Build Fedora Cloud Images with Hybrid BIOS+UEFI Boot Support
With recent changes in public cloud widely accepting the use of UEFI boot, it would be consistent to add hybrid boot in support of both unifying the legacy (BIOS) and UEFI boot to the Fedora Linux cloud base images.
- Name: David Duncan, Chris Murphy, Michel Alexandre Salim, Davide Cavalca, Neal Gompa, Dusty Mabe
- Email: email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org
- Products: Fedora Cloud Edition
- Responsible WGs: Fedora Cloud WG
- Targeted release: Fedora Linux 35
- Last Updated: 2021-06-21
- FESCo Issue: #2621
- Tracker bug: #1972377
- Release notes tracker: #703
The Fedora Cloud Edition image will be updated to be configured with multiple partitions and a GPT label, instead of a single partition and implicit MBR.
The partition order will be:
- BIOS boot
- EFI System (FAT32)
- /boot (ext4)
- / (btrfs)
Benefit to Fedora
This is a continuation from the changes outlined in the Fedora Linux 34 changes to unify the Grub configuration files. There has been an overwhelming support in the public cloud architectures leading to widespread support for UEFI boot in support of migration work. This also adds support for other anticipated changes that would require this modification to include the boot partitions; both legacy boot as a fallback through the BIOS boot partition and UEFI boot through the EFI system partition. This is going to require a group of modifications to the cloud base, including modifying the partition to support UEFI and a disk label change to GPT. With this change in place, the images will have greater flexibility to support file systems, such as btrfs, for boot across a number of supported providers and environments.
- To have a consistent configuration across all the architectures
- Allows the same image to be booted using either UEFI or legacy BIOS.
- Allow easier migration from one environment to another where there is potentially a change in boot loader.
- Use the same documentation and commands for the available cloud architectures instead of having special cases for different environments.
- Align with images generated by COSA, KIWI, and OSBuild on how the GRUB configuration files are used.
- Align with other installation methods on how the partitions under
- Align with other distributions, like CentOS and openSUSE, on support for GRUB configuration
- Proposal owners:
- Submit PRs for Cloud Edition kickstarts to produce hybrid boot.
- Release engineering: #10143
- Policies and guidelines: N/A
- Trademark approval: N/A
Change will not affect upgrades.
How To Test
Once the change lands in Rawhide, spin up the images in AWS, GCP, and KVM/OpenStack to test to see systems boot and run. Where possible, test images on cloud virtual machines types where both boot methods are supported.
Verify that the general data partition is properly grown in the case that the root volume is larger than the image default.
- Mostly transparent.
- Consistent recovery experience with other distributions and builds of Fedora Linux.
No extra documentation is required reading for users. Supporting recovery documentation is already available.
Fedora Linux cloud images are updated to boot both UEFI and legacy boot (BIOS) through a hybrid configuration.