Latest revision as of 19:59, 26 April 2022

Deprecate Legacy BIOS

Summary

Make UEFI a hardware requirement for new Fedora installations on platforms that support it (x86_64). Legacy BIOS support is not removed, but new non-UEFI installation is not supported on those platforms. This is a first step toward eventually removing legacy BIOS support entirely.

Owner

Name: Robbie Harwood, Jiří Konečný, Brian C. Lane
Email: rharwood@redhat.com

Current status

Targeted release: Fedora Linux 37
Last updated: 2022-04-26
devel thread
FESCo issue: #2780
Tracker bug: <will be assigned by the Wrangler>
Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

UEFI is defined by a versioned standard that can be tested and certified against. By contrast, every legacy BIOS is unique. Legacy BIOS is widely considered deprecated (Intel, AMD, Microsoft, Apple) and on its way out. As it ages, maintainability has decreased, and the status quo of maintaining both stacks in perpetuity is not viable for those currently doing that work.

UEFI originates with Intel, who evolved the spec themselves between 1998 and 2005 before opening it. Because the spec continues to evolve, saying when the "first" UEFI machine shipped is tricky - for instance, we care about many of the capabilities added in 2006, even though machines had already shipped by then, but Tiano (the reference open source implementation, used by at least libvirt/qemu, and originally an Intel project) actually predates that (2004). While perhaps not the first EFI machine, the first machine I can easily find that definitely used it is an Itanium from 2000.

It is inevitable that legacy BIOS will be removed in a future release. To ease this transition as best we can, there will be a period (of at least one Fedora release) where it will be possible to boot using the legacy BIOS codepaths, but new installations will not be possible. While it would be easier for us to cut support off today, our hope is that this compromise position will make for a smoother transition. Additional support with issues during the transition would be appreciated.

While this will eventually reduce workload for boot/installation components (grub2 reduces surface area, syslinux goes away entirely, anaconda reduces surface area), the reduction in support burden extends much further into the stack - for instance, VESA support can be removed from the distro.

Fedora already requires a 2GHz dual core CPU at minimum (and therefore mandates that machines must have been made after 2006). Like the already accepted Fedora 37 change to retire ARMv7 support, the hardware targeted tends to be rather underpowered by today’s standards, and the world has moved on from it. Intel stopped shipping the last vestiges of BIOS support in 2020 (as have other vendors, and Apple and Microsoft), so this is clearly the way things are heading - and therefore aligns with Fedora’s “First” objective.

Feedback

Dropping legacy BIOS was previously discussed (but not proposed) in 2020: https://lists.fedoraproject.org/archives/list/devel%40lists.fedoraproject.org/thread/QBANCA2UAJ5ZSMDVVARLIYAJE66TYTCD/

Important, relevant points from that thread (yes, I reread the entire thread) that have informed this change:

Some machines are BIOS-only. This change does not prevent their use yet, but they are effectively deprecated. grub2 (our default bootloader) is already capable of both BIOS and UEFI booting.
Drawing a clear year cutoff, let alone a detailed list of hardware this change affects, is basically impossible. This is unfortunate but unlikely to ever change.
There is no migration story from Legacy BIOS to UEFI - repartitioning effectively mandates a reinstall. As a result, we don’t drop support for existing Legacy BIOS systems yet, just new installations.
There is no way to deprecate hardware without causing some amount of friction.
While at the time AWS did not support UEFI booting, that is no longer the case and they support UEFI today.

During mailing list discussion of this change, concern was expressed that some of the smaller hosting providers who do not provision with UEFI today and do not also support Windows would drop Fedora rather than enabling UEFI. Given that the major virtualization solutions (vsphere, kvm, xen, bhve, virtualbox, ...) all support UEFI today, this would likely be exposing an existing capability rather than making a sweeping change. That said, it is always possible that providers may elect to drop Fedora rather than adjust their setups - be it for this change or any other change Fedora makes.

There are also a nonzero number of Fedora users running otherwise-capable machines that appear to be legacy-only. While this change does not prevent their use, opposition has been voiced toward preventing reinstalls and more generally deprecating them at all.

Benefit to Fedora

UEFI is required for many desirable features, including applying firmware updates (fwupd) and supporting SecureBoot. As a standalone change, it reduces support burden on everything involved in installing Fedora, since there becomes only one way to do it per platform. Finally, it simplifies our install/live media, since it too only has to boot one way per arch. Freedom Friends Features First - this is that last one.

