Switch Fedora Cloud to /boot as a Btrfs subvolume
Summary
Eliminate the separate /boot partition on Fedora Cloud images
Owner
- Name: Neal Gompa, David Duncan
- Email: ngompa13@gmail.com, davdunc@amazon.com
Current status
- Targeted release: Fedora Linux 44
- Last updated: 2025-11-19
- Announced
- Discussion thread
- FESCo issue: #3506
- Tracker bug: <will be assigned by the Wrangler>
- Release notes tracker: <will be assigned by the Wrangler>
Detailed Description
The images produced by Fedora Cloud for Cloud platforms and Vagrant will drop the separate /boot in favor of a Btrfs subvolume. This will not apply to UEFI-UKI and s390x Cloud images due to limitations of those platforms.
Feedback
Benefit to Fedora
Fedora Cloud Edition is typically deployed as images of fixed sizes and grown on deployment, so it is attractive for us to minimize the footprint of the image up-front. Since Fedora Cloud images do not rely on grubenv features like the GRUB Hidden Menu feature (which requires resolving rhbz#2372973 first), we can easily consolidate the bootloader data on the Btrfs volume. By using a Btrfs subvolume, it can be trivially omitted from any snapshot mechanisms used on the deployment while avoiding space contention for boot data and the rest of the operating environment data.
Scope
- Proposal owners: Merge fedora-kiwi-descriptions#228
- Other developers: N/A
- Release engineering: #13005
- Policies and guidelines: N/A (not needed for this Change)
- Trademark approval: N/A (not needed for this Change)
- Alignment with the Fedora Strategy: N/A (not needed for this Change)
Upgrade/compatibility impact
There are no compatibility impacts, as this only affects new Cloud deployments with Fedora 44 or higher.
How To Test
Once the kiwi-descriptions PR is merged, images should be available in the new configuration. Just boot them in the platform of your choice to test.
User Experience
This should be transparent to users.
Contingency Plan
- Contingency mechanism: Revert the pull request to go back to separate
/bootvolume. - Contingency deadline: Final Freeze
- Blocks release? Yes
Documentation
N/A (not a System Wide Change)
Release Notes
Fedora Cloud images (except the UEFI-UKI images) on all architectures except IBM Z systems no longer have a separate /boot partition, and instead now ship /boot as a subvolume in the main Btrfs operating system volume. This allows for much better space utilization and smaller images.
