Sample excerpt from Xorg logs:
gentoo-victoria log # cat Xorg.0.log | grep EE
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
// ...
[18.985] (EE) Failed to load module "fbdev" (module does not exist, 0)
Reason: there should be a fbdev driver in the following location but it is missing:
/usr/lib/xorg/modules/drivers/fbdev_drv.so
The official X.org documentation:
https://www.x.org/wiki/fbdev/
Driver for Linux framebuffer devices.
Solution: on Gentoo systems, install the package x11-drivers/xf86-video-fbdev.