Scope

Proposal owners:
- bootloaders: No change (existing Legacy BIOS installations still supported).
- anaconda: No change (there could be only optional cleanups in the code). However, it needs to be verified.
- Lorax: Code has already been written: https://github.com/weldr/lorax/pull/1205

Other developers:
- libvirt: UEFI works today, but is not the default. UEFI-only installation is needed for Windows 11, and per conversations, libvirt is prepared for this change.
- Virtualbox: UEFI Fedora installs are working and per virtualbox team, UEFI will be/is the default in 7.0+.
- The Hardware Overview page should be updated to mention the UEFI requirement: https://docs.fedoraproject.org/en-US/fedora/rawhide/release-notes/welcome/Hardware_Overview/

Release engineering: #Releng issue 10738

Policies and guidelines: N/A (not needed for this Change)

Trademark approval: N/A (not needed for this Change)

Alignment with Objectives: N/A

Upgrade/compatibility impact

Systems currently using Legacy BIOS for booting on x86_64 will continue to do so.

However, this modifies the baseline Fedora requirements and some hardware will no longer be supported for new installations.

How To Test

UEFI installation has been supported for quite a while already, so additional testing there should not be required.

User Experience

Installs will continue to work on UEFI, and will not work on Legacy BIOS. Our install media is already UEFI-capable.

Dependencies

None

Contingency Plan

Leave things as they are. Code continues to rot. Community assistance is required to continue the status quo. Current owners plan to orphan some packages regardless of whether the proposal is accepted.

Another fallback option could be, if a Legacy BIOS SIG organizes, to donate the relevant packages there and provide some initial mentoring. Longer term, packages that cannot be wholly donated could be split, though it is unclear whether the synchronization thereby required would reduce the work for anyone.

Contingency mechanism: Delay until next release.
Contingency deadline: Beta freeze
Blocks release? No

Documentation

See release notes.

Release Notes

Fedora 37 marks legacy BIOS installation as deprecated on x86_64 in favor of UEFI. While systems already using Legacy BIOS to boot are still supported, new legacy BIOS installations on these architectures are no longer possible. Legacy BIOS support will be removed entirely in a future Fedora.

(Additionally, the Hardware Overview page should be updated to mention the UEFI requirement.)

