Please bring to Gentoo a bug in 2.20.13-14 drivers. I resolved that with upstream directly, and have just confirmed the patch fixes the problem for me on ~amd64. Upstread said "I have found the right root cause then it is just caused by memory corruption across regen. Not particularly easy to detect and warn about, you just hope to reproduce with valgrind and gdb." https://bugs.freedesktop.org/show_bug.cgi?id=56608 Reproducible: Always http://cgit.freedesktop.org/xorg/driver/xf86-video-intel/patch/?id=1e06d19a00f5a5a05369deeb3c5ae15b282c0f92
This has just became x11-drivers/xf86-video-intel-2.20.15 version bump.
2.20.15 in portage. Closing fixed. Thanks