== Summary ==
This change replaces the legacy Linux frame buffer device (fbdev)
drivers that are still used in Fedora, with the latest simpledrm
driver and the DRM fbdev emulation layer.
== Owner ==
* Name: [[User:Javierm|Javier Martinez Canillas]]
* Email: javierm(a)redhat.com
* Name: [[User:Pbrobinson|Peter Robinson]]
* Email: pbrobinson(a)fedoraproject.org
== Detailed Description ==
The fbdev subsystem has been deprecated for over a decade and no new
platform should use it but instead write DRM drivers for their video
Yet, the Fedora kernel still enables support for some of the fbdev
drivers. Mainly for fbdev drivers that make use of the video frame
buffer that was initialized by the firmware. These are generic drivers
that could be used in different platforms since only grab an existing
frame buffer without trying to do any hardware initialization and
Examples of these drivers are simplefb (used in aarch64 machines with
Device Trees) and efifb (used in EFI machines) and vesafb (used in
machines with a VESA VGA graphics). But since the Linux v5.14, a new
simpledrm driver was introduced that is able to do the same that these
fbdev drivers. And just like any other DRM driver, it can rely on the
DRM subsystem fbdev emulation layer to provide a fbdev interface.
For this reason, there is no need for the fbdev drivers anymore and
instead the simpledrm driver could just be used.
== Benefit to Fedora ==
This change will allow to reduce the maintenance burden in the Linux
kernel since users won't use legacy fbdev drivers anymore but instead
a driver in the well maintained DRM subsystem. This will also move
Fedora one step close to being able to completely disable the fbdev
The latter is still not possible due the framebuffer console (fbcon)
needing to run on top of a frame buffer device. But at least this
change will remove the dependency with fbdev drivers and make fbcon
just use the DRM fbdev emulation layer in the meantime.
== Scope ==
* Proposal owners:
** Modify the following Linux kernel config options:
*** Disable fbdev drivers (e.g: `CONFIG_FB_EFI`, `CONFIG_FB_SIMPLE`) options.
*** Make `CONFIG_DRM` option built-in so the display can be enabled
without an initrd.
*** Enable the `CONFIG_SYSFB_SIMPLEFB` that registers a
simple-framebuffer platform device that is used to match the simpledrm
* Other developers:
** It should not affect other packages but may be that plymouth or
display managers could need some work.
** Test and watch for regressions.
* Release engineering: 
* Policies and guidelines: No changes needed.
* Trademark approval: No changes needed.
== Upgrade/compatibility impact ==
There should not be any impact on upgrade, this is a internal change
in the kernel and should be transparent for users.
== How To Test ==
* Install Fedora 36 and check that there is output in the video
console when removing the `rhgb quiet` parameters.
== User Experience ==
No visible changes are expected, as mentioned it is fully backward
compatible and transparent for users.
== Dependencies ==
== Contingency Plan ==
* Contingency mechanism: Revert the Linux kernel configuration changes.
* Contingency deadline: Beta Freeze
* Blocks release? No
* Blocks product? None
== Documentation ==
He / Him / His
Fedora Program Manager