Comment 2 for bug 1783961

enabling CONFIG_KVM instead of enabling KVM via the dtb overlay will hard-disable all video acceleration of the upstream proprietary driver of the pi and make it completely unusable for any kind of setup that uses any upstram acceleration features from the raspberry pi foundation (i.e. via /opt/vc4 libs).

the proper way to enable KVM support on any pi is to set:

dtoverlay=vc4-kms-v3d

in the config.txt file of the bootloader, the kernel is specifically set up for this via the included raspberry pi foundation patches.

this might be pointless on arm64 which is not supported at all upstream by the raspberry pi foundation (beyond offering completely unsupported 64bit binaries for for developer tinkering) and thus does not offer any video acceleration via the proprietary driver anyway on this architecture.

but enabling CONFIG_KVM hardcoded in the kernel config for armhf will be fatal, please make sure this does not happen so users can still use vc4 accelerated video playback by manipulating the upstream-documented dtoverlay values on armhf builds.