Our team was able to run our developped application on the i.MX6Q SABRE EVK board with Linux system based on the Yocto (Morty) project (with kernel 4.9.11). Our application uses the background framebuffer ("/dev/fb0" device) together with the overlay framebuffer ("/dev/fb1" device) to get desired functionality for graphics.
Our next goal, we are working now, is to create a new Linux based SW platform running Linux kernel 4.14.0 (we use vanilla kernel sources with some our patches, the Yocto project is not involved any more). The new SW platform is running fine on the i.MX6Q SABRE EVK board, but there is only one framebuffer device spawned during the system startup - only the "/dev/fb0" framebuffer device is present, the "/dev/fb1" overlay framebuffer device is missing.
What system entity is responsible for spawning the overlay framebuffer device during the system statup ?
What shall we do to get the overlay framebuffer available ?
Thank you in advance.