During review of dynamic page tables series, I was able to hit a lite restore bug with execlists. I assume that due to incorrect pd, the batch run out of legit address space and into the scratch page area. The ACTHD was increasing due to scratch being all zeroes (MI_NOOPs). And as gen8 address space is quite large, the hangcheck happily waited for a long long time, keeping the process effectively stuck. According to Chris Wilson any modern gpu will grind to halt if it encounters commands of all ones. This seemed to do the trick and hang was declared promptly when the gpu wandered into the scratch land. Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_gem_gtt.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index ccdb35f..26d1d45 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -2153,6 +2153,7 @@ static int alloc_scratch_page(struct i915_address_space *vm) return ret; } + fill_px(vm->dev, sp, ~0ULL); set_pages_uc(px_page(sp), 1); vm->scratch_page = sp; -- 1.9.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
