Bug#1019957: grub2: should not be Multi-Arch: foreign?

[Samuel Thibault]

Source: grub2
Version: 2.02~beta2-22
Severity: normal

Hello,

In version 1.99~rc1-5, most grub packages were made Multi-Arch: foreign
with the following changelog: 

    Mark binary packages as Multi-Arch: foreign (for example, an amd64
    kernel installed on an i386 system could use the native architecture's
    GRUB).

But this looks incorrect to me, at least for some packages. The
case we have noticed is the grub-ieee1275-bin package in the case
of cross-building the debian installer. Since grub-ieee1275-bin
is multi-arch: foreign, the cross-build will be happy to use
grub-ieee1275-bin:amd64 as a dependency to provide the grub modules to
be included on the ISO image, which is wrong for e.g. cross-building a
powerpc ISO image.

AIUI, grub-ieee1275-bin should for instance rather be Multi-Arch: same,
so that the "build arch" version of grub-ieee1275-bin gets pulled for
building d-i, while still be co-installable along a host-installed
grub-ieee1275-bin package?

The same kind of remark probably applies to most grub arch-specific
packages.

The original discussion is on
https://salsa.debian.org/installer-team/debian-installer/-/merge_requests/24

Samuel

-- System Information:
Debian Release: bookworm/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable-debug'), (500, 'testing-debug'), (500, 'stable-security'), (500, 'stable-debug'), (500, 'proposed-updates-debug'), (500, 'proposed-updates'), (500, 'oldstable-proposed-updates'), (500, 'oldoldstable'), (500, 'buildd-unstable'), (500, 'unstable'), (500, 'stable'), (500, 'oldstable'), (1, 'experimental-debug'), (1, 'buildd-experimental'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, arm64

Kernel: Linux 5.19.0-1-amd64 (SMP w/8 CPU threads; PREEMPT)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled