I don't know why the 8192 limit never has been raised. Maybe the hardware never adopted for higher resolutions. Anyway:
As soon as you try to configure your 11520x2160 desktop, you can find in the log:
[ 84.385] failed to add fb -22
-22 is invalid argument and that error comes from the kernel. You could boot your kernel with drm.debug=0x5e and may get more hints why it fails.
I don't know why the 8192 limit never has been raised. Maybe the hardware never adopted for higher resolutions. Anyway:
As soon as you try to configure your 11520x2160 desktop, you can find in the log:
[ 84.385] failed to add fb -22
-22 is invalid argument and that error comes from the kernel. You could boot your kernel with drm.debug=0x5e and may get more hints why it fails.