Switching from RHEL 10 to Fedora 43 breaks boot loader due to missing grub.cfg

[HuijingHei]

Copy the issue from bootc bootc-dev/bootc#1734

When doing switches from RHEL 10 to Fedora 43, after reboot, check grub.cfg and bootuuid.cfg are in old vendor redhat, that will make the machine fails to boot a second time since grub.cfg cannot be found.

I think this is because bootupctl update only cares about EFI components like grub2 & shim, but do not update grub.cfg and bootuuid.cfg, although we have bootupctl adopt-and-update --with-static-config (PR#945), that will only update the 2 files in case ostree config --repo=/sysroot/ostree/repo get sysroot.bootloader is not set.

# mount /dev/nvme0n1p1 /boot/efi/
# ll -R /boot/efi/
/boot/efi/:
total 4
drwxr-xr-x. 5 root root 4096 Oct 17 13:14 EFI/

/boot/efi/EFI:
total 12
drwxr-xr-x. 2 root root 4096 Oct 17 13:14 BOOT/
drwxr-xr-x. 2 root root 4096 Oct 17 13:14 fedora/
drwxr-xr-x. 2 root root 4096 Oct 17 13:14 redhat/

/boot/efi/EFI/BOOT:
total 1016
-rwxr-xr-x. 1 root root 949424 Oct 17 13:14 BOOTX64.EFI
-rwxr-xr-x. 1 root root  87816 Oct 17 13:14 fbx64.efi

/boot/efi/EFI/fedora:
total 6644
-rwxr-xr-x. 1 root root     110 Oct 17 13:14 BOOTX64.CSV
-rwxr-xr-x. 1 root root 4046144 Oct 17 13:14 grubx64.efi
-rwxr-xr-x. 1 root root  848080 Oct 17 13:14 mmx64.efi
-rwxr-xr-x. 1 root root  949424 Oct 17 13:14 shim.efi
-rwxr-xr-x. 1 root root  949424 Oct 17 13:14 shimx64.efi

/boot/efi/EFI/redhat:
total 8
-rwxr-xr-x. 1 root root  53 Oct  7 19:15 bootuuid.cfg
-rwxr-xr-x. 1 root root 657 Oct  7 19:15 grub.cfg

[HuijingHei]

The bootloader-update.service is enabled on f43 (see https://fedoraproject.org/wiki/Changes/AutomaticBootloaderUpdatesBootc), and this only sync the EFI components shim & grub2 to /boot/efi, we should also copy grub.cfg and bootuuid.cfg to the new vendor dir fedora in this case. If I run bootupctl update on fedora-bootc:42, then the result will be the same as 43.

bootc switch quay.io/fedora/fedora-bootc:42

# reboot

[root@fedora ~]# bootc status
● Booted image: quay.io/fedora/fedora-bootc:42
        Digest: sha256:87c432058ac007ab6933dcbd8e29f1186ffbc5f75c020f25c1246606a2c3c040 (amd64)
       Version: 42.20251125.0 (2025-11-25T09:05:31Z)

  Rollback image: quay.io/centos-bootc/centos-bootc:stream10
          Digest: sha256:36d31bef67f59ab0b57e8041e8b5523f6f301838f18229f8154fbad4a73ea938 (amd64)
         Version: 10 (2025-11-26T22:28:38Z)

[root@fedora ~]# systemctl status bootloader-update
○ bootloader-update.service - Update bootloader on boot
     Loaded: loaded (/usr/lib/systemd/system/bootloader-update.service; disabled; preset: disabled)
    Drop-In: /usr/lib/systemd/system/service.d
             └─10-timeout-abort.conf
     Active: inactive (dead)
       Docs: https://github.com/coreos/bootupd

[root@fedora ~]# bootupctl update

[root@fedora ~]# ls -al /boot/efi/EFI/*
/boot/efi/EFI/BOOT:
total 1024
drwxr-xr-x. 2 root root   4096 Nov 27 09:09 .
drwxr-xr-x. 5 root root   4096 Nov 27 09:09 ..
-rwxr-xr-x. 1 root root 949424 Nov 27 09:09 BOOTX64.EFI
-rwxr-xr-x. 1 root root  87816 Nov 27 09:09 fbx64.efi

/boot/efi/EFI/centos:
total 16
drwxr-xr-x. 2 root root 4096 Nov 27 09:09 .
drwxr-xr-x. 5 root root 4096 Nov 27 09:09 ..
-rwxr-xr-x. 1 root root   53 Nov 27 08:53 bootuuid.cfg
-rwxr-xr-x. 1 root root  657 Nov 27 08:53 grub.cfg

/boot/efi/EFI/fedora:
total 6644
drwxr-xr-x. 2 root root    4096 Nov 27 09:09 .
drwxr-xr-x. 5 root root    4096 Nov 27 09:09 ..
-rwxr-xr-x. 1 root root     110 Nov 27 09:09 BOOTX64.CSV
-rwxr-xr-x. 1 root root 4037952 Nov 27 09:09 grubx64.efi
-rwxr-xr-x. 1 root root  848080 Nov 27 09:09 mmx64.efi
-rwxr-xr-x. 1 root root  949424 Nov 27 09:09 shim.efi
-rwxr-xr-x. 1 root root  949424 Nov 27 09:09 shimx64.efi