Putting in context :
The system is BIOS only based, has several HDDs with several distros but the initial HDD has the Manjaro boot with GRUB bootblock.
Recently installed and added OpenSuse Tumbleed to one of those extra HDDs with BtrFs .
caling update-grub shows :
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-6.6-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-6.6-x86_64.img
Found linux image: /boot/vmlinuz-6.1-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-6.1-x86_64.img
Found linux image: /boot/vmlinuz-5.15-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.15-x86_64.img
Warning: os-prober will be executed to detect other bootable partitions.
Its output will be used to detect bootable binaries on them and create new boot entries.
Found Windows 8 on /dev/sda1
Found antiX (23) on /dev/sdb1
Found Artix Linux (rolling) on /dev/sdb10
Found Void Linux on /dev/sdb11
Found AlmaLinux 9.2 (Turquoise Kodkod) on /dev/sdb12
Found openSUSE Tumbleweed on /dev/sdb13
Found Arch Linux (rolling) on /dev/sdb2
Found EndeavourOS Linux (rolling) on /dev/sdb3
Found MX 23.1 Libretto (23.1) on /dev/sdb5
Found Redcore Linux Hardened - Rolling.Boulder.Uphill (Rolling.Boulder.Uphill) on /dev/sdb6
Found Windows 10 on /dev/sdc1
Adding boot menu entry for UEFI Firmware Settings ...
Found memtest86+ image: /boot/memtest86+/memtest.bin
Although in the Manjaro GRUB menu the OpenSuse Tumbleed entry is missing …
How can I add that entry ?
The only hint I got ( I suppose ) is the btrFs filesystem .
Do I have to load any specific module in GRUB to activate it ?
Manjaro’s GRUB needs to be in charge, but if you installed another distro after Manjaro, then it’s that distro’s GRUB which is in charge. So you need to reinstall Manjaro’s GRUB to the MBR of your drive.
Boot up into Manjaro — or use the Manjaro USB and chroot into your Manjaro installation — and as root, issue the command…
Is Tumbleweed’s /boot on btrfs? If so, that could indeed be a problem, because the default Manjaro GRUB cannot handle anything other than ext4 due to the compression built into btrfs.
There is a grub-btrfs which can read btrfs, but it’s more geared toward booting btrfs snapshots.
Not the default GRUB, no. Unless you’re chain-loading and using Manjaro’s GRUB to boot the Tumbleweed GRUB. But it cannot boot any kernels residing on btrfs.
So what you can do is create a custom script under /etc/grub.d to load the partition boot sector of the Tumbleweed partition, which is presumably where you installed its own GRUB. And once you’ve created that script, you must then run sudo update-grub.
I asked about GRUB because Tumbleweed installed their own GRUB bootblock ( in their own HDD) , which I can boot if called directly in the BIOS “drive selection” …
Which leads me to the conclusion that TumbleWeed has their own “special” GRUB …
So, not much to do …
Thank you @Aragorn for the fast replies …
It should be fairly easy to create an entry for Tumbleweed. I see you have Windows installed as well. The methodology is the same for booting Tumbleweed’s GRUB as for booting Windows. You only need to point it at the correct partition.