On Thu, Jun 25, 2015 at 06:35:14PM +0300, Mika Kuoppala wrote: > 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. > > v2: Use 0xffff00ff pattern (Chris) Thinking about this, could we add a scratch page checker to hangcheck? Just check the first/last u64 perhaps? Or random offset_in_page? -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
