Hi Adrian Thanks for digging into this!
On Mon, 24 Nov 2025 at 03:22, Adrian Bunk <[email protected]> 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
