How to dual boot Debian 12 with existing another Linux installation by manual partitioning?

[Skywalker71]

Yes. Debian use ext4 filesystem. But if you can manage by writing a proper step by step guide, it will be very helpful. I think putting Gentoo and Debian in the bootloader will be same for Fedora and Debian.
I will wait for your return.

[kovacslt (László Kovács)]

@Skywalker71

It did not recognise the WiFi. So, I couldn’t connect to the internet.

This still worries me.
Otherwise the USB worked as expected?

[kovacslt (László Kovács)]

Thank Sheila!

Without seeing the output of parted -l I would never guessed btrfs to be in the game…

And on your link to Debian wiki:

So far, grub auto OS detection is flaky for btrfs,

explains why Fedora wasn’t present in the menu.
I wasn’t aware of this btrfs thing, as I told I have zero expereience with Fedora…

[Sheila_Flanagan]

@ihasama

My work laptop has btrfs filesystem with Gentoo which controls the grub.

That is the key. As I said earlier, having a btrfs OS control grub by installing it “after” MX Linux, I had no issues as it incorporated other installs into its grub. It is when you try to install the non-btrfs after the btrfs OS and have it control grub that issues arise.

If @Skywalker71 has already been using Fedora and does not want to install it again, we have to use a work around in order for Debian to show Fedora in its grub menu.

@Sheila_Flanagan

How to enable os-prober to detect btrfs installs with "/"-root on subvolumes...

For BTRFS installtions, where system root "/" files system is located on a btrfs-subvolume,
GRUB through update-grub ( => grub-mkconfig ) does have difficulties to generate
a GRUB menu entry for those other installations found on another partition.
update-grub is using os-prober. And os-prober does not have an indication
what subvolume "/"-root filesystem is located on.

In order to "help" os-prober to detect the GRUB-installtion on such btrfs-install
with subvolumes, some symlinks needs to be added to the "top id=5" subvolume.

So I had to add those symlinks and copy a folder from @/boot on that subvolume to the EFI partition of MX Linux. Then MX gained back control of grub and added the entry in grub menu for Garuda OS.

Sheila

[ihasama]

Ok, now at the office. My partition layout is this:

The Debian is ext4 and I used Gparted to making the partition. My Debian os has only tty, no GUI so you should make big enough partition for it (at least 50GB would be fine). When you’re installing Debian don’t let it install automatically to disk because it would then use the entire disk for Debian. Choose “something else”. There choose the partition you made with Gparted and use it as root. If the installer won’t let you go on without boot or efi partition you need to make one (just 512MiB fat32) and choose the small fat partition for boot.

After installation when the Debian reboots press tab/esc/F2/F10/F12 which one depends on your hardware and you get to the bios. Choose from there the Fedora boot partition (propably nvmeon1p1) and boot from there.

On Fedora remove the Debian boot partition with Gparted and check that your boot flag is as my on the picture (nvme0n1p1, fat32, /efi EFI and flags boot, esp). Then update-grub (or preferably sudo grub-mkconfig -o /boot/grub/grub.cfg) and follow the output of the update. It should say something like “using OS-prober to find other systems” and find your Debian and add it to the boot menu. At this point you should have a boot menu with both OSes.

If you don’t get the os-prober working let us know! If it’s not working / find Debian theres something wrong and probably just need to modify one config file.

[nevj (Neville Jackson)]

@ihasama

My work laptop has btrfs filesystem with Gentoo which controls the grub. Second os is Debian

I bet you cant make Debian the grub controlling distro, unless you have a separate /boot partition in Gentoo which is ext4

[nevj (Neville Jackson)]

@Skywalker71

Now I demand a spoonfeeding… regarding this Fedora Debian dual booting obviously.

I dont think I know enough about Fedora to do that.

I think what you have to do is reinstall Fedora and make its /boot filesystem a separate partition with an ext4 filesystem., and leave its root partition as btrfs.

