This is a simple guide and it does not remove grub.
This is on a clean install of Fedora 37 beta, but it works the same on 36. An automatic partition has been used.
Current disk layout:
[otheos@brahe ~]$ lsblk -o name,fstype,uuid,mountpoints
NAME FSTYPE UUID MOUNTPOINTS
sda
├─sda1 vfat EDD2-2B6B /boot/efi
├─sda2 ext4 e7a200bb-2c26-4fb4-b120-764fda7a5378 /boot
└─sda3 btrfs acfa66bf-3738-4b70-86e8-7841a05b633c /home
/
zram0 [SWAP]
As root:
[root@brahe otheos]# bootctl install
Created "/boot/efi/EFI/systemd".
Created "/boot/efi/loader".
Created "/boot/efi/loader/entries".
Created "/boot/efi/EFI/Linux".
Copied "/usr/lib/systemd/boot/efi/systemd-bootx64.efi" to "/boot/efi/EFI/systemd/systemd-bootx64.efi".
Copied "/usr/lib/systemd/boot/efi/systemd-bootx64.efi" to "/boot/efi/EFI/BOOT/BOOTX64.EFI".
Random seed file /boot/efi/loader/random-seed successfully written (32 bytes).
Created EFI boot entry "Linux Boot Manager".
This has created the required folders in the ESP, placed the systemd-boot efi stubs in there, and created a boot entry in the bios. You can now boot using systemd-boot by selecting "Linux Boot Manager" in your Bios. Fedora will still boot to grub, as per usual
Your ESP now looks like this:
[root@brahe otheos]# cd /boot/efi/EFI/
[root@brahe EFI]# ls
BOOT fedora Linux systemd
The fedora folder is the original grub bootloader. systemd is what has been added.
Please find the project page here: https://github.com/isantop/kernelstub
otheos@brahe ~]$ mkdir git
[otheos@brahe ~]$ cd git
[otheos@brahe git]$ git clone https://github.com/isantop/kernelstub
Cloning into 'kernelstub'...
remote: Enumerating objects: 1307, done.
remote: Counting objects: 100% (6/6), done.
remote: Compressing objects: 100% (6/6), done.
remote: Total 1307 (delta 0), reused 5 (delta 0), pack-reused 1301
Receiving objects: 100% (1307/1307), 380.85 KiB | 2.82 MiB/s, done.
Resolving deltas: 100% (759/759), done.
[otheos@brahe kernelstub]$ sudo ./setup.py install > installed_files.txt
/usr/lib/python3.11/site-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.
warnings.warn(
/usr/lib/python3.11/site-packages/setuptools/command/easy_install.py:144: EasyInstallDeprecationWarning: easy_install command is deprecated. Use build and pip and other standards-based tools.
warnings.warn(
zip_safe flag not set; analyzing archive contents...
Check kernelstub has been installed:
[otheos@brahe ~]$ sudo kernelstub --help
usage: kernelstub [-h] [-p] [-e ESP,] [--esp-path ESP] [-r ROOT] [--root-path ROOT] [-k PATH,] [--kernel-path PATH] [-i PATH,]
[--initrd-path PATH] [-o "OPTIONS",] [--options "OPTIONS"] [-a "OPTIONS",] [--add-options "OPTIONS"] [-d OPTIONS]
[--delete-options "OPTIONS"] [-g LOG] [--log-file LOG] [-l | -n -s | -m] [-f] [-v]
Automatic Kernel EFIstub manager
Find (and add) your kernel options.
otheos@brahe ~]$ cat /etc/kernel/cmdline
root=UUID=acfa66bf-3738-4b70-86e8-7841a05b633c ro rootflags=subvol=root rhgb quiet
These are the minimum required options (default). You need those as default.
Find the kernel and initramfs:
[otheos@brahe ~]$ ls /boot
config-5.19.7-300.fc37.x86_64
efi
grub2
initramfs-0-rescue-e1228775572d405583e9bbee05d18a6b.img
initramfs-5.19.7-300.fc37.x86_64.img
loader
lost+found
symvers-5.19.7-300.fc37.x86_64.gz
System.map-5.19.7-300.fc37.x86_64
vmlinuz-0-rescue-e1228775572d405583e9bbee05d18a6b
vmlinuz-5.19.7-300.fc37.x86_64
There they are: vmlinuz-5.19.7-300.fc37.x86_64 and initramfs-5.19.7-300.fc37.x86_64.img
Prepare the command:
[otheos@brahe ~]$ sudo kernelstub -m -l -o "root=UUID=acfa66bf-3738-4b70-86e8-7841a05b633c ro rootflags=subvol=root rhgb quiet" -k /boot/vmlinuz-5.19.7-300.fc37.x86_64 -i /boot/initramfs-5.19.7-300.fc37.x86_64.img
This has now done the following:
[root@brahe otheos]# cd /boot/efi/EFI/
[root@brahe EFI]# ls
BOOT fedora Fedora_Linux-acfa66bf-3738-4b70-86e8-7841a05b633c Linux systemd
The new entry is Fedora_Linux-acfa66bf-3738-4b70-86e8-7841a05b633c. note the long string acfa66bf-3738-4b70-86e8-7841a05b633c is simply your root partition's UUID.
