Manually enabling the Intel driver for X11

create a file called /etc/X11/xorg.conf containing the following:

Section "Device"
Identifier "Configured Video Device"
Driver "intel"
EndSection

Section "Monitor"
Identifier "Configured Monitor"
EndSection

Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
EndSection


Ref: https://wiki.ubuntu.com/X/Bugs/Mavericki8xxStatus


framebuffer (fbdev) driver
==========================
This is a generic featureless driver like -vesa but works under KMS (-vesa does not work with KMS).


Kernel mode-setting (KMS)
=========================
shifts responsibility for selecting and setting up the graphics mode from X.org to the kernel. When X.org is started, it then detects and uses the mode without any further mode changes. This promises to make booting faster, more graphical, and less flickery.

Verifying KMS is loaded by
dmesg | grep drm

KMS is dependent on ACPI, so on some systems that actually support ACPI but for some reason Ubuntu disables ACPI, adding acpi=force to GRUB2 boot options may help KMS and the graphics card to load properly.


More at https://wiki.ubuntu.com/X/KernelModeSetting