Fedora 44 is looking at replacing the Linux kernel’s console “FBCON” with the user-space-based KMSCON implementation. Eventually the hope remains to deprecate the FBCON/FBDEV code within the Linux kernel.
Jocelyn Falempe of Red Hat laid out the proposal for Fedora 44 to replace FBCON with KMSCON as the default VT console. Falempe elaborated on the benefits of KMSCON in the change proposal:
“fbcon is a terminal emulator in the kernel, which is not well maintained (it lost scrolling support a few years ago due to a CVE), and requires a fbdev emulation layer in the kernel, as all GPU drivers are using the newer drm interface. It still requires userspace executable like getty and bash to be useful.
kmscon is a simple terminal emulator based on linux kernel mode setting (KMS). It can replace fbcon for VT console, and provide better keyboard support, and better security.
This change will do the following: Install kmscon by default, and update the symbolic link /usr/lib/systemd/system/[email protected] to point to [email protected], to start kmscon by default when switching VT. kmscon should be the default also on non-graphical installation, as it doesn’t require any graphic library (only libdrm, to access the framebuffer).
This change won’t affect the installation, the boot process (like encryption password fallback), as fbcon will still be compiled in the kernel. User can still revert to fbcon if they want, or if kmscon has issue on their setup. If kmscon fails to launch, it will fallback to getty/fbcon.
Currently kmscon depends on opengl/mesa, because it has an optional opengl backend. But we don’t want that on non-graphical server installation. I will split the package in two, having something like kmscon and kmscon-gl for the optional gl renderer.”
KMSCON should provide a more configurable experience, better Unicode handling, better keyboard layout support, Pango font rendering to provide better experience, scrolling support, better security, and crash handling thanks to systemd. KMSCON is also working on screen rotation support and basic mouse/touchpad capabilities too.
Those wanting to learn more about this proposal to use KMSCON in place of FBCON by default as Fedora 44’s default VT console can find all the details via this change proposal.
