linux kernel - On-screen display driver -

i need write linux kernel module display message box on other windows on screen. , need drawing image in kernel, access picture user-space application not required. don't understand how this. framework should use - framebuffers or v4l? suppose direct programming of display controller not idea, because there other driver in kernel this. so, questions are: how interact between in-kernel drivers, , how specify picture should on top?

i grateful help.

what want can not done in way, since kernel not handle guis , not handle window systems. provides access video output devices in 1 form or another, actual drawing , compositing of screen done in user space.

now, kernel module have power overwrite frame buffer, but, noticed, there multiple interfaces different purposes. additionally, using 3d rendering 2d desktops quite common. hijacking 3d command stream purposes disproportionately difficult.

even if managed that, there no guarantee user space window system wouldn't overwrite message box immediately. maybe before reaches display.

so no, can't done in practical way directly kernel. best alternative user space daemon displaying message on kernel code's behalf through standard channels other gui program.