Migrating to systemd-boot on Fedora
I have been using GRUB as the bootloader for my home server. Recently, I wanted to upgrade the boot drive (from 512GB to 1TB), and this necessitated regenerating the boot/ESP partitions as well as the bootloader.
Tip
See this for a detailed description of the entire boot process.
Unfortunately, reinstalling and configuring GRUB correctly was a major pain. I think part of the reason for that was that I wanted /boot to be on the same partition as my root filesystem (i.e., a single root partition scheme).
My setup then
The /boot directory contains the vmlinuz (compressed kernel) and initramfs (initrd, initial ramdisk) images.
After moving /boot to the OS partition (keeping /boot/efi on a separate partition), GRUB refused to boot, despite reinstalling it multiple times with dnf reinstall grub2-efi grub2-efi-modules shim-\*. It kept falling back to the GRUB shell and I had to run the commands listed here manually in order to boot.
In the end, I decided to move to systemd-boot. This is a UEFI boot manager which is functionally very simple. It uses the Boot Loader Specification - boot entries are configured by generic configuration files on the ESP, one per boot entry, which prevents the previous conflicts between different OSes. It can read kernel/initramfs images on a separate partition (via XBOOTLDR) as well.
My final setup was as follows:
#/etc/fstab
UUID=xxxxx-yyyyy-zzzzzz1 / btrfs noatime 0 0
UUID=5B3D-F60A /boot vfat umask=0077 0 2 # ESP
This setup is quite clean (to me) as all boot-related things are in one partition (and directory).
Note
Ideally, /boot would be on my BtrFS OS partition (via XBOOTLDR), and the ESP on /efi. This would let me checksum/snapshot the kernel/initrd images. However, XBOOTLDR uses the UEFI firmware to access filesystems, and BtrFS is not supported.
Setting it up
With reference from this guide.
Cleanup existing boot/EFI partitions
Unmount /boot and /boot/efi and delete the existing boot/EFI partitions (backing up if necessary).
Create a single vfat partition (via parted), and ensure the boot and esp flags are set (e.g. via set 1 esp on).
Remove GRUB and install systemd-boot
Install the bootloader with bootctl install.
Copy kernel and initrd images
First, check the output of kernel-install to determine what KERNEL_INSTALL_BOOT_ROOT is:
❯ kernel-install
Machine ID: 558115e7bb59469e95e37044fb809c91
Kernel Image Type: pe
Layout: bls
Boot Root: /boot
Entry Token Type: machine-id
Entry Token: 558115e7bb59469e95e37044fb809c91
Entry Directory: /boot/558115e7bb59469e95e37044fb809c91/6.14.9-200.fc41.x86_64
Kernel Version: 6.14.9-200.fc41.x86_64
Kernel: /usr/lib/modules/6.14.9-200.fc41.x86_64/vmlinuz
Initrds: (unset)
Initrd Generator: (unset)
UKI Generator: (unset)
Plugins: /usr/lib/kernel/install.d/40-dkms.install
/usr/lib/kernel/install.d/50-depmod.install
/usr/lib/kernel/install.d/50-dracut.install
/usr/lib/kernel/install.d/60-kdump.install
/usr/lib/kernel/install.d/90-loaderentry.install
/usr/lib/kernel/install.d/90-uki-copy.install
/usr/lib/kernel/install.d/92-crashkernel.install
/usr/lib/kernel/install.d/95-akmodsposttrans.install
Plugin Environment: LC_COLLATE=C.UTF-8
KERNEL_INSTALL_VERBOSE=0
KERNEL_INSTALL_IMAGE_TYPE=pe
KERNEL_INSTALL_MACHINE_ID=558115e7bb59469e95e37044fb809c91
KERNEL_INSTALL_ENTRY_TOKEN=558115e7bb59469e95e37044fb809c91
KERNEL_INSTALL_BOOT_ROOT=/boot
KERNEL_INSTALL_LAYOUT=bls
KERNEL_INSTALL_INITRD_GENERATOR=
KERNEL_INSTALL_UKI_GENERATOR=
KERNEL_INSTALL_STAGING_AREA=/tmp/kernel-install.staging.XXXXXX
Plugin Arguments: add|remove
6.14.9-200.fc41.x86_64
/boot/558115e7bb59469e95e37044fb809c91/6.14.9-200.fc41.x86_64
/usr/lib/modules/6.14.9-200.fc41.x86_64/vmlinuz
[INITRD...]