The reason for that is that grub ( or maybe os-prober) can not read a btrfs filesystem, so it cant access the grub.cfg file in Fedora if it is all on one btrfs partition . The workaround is to make /boot a separate partition and make it ext4.

Then , if you get that right, following my original steps should work.

But, I cant guarantee anything, because I dont understand Fedora.

[ihasama]

@nevj

I bet you cant make Debian the grub controlling distro, unless you have a separate /boot partition in Gentoo which is ext4

and I don’t want to. I have efi partition which is fat32 and boot is on Gentoo, btrfs.

pete@gentoo ~ $ sudo parted -l
Model: KINGSTON SNV2S500G (nvme)
Disk /dev/nvme0n1: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start   End     Size    Type     File system     Flags
 1      1049kB  2149MB  2147MB  primary  fat32           boot, esp
 4      2149MB  10.5GB  8338MB  primary  linux-swap(v1)  swap
 2      10.5GB  416GB   405GB   primary  btrfs
 3      416GB   500GB   84.2GB  primary  ext4

pete@gentoo / $ ls /
bin  boot  deja-dup  dev  dots  efi  etc  home  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  sys  temp  tmp  usr  var  work

pete@gentoo ~ $ ls -la /boot/
total 400404
drwxr-xr-x 1 root root      990 Oct 29 15:37 .
drwxr-xr-x 1 root root      302 Oct 11 10:15 ..
-rw-r--r-- 1 root root        0 Jun 16 14:28 .keep
-rw-r--r-- 1 root root  9413378 Oct  4 07:39 System.map-6.6.51-gentoo-dist
-rw-r--r-- 1 root root  9491377 Oct 26 12:43 System.map-6.6.57-gentoo-dist
-rw-r--r-- 1 root root  9491377 Oct 25 09:56 System.map-6.6.57-gentoo-dist.old
-rw-r--r-- 1 root root  9491563 Oct 29 15:37 System.map-6.6.58-gentoo-dist
-rw-r--r-- 1 root root    77312 Oct 29 15:32 amd-uc.img
-rw-r--r-- 1 root root   266814 Oct  4 07:39 config-6.6.51-gentoo-dist
-rw-r--r-- 1 root root   267709 Oct 26 12:43 config-6.6.57-gentoo-dist
-rw-r--r-- 1 root root   267709 Oct 25 09:56 config-6.6.57-gentoo-dist.old
-rw-r--r-- 1 root root   267712 Oct 29 15:37 config-6.6.58-gentoo-dist
drwxr-xr-x 1 root root      130 Oct 31 13:34 grub
-rw-r--r-- 1 root root 68048193 Oct  4 07:39 initramfs-6.6.51-gentoo-dist.img
-rw-r--r-- 1 root root 72263713 Oct 26 12:43 initramfs-6.6.57-gentoo-dist.img
-rw-r--r-- 1 root root 72263618 Oct 25 09:56 initramfs-6.6.57-gentoo-dist.img.old
-rw-r--r-- 1 root root 72286059 Oct 29 15:37 initramfs-6.6.58-gentoo-dist.img
-rw-r--r-- 1 root root 16665600 Oct  4 07:43 intel-uc.img
-rw-r--r-- 1 root root 15715312 Oct  4 07:39 vmlinuz-6.6.51-gentoo-dist
-rw-r--r-- 1 root root 17894384 Oct 26 12:43 vmlinuz-6.6.57-gentoo-dist
-rw-r--r-- 1 root root 17894384 Oct 25 09:56 vmlinuz-6.6.57-gentoo-dist.old
-rw-r--r-- 1 root root 17894384 Oct 29 15:37 vmlinuz-6.6.58-gentoo-dist

[nevj (Neville Jackson)]

@ihasama

I don’t want to. I have efi partition which is fat32 and boot is on Gentoo, btrfs

I was just making a point… I know you dont want that.

