Insert extra logging (very verbose) for common GEM errors

configname: CONFIG_DRM_I915_ERRLOG_GEM

Linux Kernel Configuration
└─>Device Drivers
└─>Graphics support
└─>drm/i915 Debugging
└─>Insert extra logging (very verbose) for common GEM errors
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Enable additional logging that may help track down the cause of
principally userspace errors.

Recommended for driver developers only.

If in doubt, say "N".