ammy log $ equery u xf86-video-intel     
[ Legend : U - final flag setting for installation]
[        : I - package is installed with flag     ]
[ Colors : set, unset                             ]
 * Found these USE flags for x11-drivers/xf86-video-intel-2.99.917_p20161007:
 U I
 - - debug : Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see
             https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces
 + + dri   : Enable direct rendering: used for accelerated 3D and some 2D, like DMA
 + + dri3  : (Restricted to <=x11-drivers/xf86-video-intel-2.99.917_p20160621)
             Enable DRI3 support
 + + sna   : Enable SandyBridge's New Acceleration (useful on all chipsets, not just SandyBridge)
 + + udev  : Enable virtual/udev integration (device discovery, power and storage device support, etc)
 + + uxa   : Enable UMA Acceleration Architecture
 - - xvmc  : Enables X-Video Motion Compensation support