Intel

intel is the open source graphics driver for Intel GMA onboard graphics cards, starting with the Intel 810.

Hardware detection
To choose the right driver, first detect the graphics card. The lspci tool can be used for this task:

This should show something like this:

Feature support
A full list of Intel CPU graphic capabilities can be found here.

Kernel
The following kernel options need to be activated:

The legacy fbdev support is required since kernel 3.14.14 at least for i915. For hybrid Intel/AMD system, follow also the steps of radeon (opensource) or fglrx (closed binary) drivers.

Since kernel version 4.4 the driver has been moved and the legacy fbdev support is now.

Driver
Portage uses the VIDEO_CARDS USE_EXPAND flag for enabling support for various graphics cards in packages. Setting VIDEO_CARDS in will pull in the correct video driver: (see the feature matrix)

"intel" is for and   resp. are for media-libs/mesa.

Check the USE flags of :

After making any changes update the system so the changes take effect by running the command with the   option:

VAAPI
Intel GMA X4500HD / G45 / GM45 and newer supports VAAPI hardware video acceleration.

xorg.conf
As xorg is not aware of i915 or i965 they will need to be addressed as Driver.

The X server is designed to work out-of-the-box, with no need to manually edit X.Org's configuration files. It should detect and configure devices such as displays, keyboards, and mice.

However, the main configuration file of the X server is the xorg.conf.

Troubleshooting

 * Guide, how to report bugs upstream
 * Guide, how to report bugs upstream
 * Guide, how to report bugs upstream
 * Guide, how to report bugs upstream

html5/vaapi gpu hangs
If your GPU hangs up when watching vaapi-accelerated video e.g. on youtube, you can try enabling your IOMMU:

Related upstream bug report.

KDM freezes
A workaround is to set  in all sections of the file, which starts with.

Black screen

 * According to this Debian wiki, CONFIG_FRAMEBUFFER_CONSOLE must be set to y (aka built-in to the kernel). Otherwise, it is possible to always have a black screen unless nomodeset is passed to the kernel, thus disabling kernel mode setting (KMS).  can be passed to the kernel command line to try to solve this kind of issue. This is usually done through the bootloader.
 * Kernel with version 4.2 or newer is needed with some gen8 chipsets.

Brightness doesn't change with keyboard shortcuts
First, make sure vendor compatibility is on in the kernel configuration. Toshiba for Toshiba, etc.

If it is, or when the brightness buttons are working, the issue is that the kernel can not detect where the brightness control is located.

Luckily, this is easy enough to modify, as long as the kernel version is 3.13.x and up.

Add to the kernel command line.

External resources

 * X.Org Wiki