In 4.14 kernels, you could prevent the console from appearing on the framebuffer altogether by unsetting CONFIG_FRAMEBUFFER_CONSOLE (or forcing it to =n). I used this to make sure my framebuffer-based LCD display did not get overwritten by kernel messages or the cursor.
It seems that this hasn't worked since this commit:
As of commit in kernel:
6104c37094 fbcon: Make fbcon a built-time depency for fbdev framebuffer console is build in into framebuffer module and there's no standalone fbcon module. Therefore drop the kmod-fbcon and enable console in kmod-fb. The only targets which use these modules are imx6 and geode, both are on kernel 4.14 so no fallback for other kernels is introduced.
Being at that this commit also fixes autoload of fbdev for x86.
Am I right in thinking that that commit effectively hard-codes CONFIG_FRAMEBUFFER_CONSOLE=y in a way that can't be disabled through later config? If that's the case, is there a way to disable the framebuffer console other than patching that kernel module directly to disable the console functionality?