
> by themselves) to debug issues? I guess my question back would be what
> would they do with the metadata if they do not have the debug symbols
> nor the sources readily available? Also assuming of course they exercise
> good practices such as never reusing the same package-version-arch tuple
> for different builds, and similar. :)

Different builds will have different build-ids, so they can be kept
apart. But even if without the distributor having added debuginfod
meta-data and providing a server to fetch the extra symbols, debuginfo,
sources, the extra meta-data is useful to administrators. Just seeing
that crashes are associated with specific distro/version/packages helps
narrow down instabilities.

Cheers,

Mark