On Sat, Apr 09, 2016 at 10:27:37AM +0100, Chris Wilson wrote: > For reasons unknown Sandybridge GT1 (at least) will eventually hang when > it encounters a ring wraparound at offset 0. The test case that > reproduces the bug reliably forces a large number of interrupted context > switches, thereby causing very frequent ring wraparounds, but there are > similar bug reports in the wild with the same symptoms, seqno writes > stop just before the wrap and the ringbuffer at address 0. It is also > timing crucial, but adding various delays hasn't helped pinpoint where > the window lies. This also seems to fix resume on my SNB-GT2, but I guess that is a different issue related to address 0. And long ago, I reported PNV also hung when resumed when it hang ringbuffers at address 0 - so I wonder if that's the same as well... -Chris -- Chris Wilson, Intel Open Source Technology Centre -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html