If it is not /boot, then you need to change it by editing /etc/kernel/install.conf and ensure BOOT_ROOT=/boot. Otherwise, the images will be installed to the wrong directory.
Recheck this again with kernel-install.
Then, you can install and copy over the kernel/initramfs images. Note that the install scripts also regenerate the initramfs for you, as well as run kernel-install. Kernel parameters are fetched from /etc/kernel/cmdline, and configuration for dracut (initramfs generator) is in /etc/dracut.conf.d.
Reboot
After this, confirm that your configuration is working with bootctl:
❯ sudo bootctl
System:
Firmware: UEFI 2.80 (American Megatrends 5.27)
Firmware Arch: x64
Secure Boot: disabled (setup)
TPM2 Support: yes
Measured UKI: no
Boot into FW: supported
Current Boot Loader:
Product: systemd-boot 256.15-1.fc41
Features: ✓ Boot counting
✓ Menu timeout control
✓ One-shot menu timeout control
✓ Default entry control
✓ One-shot entry control
✓ Support for XBOOTLDR partition
✓ Support for passing random seed to OS
✓ Load drop-in drivers
✓ Support Type #1 sort-key field
✓ Support @saved pseudo-entry
✓ Support Type #1 devicetree field
✓ Enroll SecureBoot keys
✓ Retain SHIM protocols
✓ Menu can be disabled
✓ Boot loader sets ESP information
ESP: /dev/disk/by-partuuid/a7ddf3f5-f9ce-41bf-80b2-36b2c8e15dfc
File: └─/EFI/systemd/systemd-bootx64.efi
Random Seed:
System Token: set
Exists: yes
Available Boot Loaders on ESP:
ESP: /boot (/dev/disk/by-partuuid/a7ddf3f5-f9ce-41bf-80b2-36b2c8e15dfc)
File: ├─/EFI/systemd/systemd-bootx64.efi (systemd-boot 256.15-1.fc41)
└─/EFI/BOOT/BOOTX64.EFI (systemd-boot 256.15-1.fc41)
Boot Loaders Listed in EFI Variables:
Title: Linux Boot Manager
ID: 0x0001
Status: active, boot-order
Partition: /dev/disk/by-partuuid/a7ddf3f5-f9ce-41bf-80b2-36b2c8e15dfc
File: └─/EFI/systemd/systemd-bootx64.efi
Title: UEFI OS
ID: 0x0002
Status: active, boot-order
Partition: /dev/disk/by-partuuid/a7ddf3f5-f9ce-41bf-80b2-36b2c8e15dfc
File: └─/EFI/BOOT/BOOTX64.EFI
Boot Loader Entries:
$BOOT: /boot (/dev/disk/by-partuuid/a7ddf3f5-f9ce-41bf-80b2-36b2c8e15dfc)
token: fedora
Default Boot Loader Entry:
type: Boot Loader Specification Type #1 (.conf)
title: Fedora Linux 41 (Server Edition)
id: 558115e7bb59469e95e37044fb809c91-6.14.9-200.fc41.x86_64.conf
source: /boot//loader/entries/558115e7bb59469e95e37044fb809c91-6.14.9-200.fc41.x86_64.conf
sort-key: fedora
version: 6.14.9-200.fc41.x86_64
machine-id: 558115e7bb59469e95e37044fb809c91
linux: /boot//558115e7bb59469e95e37044fb809c91/6.14.9-200.fc41.x86_64/linux
initrd: /boot//558115e7bb59469e95e37044fb809c91/6.14.9-200.fc41.x86_64/initrd
options: root=UUID=2a1d4d2a-7016-4f91-aa55-92d1b284668d ro rootflags=subvol=root noresume intel_iommu=on initcall_blacklist=sysfb_init >
If 'Default Boot Loader Entry' points to your OS, you're set, and you can reboot now.