In this folder, kernelstub has copied the kernel, the initrd and the cmdline (options).
[root@brahe EFI]# cd Fedora_Linux-acfa66bf-3738-4b70-86e8-7841a05b633c/
[root@brahe Fedora_Linux-acfa66bf-3738-4b70-86e8-7841a05b633c]# ls
cmdline initrd.img vmlinuz.efi
This is found in /boot/efi/loader/entries
[root@brahe ~]# cd /boot/efi/loader/entries/
[root@brahe entries]# ls
'Fedora_Linux-brahe(acfa66bf)-current.conf'
The contents of this file are:#
[root@brahe entries]# cat Fedora_Linux-brahe\(acfa66bf\)-current.conf
title Fedora Linux (brahe)
linux /EFI/Fedora_Linux-acfa66bf-3738-4b70-86e8-7841a05b633c/vmlinuz.efi
initrd /EFI/Fedora_Linux-acfa66bf-3738-4b70-86e8-7841a05b633c/initrd.img
options root=UUID=acfa66bf-3738-4b70-86e8-7841a05b633c ro root=UUID=acfa66bf-3738-4b70-86e8-7841a05b633c ro rootflags=subvol=root rhgb quiet
This is found in /etc/kernelstub/configuration
It looks like this.
[root@brahe kernelstub]# cat configuration
{
"default": {
"kernel_options": [
"quiet",
"splash"
],
"esp_path": "/boot/efi",
"setup_loader": false,
"manage_mode": false,
"force_update": false,
"live_mode": false,
"config_rev": 3
},
"user": {
"kernel_options": [
"root=UUID=acfa66bf-3738-4b70-86e8-7841a05b633c",
"ro",
"rootflags=subvol=root",
"rhgb",
"quiet"
],
"esp_path": "/boot/efi",
"setup_loader": true,
"manage_mode": true,
"force_update": false,
"live_mode": false,
"config_rev": 3
}
You can see the options you passed with -o are now saved in the user options and are used every time, no need to issue them again.
More importantly the setup_loader is also set to true in the user options (and that's sufficient), so you don't need the -l switch anymore.
This tells kernelstub to update the loader file everytime (you want that).
Finally the manage_mode is also set to true which means that kernelstub will not create a bios boot entry (this works too, but we're using systemd-boot instead).
You are now ready for your first reboot. Remember to select Linux Boot Manager as the default option in your bios.
This is still Work in progress.
The benefit of using kernelstub is that when a new kernel is added, it moves the old one in to a second boot entry, named oldkern, and then copies the new one.
In order to do this, kernelstub looks to backup the older kernel, but it looks for it with a specific name, that is the original, with an extension .old.
In distributions with kernelstub (PopOS) a script runs after a kernel upgrade, which creates links and moves the old links to the .old place so that kernelstub can do its thing.
Here's a script that does that, please use with caution, and understand what it does before you use it! I'm not a programmer and I use csh, so if you want to use it you need to dnf install tcsh. But there are certainly better ways to do this.
#!/bin/csh
#Set ESP location
set loc = `ls /boot/efi/EFI/ | grep Fedora`
set esp = /boot/efi/EFI/$loc
#Move to /boot
cd /boot
#Find the latest kernel and initrd
set vm_new = `ls -1t --time=birth | grep vmlinuz-5 | head -1`
set in_new = `ls -1t --time=birth | grep initramfs-5 | head -1`
#Compare the latest kernel in /boot to the latest in the ESP
set comp = `cmp -b $vm_new $esp/vmlinuz.efi`
#Create a variable: it's the number of / in the paths in the output of comp
set tst = `echo $comp | grep -o '/' | wc -l`
#If there is a difference, tst is 6, otherwise is 0
#echo $tst
#if there is a difference, copy the new kernel, push the old to the previous position
if ($tst == "6") then
echo "New kernel found, copying files..."
# Move previous links to old
\mv vmlinuz vmlinuz.old
\mv initramfs initramfs.old
# Create new links
ln -s $vm_new vmlinuz
ln -s $in_new initramfs
# Update systemd-boot entries
kernelstub -k /boot/vmlinuz -i /boot/initramfs
else
echo "No new kernel found, exiting."
endif
Also check here for more: https://github.com/spxak1/weywot/blob/main/guides/fedora_systemd-boot.md