Do you use grub to boot Gentoo?
I am wondering how grub could read its grub.cfg file buried inside your btrfs filesystem?

https://forums.linuxmint.com/viewtopic.php?t=315464

File System - GRUB2 support for BTRFS

[ihasama]

@nevj

I was just making a point… I know you dont want that.

Do you use grub to boot Gentoo?
I am wondering how grub could read its grub.cfg file buried inside your btrfs filesystem?

Btrfs and GRUB Solved - Linux Mint Forums

yes, I know I use grub, I have a EFI stub on my boot and everything works. I didn’t even know grub doesn’t work with btrfs. I just changed my SSD and decided to format it as btrfs a while ago and dd’ed the old SSD to the new one and all is working.

edit: here’s the grub info on my gentoo:

sys-boot/grub-2.12-r5::gentoo was built with the following:
USE=“device-mapper fonts mount nls sdl themes truetype -doc -efiemu -libzfs -secureboot (-test) -verify-sig” ABI_X86=“(64)” GRUB_PLATFORMS=“efi-64 -coreboot -efi-32 -emu -ieee1275 (-loongson) -multiboot -pc -qemu (-qemu-mips) -uboot -xen -xen-32 -xen-pvh”
CFLAGS=“”
LDFLAGS=“”

[nevj (Neville Jackson)]

@ihasama

. I just changed my SSD and decided to format it as btrfs a while ago and dd’ed the old SSD to the new one and all is working.

Have you tried update-grub since you changed to btrfs?

To be honest, I am not sure whether grub works properly with Btrfs or not. Reports are conflicting.

Dont panic. You can always use UEFI boot.

[ihasama]

Yes, with sudo grub-mkconfig -o /boot/grub/grub.cfg

[Skywalker71]

Only the USB 3 ports. USB 2 ports were out. But now if you ask me to do anything in Debian, I can’t because as I have mentioned earlier, after the mess, I wiped the drive completely deleting the partitions and now I have installed Fedora 41. It’s really nice. The first thing I noticed that the internet is faster than in Fedora 40.

[kovacslt (László Kovács)]

I think you can install Davinci on Fedora?
Then install ocl-icd,

ocl-icd - Fedora Packages

That seems to be the Fedora equivalent of mesa-opencl-icd.
Someone with Fedora expertise hopefully can confirm this.

Install Davinci on Fedora, then check your users membership.
Probably needs to be in groups ‘video’ and ‘render’.
If you aren’t member of those group, make it…
Log-out, log-in to take effect the changed mebership.
Start Davinci…
…fingers crossed…

[Skywalker71]

What if, I install Debian 12 first and then Fedora? What might be the outcome?

[Sheila_Flanagan]

@nevj

I bet you cant make Debian the grub controlling distro, unless you have a separate /boot partition in Gentoo which is ext4

That’s what I was saying. As long as I was okay with Garuda controlling grub, no issue. I installed Garuda AFTER MX, it took control and it found MX to add to its grub menu. It is the reverse that does not work.

Sheila

[Sheila_Flanagan]

No, it is the issue of needing to install the btrfs after the other Linux. Fedora is capable of finding other Linux OS on the drives. But other Linux (like Debian) cannot gind Fedora due to use of subvolumes, without modifications.

I did not figure you wanted to reinstall Fedora, otherwise I would say, start over, install Debian and then install Fedora and let it control grub. At least that worked for me with MX & Garuda.

Sheila

[ihasama]

I tried if Debian could find Gentoo and it found it. From btrfs. Maybe grub had been updated to work with btrfs also.

and here’s the same on Gentoo. Only difference seems to be how Debian mounts nvme0n1p1 to /boot/efi and Gentoo /efi

[ihasama]

@Sheila_Flanagan

But other Linux (like Debian) cannot gind Fedora due to use of subvolumes, without modifications

that’s true, I tried that and it didn’t find the snapshots but did find the gentoo os from btrfs

[nevj (Neville Jackson)]

@ihasama

Yes, with sudo grub-mkconfig -o /boot/grub/grub.cfg

And did grub see the changes?.. can you see them in the edit menu?