[Petsc-trilinos-discussion] Scope and requirements

[Bartlett, Roscoe A.]

> "Bartlett, Roscoe A." <bartlettra at ornl.gov> writes:
> > ML gets built along with the rest of Trilinos as a TriBITS package in
> > VERA where PETSc is treated as a pre-built static TPL.  This is done
> > because changes are being made to Trilinos to drive CASL work but not
> > for PETSc.  Building PETSc downstream from Trilinos would mean
> > wrapping PETSc as a TriBITS package and we don't want to go there
> > unless we are forced to do so.
> 
> Sounds like a build system limitation.  Prometheus was a heavy user of
> PETSc, but --download-prometheus still set things up properly and
> registered it as a PC without needing client applications to add
> work-arounds.

 [Bartlett, Roscoe A.] Does the PETSc build system support 100% correct automatic incremental rebuilds when upstream dependencies for these downloaded packages change?  Does it do a 100% correct incremental rebuild when just a few files in the downloaded package change?  That is the problem.  Anyone can create a build system that does a one pass configure, build, and install from scratch.  The problem is supporting an efficient development process where bits and pieces are incrementally changing.  We take that for grated in a unified CMake system.

-Ross