Missing "/dev/fb1" overlay framebuffer device in Linux on the i.MX6Q

[miroslavmusil]

Hello,

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.

Best regards

Miroslav Musil

[Bio_TICFSL]

Hi Miroslav,

If you are not able to see the fb1, fb2, fb3, etc it will be imposible to overlay data, you should check why are you not able to see the framebuffer

[frantisekhacker]

Hi Alfred,

I work together with Miroslav.

The issue is that in kernel 4.9.11 we can see fb0, fb1, fb2 on sabresd devel board

and in kernel 4.14.0 we can see fb0 only - on the same HW sabresd devel board!

Do you know where to start to dig into?

Thank you,

FH