@@ Line 1: / Line 1: @@
-{{admon/important | Comments and Explanations | The page source contains comments providing guidance to fill out each section. They are invisible when viewing this page. To read it, choose the "view source" link.<br/> '''Copy the source to a ''new page'' before making changes!  DO NOT EDIT THIS TEMPLATE FOR YOUR CHANGE PROPOSAL.'''}}
-{{admon/tip | Guidance | For details on how to fill out this form, see the [https://docs.fedoraproject.org/en-US/program_management/changes_guide/ documentation].}}
 <!-- The actual name of your proposed change page should look something like: Changes/Your_Change_Proposal_Name.  This keeps all change proposals in the same namespace -->
-= Change Proposal Name <!-- The name of your change proposal --> =
+= Deprecate Legacy BIOS =
 == Summary ==
-<!-- A sentence or two summarizing what this change is and what it will do. This information is used for the overall changeset summary page for each release. Note that motivation for the change should be in the Benefit to Fedora section below, and this part should answer the question "What?" rather than "Why?". -->
+Make UEFI a hardware requirement for new Fedora installations on platforms that support it (x86_64).  Legacy BIOS support is not removed, but new non-UEFI installation is not supported on those platforms.  This is a first step toward eventually removing legacy BIOS support entirely.
 == Owner ==
-<!--
+* Name: [[User:rharwood| Robbie Harwood]], [[User:jkonecny| Jiří Konečný]], [[User:bcl| Brian C. Lane]]
-For change proposals to qualify as self-contained, owners of all affected packages need to be included here. Alternatively, a SIG can be listed as an owner if it owns all affected packages.
+* Email: rharwood@redhat.com
-This should link to your home wiki page so we know who you are.
--->
-* Name: [[User:FASAcountName| Your Name]]
-<!-- Include you email address that you can be reached should people want to contact you about helping with your change, status is requested, or technical issues need to be resolved. If the change proposal is owned by a SIG, please also add a primary contact person. -->
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 <!--- UNCOMMENT only for Changes with assigned Shepherd (by FESCo)
 * FESCo shepherd: [[User:FASAccountName| Shehperd name]] <email address>
 -->
 == Current status ==
@@ Line 31: / Line 21: @@
 <!-- Select proper category, default is Self Contained Change -->
-[[Category:SelfContainedChange]]
+[[Category:SystemWideChange]]
-<!-- [[Category:SystemWideChange]] -->
-* Targeted release: [[Releases/<number> | Fedora Linux <number> ]]
+* Targeted release: [[Releases/37 | Fedora Linux 37 ]]
 * Last updated: <!-- this is an automatic macro — you don't need to change this line -->  {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}}
 <!-- After the change proposal is accepted by FESCo, tracking bug is created in Bugzilla and linked to this page
@@ Line 42: / Line 31: @@
 ON_QA -> change is fully code complete
 -->
-* FESCo issue: <will be assigned by the Wrangler>
+* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/K5YKCQU3YVCTMSBHLP4AOQWIE3AHWCKC/ devel thread]
+* FESCo issue: [https://pagure.io/fesco/issue/2780 #2780]
 * Tracker bug: <will be assigned by the Wrangler>
 * Release notes tracker: <will be assigned by the Wrangler>
 == Detailed Description ==
-<!-- Expand on the summary, if appropriate.  A couple sentences suffices to explain the goal, but the more details you can provide the better. -->
+UEFI is defined by a versioned standard that can be tested and certified against.  By contrast, every legacy BIOS is unique. Legacy BIOS is widely considered deprecated (Intel, AMD, Microsoft, Apple) and on its way out.  As it ages, maintainability has decreased, and the status quo of maintaining both stacks in perpetuity is not viable for those currently doing that work.
+UEFI originates with Intel, who evolved the spec themselves between 1998 and 2005 before opening it.  Because the spec continues to evolve, saying when the "first" UEFI machine shipped is tricky - for instance, we care about many of the capabilities added in 2006, even though machines had already shipped by then, but Tiano (the reference open source implementation, used by at least libvirt/qemu, and originally an Intel project) actually predates that (2004).  While perhaps not the first EFI machine, the first machine I can easily find that definitely used it is an Itanium from 2000.
+It is inevitable that legacy BIOS will be removed in a future release.  To ease this transition as best we can, there will be a period (of at least one Fedora release) where it will be possible to boot using the legacy BIOS codepaths, but new installations will not be possible.  While it would be easier for us to cut support off today, our hope is that this compromise position will make for a smoother transition.  Additional support with issues during the transition would be appreciated.
+While this will eventually reduce workload for boot/installation components (grub2 reduces surface area, syslinux goes away entirely, anaconda reduces surface area), the reduction in support burden extends much further into the stack - for instance, VESA support can be removed from the distro.
+Fedora already requires a 2GHz dual core CPU at minimum (and therefore mandates that machines must have been made after 2006).  Like the already accepted Fedora 37 change to retire ARMv7 support, the hardware targeted tends to be rather underpowered by today’s standards, and the world has moved on from it.  Intel stopped shipping the last vestiges of BIOS support in 2020 (as have other vendors, and Apple and Microsoft), so this is clearly the way things are heading - and therefore aligns with Fedora’s “First” objective.
 == Feedback ==
-<!-- Summarize the feedback from the community and address why you chose not to accept proposed alternatives. This section is optional for all change proposals but is strongly suggested. Incorporating feedback here as it is raised gives FESCo a clearer view of your proposal and leaves a good record for the future. If you get no feedback, that is useful to note in this section as well. For innovative or possibly controversial ideas, consider collecting feedback before you file the change proposal. -->
+Dropping legacy BIOS was previously discussed (but not proposed) in 2020:
+https://lists.fedoraproject.org/archives/list/devel%40lists.fedoraproject.org/thread/QBANCA2UAJ5ZSMDVVARLIYAJE66TYTCD/
