F43 Change Proposal: Anaconda Drop Support UEFI on MBR (self-contained)

Wiki - https://fedoraproject.org/wiki/Changes/Anaconda_Drop_Support_UEFI_on_MBR
Discussion thread -
https://discussion.fedoraproject.org/t/f43-change-proposal-anaconda-drop-support-uefi-on-mbr-self-contained/157261

This is a proposed Change for Fedora Linux.
This document represents a proposed Change. As part of the Changes
process, proposals are publicly announced in order to receive
community feedback. This proposal will only be implemented if approved
by the Fedora Engineering Steering Committee.

== Summary ==
Enforce the use of GPT partition tables for all UEFI-based Fedora
installations for x86 architecture. This removes support for
installing Fedora in UEFI mode on MBR-partitioned disks on x86
systems. ARM and RISC-V remain unaffected.

== Owner ==
* Name: Anaconda team ([[User:kkoukiou|Katerina Koukiou]])
* Email: kkoukiou@redhat.com



== Detailed Description ==
Anaconda will no longer support installing in UEFI mode on
MBR-partitioned disks for X886. While the UEFI specification
technically permits booting from MBR (msdos) disks, in practice this
configuration is unreliable, inconsistently supported by firmware, and
not tested in Fedora.

Fedora's GRUB2 bootloader documentation already assumes the use of a
GPT partition table for UEFI installations.

By enforcing GPT in UEFI mode, Anaconda will provide a more robust
installation experience by avoiding bootloader crashes (e.g.,
efibootmgr failures).

Support for UEFI on MBR was originally added in
[https://github.com/storaged-project/blivet/pull/764 blivet#764] to
accommodate cloud image use cases, such as AWS, which at the time did
not support UEFI booting on GPT disks. These constraints no longer
apply to modern cloud platforms, making MBR-based UEFI setups
unnecessary for current Fedora deployments.

This change only applies to x86 systems booted in UEFI mode. Other
architectures (such as ARM and RISC-V) are not affected, as their UEFI
implementations may still depend on MBR partitioning.

== Feedback ==

== Benefit to Fedora ==
* Improved reliability: Eliminating support for MBR in UEFI
installations prevents bootloader failures caused by firmware or
efibootmgr being unable to register UEFI boot entries on MBR disks.

* Reduced support burden: Dropping an untested and rarely used
configuration makes Fedora easier to test and maintain. It also avoids
misleading users into thinking MBR+UEFI is a viable long-term setup.

== Scope ==
* Proposal owners: The
[https://github.com/rhinstaller/anaconda/pull/6484 upstream PR] is
ready

* Other developers:

* Release engineering: [https://pagure.io/releng/issues #Releng issue number]

* 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 ==
This change does not affect upgrades of existing Fedora systems, as it
only impacts the Anaconda installation path in UEFI mode on
MBR-partitioned disks. Systems that were previously installed with MBR
and UEFI may continue to function and upgrade normally, but new
installations via Anaconda will require GPT.

== Early Testing (Optional) ==
Do you require 'QA Blueprint' support? N

== How To Test ==
After [https://github.com/rhinstaller/anaconda/pull/6485 Anaconda PR
#6484] is merged, users can test this change by downloading a current
Fedora Rawhide ISO and attempting to install Fedora in UEFI mode on an
MBR-partitioned disk on a x86 system.

The installer should fail gracefully with a clear error message
indicating that GPT is required for UEFI installations.

== User Experience ==


== Dependencies ==


== Contingency Plan ==
* Contingency mechanism: N/A (not a System Wide Change)
* Contingency deadline: N/A (not a System Wide Change)
* Blocks release? N/A (not a System Wide Change)

== Documentation ==
N/A (not a System Wide Change)

== Release Notes ==


--
Aoife Moloney

Fedora Operations Architect

Fedora Project

Matrix: @amoloney:fedora.im

IRC: amoloney

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