F26 System Wide Change: Separate Subpackage and Source Debuginfo

[Jan Kurik]

= System Wide Change: Separate Subpackage and Source Debuginfo =
https://fedoraproject.org/wiki/Changes/SubpackageAndSourceDebuginfo

Change owner(s):
* Mark Wielaard <mjw AT redhat DOT com>
* Neal Gompa <ngompa13 AT gmail DOT com>

Allow to install just the debuginfo for a subpackage and/or without
the source files. The debuginfo packages are huge because they contain
debuginfo and all sources for all subpackages. Being able to install
only the debuginfo for the subpackage that is installed reduces the
size that needs to be downloaded to analyze, trace, profile or debug a
program or core file. Some tracing and profiling tools don't need the
actual source files to provide stack traces or insert probes. So
installing the debugsources should be optional.

== Detailed Description ==
Currently both the .debug files and the source files of all
subpackages are included in a debuginfo package. This creates huge
debuginfo packages with a lot of data that might not be relevant to
the user/developer. By splitting out the sources (found under
/usr/src/debug) and the .debug file for the separate binaries of the
subpackages (under /usr/lib/debug) the amount of data a developer/user
needs to install to trace, profile or debug will be greatly reduced.

Other distributions (notably Suse) already split their debuginfo
packages this way. We will take those patches
(https://build.opensuse.org/package/view_file/openSUSE:Factory/rpm/debugsubpk...)
and integrate them into rpm upstream. This will involve two steps: -
https://taiga.fedorainfracloud.org/project/mjw-better-rpm-debuginfo-package-...
- https://taiga.fedorainfracloud.org/project/mjw-better-rpm-debuginfo-package-...

This depends on some of the cleanups introduced by the
ParallelInstallableDebuginfo change.

We can either make this work with the current dnf debuginfo-install
plugin by providing a meta package that matches the main-debuginfo
package which depends on all sub- and source-debuginfo packages. Or we
work with the dnf hackers to make dnf debuginfo-install work with
sub-debuginfo packages.

A couple of packages already have hand-written sub-debuginfo packages
(notably the kernel, glibc and gcc). We will work with those packages
to adopt the new standard approach.

Release engineering needs to be involved to see if any changes are
necessary for adding the sub-debuginfo/debugsources packages to the
repodata.

== Scope ==
* Proposal owners:
Patches against rpm upstream need to be integrated as outlined in the
Detailed Description.

* Other developers:
Upstream rpm and dnf maintainers have to review the proposed patches.
If accepted the package maintainers will have to decide whether those
patches can be backported for the next fedora release. Packages that
now split their debuginfo packages by hand might want to change their
package to adopt the new (standard) approach. Once all changes are in
a package debuginfo needs to be regenerated before it becomes
sub-package/source split.

* Release engineering:
Needs to be discussed. In theory no changes apart from those listed
above are needed. But release engineering might know whether any
changes are necessary for adding the sub-debuginfo/debugsources
packages to the repodata.

* List of deliverables:
N/A (Still Unknown)

* Policies and guidelines:
No changes, the debuginfo related rpm macros won't change. They will
just start producing sub-package debuginfo and debugsources packages
once all changes are in place.

* Trademark approval:
N/A (not needed for this Change)