+Important, relevant points from that thread (yes, I reread the entire thread) that have informed this change:
+* Some machines are BIOS-only.  This change does not prevent their use yet, but they are effectively deprecated.  grub2 (our default bootloader) is already capable of both BIOS and UEFI booting.
+* Drawing a clear year cutoff, let alone a detailed list of hardware this change affects, is basically impossible.  This is unfortunate but unlikely to ever change.
+* There is no migration story from Legacy BIOS to UEFI - repartitioning effectively mandates a reinstall.  As a result, we don’t drop support for existing Legacy BIOS systems yet, just new installations.
+* There is no way to deprecate hardware without causing some amount of friction.
+* While at the time AWS did not support UEFI booting, that is no longer the case and they support UEFI today.
-== Benefit to Fedora ==
+During mailing list discussion of this change, concern was expressed that some of the smaller hosting providers who do not provision with UEFI today and do not also support Windows would drop Fedora rather than enabling UEFI.  Given that the major virtualization solutions (vsphere, kvm, xen, bhve, virtualbox, ...) all support UEFI today, this would likely be exposing an existing capability rather than making a sweeping change.  That said, it is always possible that providers may elect to drop Fedora rather than adjust their setups - be it for this change or any other change Fedora makes.
-<!-- What is the benefit to the distribution?  Will the software we generate be improved? How will the process of creating Fedora releases be improved?
-      Be sure to include the following areas if relevant:
-      If this is a major capability update, what has changed?
-           For example: This change introduces Python 5 that runs without the Global Interpreter Lock and is fully multithreaded.
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-           For example: This change allows package upgrades to be performed automatically and rolled-back at will.
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-      Does this improve specific Spins or Editions?
-           For example: This change modifies the default install of Fedora Workstation to be more in line with the base install of Fedora Server.
-      Does this make the distribution more efficient?
-           For example: This change replaces thousands of individual %post scriptlets in packages with one script that runs at the end.
-      Is this an improvement to maintainer processes?
-           For example: Gating Fedora packages on automatic QA tests will make rawhide more stable and allow changes to be implemented more smoothly.
-      Is this an improvement targeted as specific contributors?
-           For example: Ensuring that a minimal set of tools required for contribution to Fedora are installed by default eases the onboarding of new contributors.
-     When a Change has multiple benefits, it's better to list them all.
+There are also a nonzero number of Fedora users running otherwise-capable machines that appear to be legacy-only.  While this change does not prevent their use, opposition has been voiced toward preventing reinstalls and more generally deprecating them at all.
-     Consider these Change pages from previous editions as inspiration:
+== Benefit to Fedora ==
-     https://fedoraproject.org/wiki/Changes/Annobin (low-level and technical, invisible to users)
+UEFI is required for many desirable features, including applying firmware updates (fwupd) and supporting SecureBoot.  As a standalone change, it reduces support burden on everything involved in installing Fedora, since there becomes only one way to do it per platform.  Finally, it simplifies our install/live media, since it too only has to boot one way per arch.  Freedom Friends Features First - this is that last one.
-     https://fedoraproject.org/wiki/Changes/ParallelInstallableDebuginfo (low-level, but visible to advanced users)
-     https://fedoraproject.org/wiki/Changes/VirtualBox_Guest_Integration (primarily a UX change)
-     https://fedoraproject.org/wiki/Changes/NoMoreAlpha (an improvement to distro processes)
-     https://fedoraproject.org/wiki/Changes/perl5.26 (major upgrade to a popular software stack, visible to users of that stack)
--->
 == Scope ==
 * Proposal owners:
-<!-- What work do the feature owners have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
+** bootloaders: No change (existing Legacy BIOS installations still supported).
+** anaconda: No change (there could be only optional cleanups in the code). However, it needs to be verified.
+** Lorax: Code has already been written: https://github.com/weldr/lorax/pull/1205
-* Other developers: <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Other developers:
-<!-- What work do other developers have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
+** libvirt: UEFI works today, but is not the default.  UEFI-only installation is needed for Windows 11, and per conversations, libvirt is prepared for this change.
+** Virtualbox: UEFI Fedora installs are working and per virtualbox team, UEFI will be/is the default in 7.0+.
+** The Hardware Overview page should be updated to mention the UEFI requirement: https://docs.fedoraproject.org/en-US/fedora/rawhide/release-notes/welcome/Hardware_Overview/
-* Release engineering: [https://pagure.io/releng/issues #Releng issue number] <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Release engineering: [https://pagure.io/releng/issue/10738 #Releng issue 10738] <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 <!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)?  Is a mass rebuild required?  include a link to the releng issue.
 The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication -->
-* Policies and guidelines: N/A (not needed for this Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Policies and guidelines: N/A (not needed for this Change)
-<!-- Do the packaging guidelines or other documents need to be updated for this feature?  If so, does it need to happen before or after the implementation is done?  If a FPC ticket exists, add a link here. Please submit a pull request with the proposed changes before submitting your Change proposal. -->
 * Trademark approval: N/A (not needed for this Change)
-<!-- If your Change may require trademark approval (for example, if it is a new Spin), file a ticket ( https://pagure.io/Fedora-Council/tickets/issues ) requesting trademark approval from the Fedora Council. This approval will be done via the Council's consensus-based process. -->
