Bug#1112274: trilinos: FTBFS on arm64: collect2: fatal error: ld terminated with signal 6 [Aborted]

[Graham Inggs]

Hi Adrian

Thanks for digging into this!

On Mon, 24 Nov 2025 at 03:22, Adrian Bunk <bunk at debian.org> wrote:
> Already 16.1.0-1 did put mold in CXXFLAGS instead of LDFLAGS (using
> LDFLAGS seems to work), and this removed the -O2 resulting in building
> without optimization - which made the build faster.

So mold does not really speed things up?
Rather, the speed up is due to the accidental removal of the optimization flags?

> I would have a tendency to revert the mold change and instead do
> optimize=-lto, but whether the latter actually solves the problem
> for Ubuntu is unproven.

Do you mean reverting to the packaging state of 16.1.0-2?
If so, I am in favour.  The Ubuntu issues can be fixed in Ubuntu.

What about lowering optimization for riscv64?  Or just not building
there until the hardware is able to cope?

> I remembered that we also have a failure with mold on arm64 in deal.ii,
> and that is a variant of the same problem:
> Manually reverting [1] fixes the deal.ii/arm64 build with mold,
> but reverting mold usage might be the easiest fix.
> Using -DCMAKE_BUILD_TYPE=Release for not additionally building and
> shipping a half GB debug version of the library would be another option.

deal.ii has had ongoing problems with arm64 in Debian [2], which I
think predate the switch to mold.  I believe ftpmasters have removed
the arm64 binaries from testing at least three times in as many years.

Regards
Graham


[2] https://buildd.debian.org/status/logs.php?pkg=deal.ii&arch=arm64