DiRT Showdown and Bioshock Infinite both only render half of the screen - only the lower left of the two triangles. This happens right away, even at the splash screen.
The scalar VS backend appears to be at fault, because INTEL_DEBUG=vec4 fixes it.
Patch on list:
You probably meant https://patchwork.freedesktop.org/patch/86011/
Heh, whoops. Yes, that one :)
Author: Kenneth Graunke <email@example.com>
Date: Sat May 7 17:30:02 2016 -0700
i965: Clamp "Maximum VP Index" to 1 when gl_ViewportIndex isn't written.
Bug manifests with Mesa 11.2 (e.g. one in Ubuntu 16.04), but is gone with the latest Mesa from Git. -> Verified.
(Although title mentions BDW, verification of the issue and its fix were done on SKL.)