-* Alignment with Objectives:
+* Alignment with Objectives: N/A
-<!-- Does your proposal align with the current Fedora Objectives: https://docs.fedoraproject.org/en-US/project/objectives/ ? It's okay if it doesn't, but it's something to consider -->
 == Upgrade/compatibility impact ==
-<!-- What happens to systems that have had a previous versions of Fedora installed and are updated to the version containing this change? Will anything require manual configuration or data migration? Will any existing functionality be no longer supported? -->
+Systems currently using Legacy BIOS for booting on x86_64 will continue to do so.
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+However, this modifies the baseline Fedora requirements and some hardware will no longer be supported for new installations.
 == How To Test ==
-<!-- This does not need to be a full-fledged document. Describe the dimensions of tests that this change implementation is expected to pass when it is done.  If it needs to be tested with different hardware or software configurations, indicate them.  The more specific you can be, the better the community testing can be.
+UEFI installation has been supported for quite a while already, so additional testing there should not be required.
-Remember that you are writing this how to for interested testers to use to check out your change implementation - documenting what you do for testing is OK, but it's much better to document what *I* can do to test your change.
-A good "how to test" should answer these four questions:
-. What special hardware / data / etc. is needed (if any)?
-. How do I prepare my system to test this change? What packages
-need to be installed, config files edited, etc.?
-. What specific actions do I perform to check that the change is
-working like it's supposed to?
-. What are the expected results of those actions?
--->
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == User Experience ==
-<!-- If this change proposal is noticeable by users, how will their experiences change as a result?
+Installs will continue to work on UEFI, and will not work on Legacy BIOS.  Our install media is already UEFI-capable.
- This section partially overlaps with the Benefit to Fedora section above. This section should be primarily about the User Experience, written in a way that does not assume deep technical knowledge. More detailed technical description should be left for the Benefit to Fedora section.
- Describe what Users will see or notice, for example:
-  - Packages are compressed more efficiently, making downloads and upgrades faster by 10%.
-  - Kerberos tickets can be renewed automatically. Users will now have to authenticate less and become more productive. Credential management improvements mean a user can start their work day with a single sign on and not have to pause for reauthentication during their entire day.
-  - Libreoffice is one of the most commonly installed applications on Fedora and it is now available by default to help users "hit the ground running".
- - Green has been scientifically proven to be the most relaxing color. The move to a default background color of green with green text will result in Fedora users being the most relaxed users of any operating system.
--->
 == Dependencies ==
-<!-- What other packages (RPMs) depend on this package?  Are there changes outside the developers' control on which completion of this change depends?  In other words, completion of another change owned by someone else and might cause you to not be able to finish on time or that you would need to coordinate?  Other upstream projects like the kernel (if this is not a kernel change)? -->
+None
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == Contingency Plan ==
+Leave things as they are.  Code continues to rot.  Community assistance is required to continue the status quo.  Current owners plan to orphan some packages regardless of whether the proposal is accepted.
-<!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration".  Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
+Another fallback option could be, if a Legacy BIOS SIG organizes, to donate the relevant packages there and provide some initial mentoring.  Longer term, packages that cannot be wholly donated could be split, though it is unclear whether the synchronization thereby required would reduce the work for anyone.
-* Contingency mechanism: (What to do?  Who will do it?) N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-<!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
-* Contingency deadline: N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-<!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
-* Blocks release? N/A (not a System Wide Change), Yes/No <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Contingency mechanism: Delay until next release.
+* Contingency deadline: Beta freeze
+* Blocks release? No
 == Documentation ==
-<!-- Is there upstream documentation on this change, or notes you have written yourself?  Link to that material here so other interested developers can get involved. -->
+See release notes.
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-N/A (not a System Wide Change)
 == Release Notes ==
-<!-- The Fedora Release Notes inform end-users about what is new in the release.  Examples of past release notes are here: http://docs.fedoraproject.org/release-notes/ -->
+Fedora 37 marks legacy BIOS installation as deprecated on x86_64 in favor of UEFI.  While systems already using Legacy BIOS to boot are still supported, new legacy BIOS installations on these architectures are no longer possible.  Legacy BIOS support will be removed entirely in a future Fedora.
-<!-- The release notes also help users know how to deal with platform changes such as ABIs/APIs, configuration or data file formats, or upgrade concerns.  If there are any such changes involved in this change, indicate them here.  A link to upstream documentation will often satisfy this need.  This information forms the basis of the release notes edited by the documentation team and shipped with the release.
-Release Notes are not required for initial draft of the Change Proposal but has to be completed by the Change Freeze.
+(Additionally, the Hardware Overview page should be updated to mention the UEFI requirement.)
--->

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