commit b1b38278e12b04cf9a227f6af2c24651cf6e8a85
Author: David Weinehall <david.weinehall@linux.intel.com>
Date:   Wed May 20 17:00:13 2015 +0300

    drm/i915: add a context parameter to {en, dis}able zero address mapping
    
    Export a new context parameter that can be set/queried through the
    context_{get,set}param ioctls.  This parameter is passed as a context
    flag and decides whether or not a GPU address mapping is allowed to
    be made at address zero.  The default is to allow such mappings.
    
    Signed-off-by: David Weinehall <david.weinehall@intel.com>
    Acked-by: "Zou, Nanhai" <nanhai.zou@intel.com>
    Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>