I'm experiencing constant computer freezes running programs with 3D
accelerated output, both under Debian Jessie (Debian 8.0) and with Debian
Sid. Suddenly screen freezes and only the mouse moves. Sometimes the
computer seems to keep running (for example, if there was playing music it
is still playing). Sometimes complete freezes. Once fronzen, sometimes I
can switch (blindy!) to a text console, log in as root and issue a
shutdown, but usually I can't.

The problem is quite random but it happens mostly (but not only) while
using Google Chrome. Google Earth, and KDE with Open-GL and desktop effects
also trigger the bug frequently. Almost any Open-GL program can trigger it.
I noticed it can be "forced" to appear using Chrome and webgl. For example,
if I visit http://sci.esa.int/where_is_rosetta/ or
http://stars.chromeexperiments.com/ and start to rotating and zooming
in/out the system freezes in less than 10 minutes.

I tested some workarounds. As recomended here:
https://blog.sleeplessbeastie.eu/2014/11/30/i915-and-hangcheck-timer-elapsed-error/

- Disable VT-x in BIOS
- Add i915.semaphores=1 to kernel boot

But no success.

From Archwiki (
https://wiki.archlinux.org/index.php/Intel_graphics#X_freeze.2Fcrash_with_intel_driver)
I tried also:

- Option "AccelMethod" "uxa"
- Option "AccelMethod" "sna"

And still freezing. I even tried:

- Option "TearFree" "true"

because version 2.99.917-1 has terrible tearing in my system (version
2:2.21.15-2+b2 in Jessie works like a charm: zero tearing), but still
freezing.

Debian Jessie is much less verbose so I'll post the logs I get in Debian
Sid: