Re: Need help with getting a package to build reproducibly on arm*

[Michael Hudson-Doyle <michael.hudson@canonical.com>]

On Sat, 9 Jan 2021 at 00:52, Michael Biebl <biebl@debian.org> wrote:

Am 07.01.21 um 22:39 schrieb Michael Hudson-Doyle:

> I'm hardly an expert in such things but it looks to me as if gcc is
> ordering things differently between the two builds:
>
> https://tests.reproducible-builds.org/debian/dbd/unstable/arm64/systemd_247.2-4.diffoscope.html#systemd-tests_---.---_arm--.deb---data.tar.xz---data.tar---.-usr-lib-systemd-tests-manual-test-udev---objdump---line-numbers---disassemble---demangle---reloc---no-show-raw-insn---section-.text---
>
> and all the other differences follow on from that. Unless systemd is using
> particularly strange compiler options,

cflags:
https://salsa.debian.org/systemd-team/systemd/-/blob/debian/master/meson.build#L343

linkflags:
https://salsa.debian.org/systemd-team/systemd/-/blob/debian/master/meson.build#L401

Those don't look particularly exotic to me.

We do build with LTO enabled.

I guess that could be the culprit. Would still be a gcc bug though AIUI.

Cheers,

mwh