I am testing a modified VDrift (no float fbos and no texture compression) on Fedora 18 x86-64 using mesa from git.
GL Renderer: Mesa DRI Mobile Intel® GM45 Express Chipset
Expected output (mesa git with r600): http://imageshack.us/a/img543/5606/r600.jpg
This is what I get (mesa git with i965): http://imageshack.us/a/img842/928/i965.jpg
This works for me on Ivybridge (using Mesa master from today).
The artifacts in the screenshot look kind of like the noise you'd get without the Gen4 SEND dependency workaround...or a 16-wide-texturing-on-8-wide-shaders bug. But if this was Mesa master, those should be working.
I'll have to check when I'm home and have access to a GM45. Unless someone else beats me to it, of course...
Sorry for not getting to this, still...
However, Chris just fixed a bug with a screenshot that looks extremely similar:
Screenshot of that bug:
The same code applies to original Gen4, so I bet it fixes this too.
Scratch the comment about original Gen4, I forgot you *are* on GM45. So it's almost certainly that same bug...
This patch does indeed fix the broken rendering in that trace.
I'll reference this bug number when committing the fix.
Fix is in master now.