Open source driver by Oracle:

Relevant code is located in drm and i915 subfolders.

Martin Bochnig, creator of OpenSXCE, has backported the S12 driver to illumos:

Testing

 

SystemChipsetStatus
ThinkCentre M91pIntel HD Graphics 2000Working, tested from 1024x768 to 1920x1080, occasional glitches within the last 16pixels of the screen, crashes under heavy load.
ThinkPad X230Intel HD Graphics 4000Only basic testing, 1366x768.