Hi Dave,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   2a26d99b251b8625d27aed14e97fc10707a3a81f
commit: 85d1225ec066b2ef46fbd0ed1bae78ae1f3e6c91 drm/i915: Introduce & use new lightweight SGL iterators
date:   5 months ago
config: x86_64-randconfig-s2-10301238 (attached as .config)
compiler: gcc-4.4 (Debian 4.4.7-8) 4.4.7
reproduce:
        git checkout 85d1225ec066b2ef46fbd0ed1bae78ae1f3e6c91
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All errors (new ones prefixed by >>):

   cc1: warnings being treated as errors
   drivers/gpu/drm/i915/i915_gem_gtt.c: In function 'gen8_ggtt_insert_entries':
>> drivers/gpu/drm/i915/i915_gem_gtt.c:2367: error: 'gtt_entry' may be used uninitialized in this function
   drivers/gpu/drm/i915/i915_gem_gtt.c: In function 'gen6_ggtt_insert_entries':
   drivers/gpu/drm/i915/i915_gem_gtt.c:2442: error: 'gtt_entry' may be used uninitialized in this function

vim +/gtt_entry +2367 drivers/gpu/drm/i915/i915_gem_gtt.c

  2361					     enum i915_cache_level level, u32 unused)
  2362	{
  2363		struct drm_i915_private *dev_priv = to_i915(vm->dev);
  2364		struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
  2365		struct sgt_iter sgt_iter;
  2366		gen8_pte_t __iomem *gtt_entries;
> 2367		gen8_pte_t gtt_entry;
  2368		dma_addr_t addr;
  2369		int rpm_atomic_seq;
  2370		int i = 0;

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