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I'm running a triple boot Windows/Ubuntu/Fedora (I just installed Fedora) and unfortunately my grub doesn't find Fedora. I tried a few solutions online (update the grub, os-prober...) but nothing has worked.

On my understanding I have to add an entry to the file 40_custom, but I'm not sure what to enter exactly. The location of my Fedora is /dev/dm-0, UUID 8d366751-d6fb-4ada-a807-c090ae6ba61e.

The Fedora is on vfat and it's the latest (36), Ubuntu is 22.04

Could anyone help me?

thanks!

Kevin J
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  • You haven't provided any release details; nor what file-systems are involved; as some fs (eg. btrfs) are harder to handle and thus can be skipped in update-grub. – guiverc Jun 11 '22 at 05:47
  • oh sorry! So the Fedora is on vfat and it's the latest (36), Ubuntu is 22.04. – Kevin J Jun 11 '22 at 05:53
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    You may need drivers in Ubuntu as Fedora is using different configuration. And full install cannot be in vfat, but that may be UEFI boot files? Best to see details: Please copy & paste the pastebin link to the Bootinfo summary report ( do not post report), do not run the auto fix till reviewed.Lets see details, use ppa version with your USB installer (2nd option) or any working install, not Boot-Repair ISO https://help.ubuntu.com/community/Boot-Repair &
    https://sourceforge.net/p/boot-repair/home/Home/     – oldfred Jun 11 '22 at 18:30
  • @oldfred here is the report: https://pastebin.com/KxMaHSmZ

    thank you!

     – Kevin J Jun 12 '22 at 00:27
  • Do you have btrfs drivers in Ubuntu & then mount Fedora partition before running os-prober? Of use a grub configfile in 40_custom to load the Fedora ESP entry,/efi/fedora/grub.cfg, from the Ubuntu grub, so Fedora boots directly from its ESP entry. Similar to this but with your ESP's UUID (or label) and /efi/fedora/grub.cfg as grub to load. https://askubuntu.com/questions/1205982/how-make-external-usb-disk-bootable-for-bios-and-uefi or https://askubuntu.com/questions/344125/how-to-add-a-grub2-menu-entry-for-booting-installed-ubuntu-on-a-usb-drive/344359#344359 – oldfred Jun 12 '22 at 04:04
  • thanks @oldfred !
    • I have installed the btrfs drivers and made sure the Fedora partition was mounted but it didn't change the os-probe result
    • I have edited the 40_custom like this:

    menuentry "Fedora" { set root=(hd1,1) linux /boot/vmlinuz root=/dev/dm-0 ro quiet splash initrd /efi/fedora/grub.cfg } So now I have the Fedora entry in the Grub, but it says it cannot find /boot/vmlinuz and I need to load the kernel first. I'm guessing I just need to change that path to something else?

     – Kevin J Jun 12 '22 at 05:58
  • If using a boot stanza, it is past the grub.cfg in /efi/fedora, but using grub in your install. You probably can just copy Fedora's boot stanza into Ubuntu's 40_custom. That would give you the correct entry. Only a three line (or even one line) configfile entry is required to load the /efi/fedora/grub.cfg. Not sure how grub sees nvme drives, or which is nvme1n1p1 for ESP. Could just configfile (hd1,1)/efi/fedora/grub.cfg Go to grub command line when booting at grub menu & do ls & then ls /efi to see which drive & partition is correct. – oldfred Jun 12 '22 at 14:23

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