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Re: Storing package metadata in ELF objects


On Sat, 2021-04-10 at 18:44 +0000, Zbigniew Jędrzejewski-Szmek wrote:
> [I'm forwarding the mail from Luca who is not subscribed to fedora-
> devel]
> On Sat, Apr 10, 2021 at 01:38:31PM +0100, Luca Boccassi wrote:
> Cross-posting to the mailing lists of a few relevant projects.

Note that in this version of the email the [N] references in your email
don't seem to point anywhere. I found an older variant of the same
email which contained:

[0] https://github.com/systemd/systemd/issues/18433
[1] https://systemd.io/COREDUMP_PACKAGE_METADATA/
[2] https://fedoraproject.org/wiki/Changes/Package_information_on_ELF_objects
[3] https://github.com/systemd/package-notes

> After an initial discussion [0], recently we have been working on a new
> specification [0] to encode rich package-level metadata inside ELF
> objects, so that it can be included automatically in generated coredump
> files. The prototype to parse this in systemd-coredump and store the
> information in systemd-journal is ready for testing and merged
> upstream. We are now seeking further comments/opinions/suggestions, as
> we have a few months before the next release and thus there's plenty of
> time to make incompatible changes to the format and implementation, if
> required.
> A proposal to use this by default for all packages built in Fedora 35
> has been submitted [1].
> The Fedora Wiki and the systemd.io document have more details, but to
> make a long story short, a new .notes.package section with a JSON
> payload will be included in ELF objects, encoding various package-
> build-time information like distro name&version, package
> name&version,
> etc.

Is there a list of default keys (and their canonical spelling, upper-
lower-Camel_Case, etc.)? If there is, could we have a "debuginfod" key
with as value an URL pointing to the debuginfod server URL where the
embedded build-id executable, debuginfo and sources can be found?

> To summarize from the discussion, the main reasons why we believe this
> is useful are as following:
> 1) minimal containers: the rpm database is not installed in the
> containers. The information about build-ids needs to be stored
> externally, so package name information is not available immediately,
> but only after offline processing. The new note doesn't depend on the
> rpm db in any way.
> 2) handling of a core from a container, where the container and host
> have different distros
> 3) self-built and external packages: unless a lot of care is taken to
> keep access to the debuginfo packages, this information may be lost.
> The new note is available even if the repository metadata gets lost.
> Users can easily provide equivalent information in a format that makes
> sense in their own environment. It should work even when rpms and debs
> and other formats are mixed, e.g. during container image creation.
> Other than in Fedora, we are already making the required code changes
> at Microsoft to use the same format&specification for internally-built
> binaries, and for tools that parse core files and logs.
> Tools for RPM and DEB (debhelper) integration are also available [3].
> > -- 
> > Kind regards,
> > Luca Boccassi

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