Bug#1085405: Unresolvable dependency for libpetsc-real3.21-dev (Sid)

[Martin Diehl]

Hi Francesco,

thanks for the work and the detailed feedback.

Aa a maintainer of the Trilinos and PETSc packages for Arch Linux
(https://aur.archlinux.org/packages/petsc
and https://aur.archlinux.org/packages/trilinos), please allow me some
comments on the dependencies.

As far as I know, PETSc supports three packages from Trilinos: Kokkos,
Zoltan, and ML.
- Kokkos is to some extent independent of Trilinos
(https://kokkos.org/), there is also a separate Debian package:
https://packages.debian.org/sid/kokkos
- I'm not 100% sure how Zoltan is used within PETSc, but to me it seems
that it only needed as transitive dependency for MSTK, MOAB and ML
(optional).
- ML is deprecated and will be removed in the next Trilinos release.
PETSc build on Arch already fails with the current Trilinos version due
to all the deprecation warnings.

To me it seems that a dependency of PETSc on Trilinos makes no sense
anymore.
- Having ML available as preconditioner would be nice, but that will
become unsupported soon.
- Zoltan is of no use unless one the packages that support it are
dependencies of PETSc.
- Kokkos can be supported by having a dependency on the separate
package.

Since PETSc brings its own small "package manager", there are three
types of dependencies
- Actual (optional) PETSc dependencies (e.g. ML)
- Transitive dependencies
- "convenience dependencies": From my limited insights, it seems that
PETSc includes build instructions for packages that are not directly
connected to PETSc. I believe those are just added to have a consistent
stack for software that relies on PETSc and those libraries.

In my opinion, a PETSc package becomes more useful if PETSc is
configured with as many of those external libraries as possible. But
this needs of course extra maintenance efforts to make sure that
everything is compatible.

best regards,
Martin




On Sun, 2024-10-20 at 12:36 +0000, Francesco Ballarin wrote:
> Package: libpetsc-real3.21-dev
> Followup-For: Bug #1085405
> X-Debbugs-Cc: martin.diehl at kuleuven.be,
> francesco.ballarin at unicatt.it, dparsons at debian.org
> 
> Hi Martin,
> we expedited a fix by temporarily dropping trilinos, which itself is
> in need of
> a rebuild.
> Keep in mind that PETSc 3.21.6+dfsg1-2 still can't build correctly on
> all
> arches because some of them still need a openmpi 5 fix, but at the
> very least
> it did build correctly on some of the most common ones (amd64 and
> i386), which
> hopefully are the ones that you need for now.
> 
> We'll add trilinos back as soon as we can. If you application depends
> on it you
> may want to wait before trying again.
> 
> Cheers,
> Francesco

-- 
KU Leuven
Department of Computer Science
Department of Materials Engineering
Celestijnenlaan 200a
3001 Leuven, Belgium
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