Created attachment 34591 [details]
dmesg with drm.debug=0x07 option
This screen blank issue is experienced on 2.6.33 kernel and extended desktop mode, it wasn't reproduceable in Dual Twin/Clone mode. The only way to work around this is to disable compiz. I was running 1024x768 on both displays so the virtual desktop resolution shouldn't exceed the 2048 limit mentioned in http://bugs.freedesktop.org/show_bug.cgi?id=23718. In any case I am already running mesa 7.7 containing the fix mentioned in that thread.
I also don't see this issue when I'm running a 1024x768 with a 800x600 resolution display in extended mode with compiz enabled.
Created attachment 34592 [details]
Created attachment 34593 [details]
Created attachment 34762 [details]
Screenshot of extended desktop messed up
I've seen the similar behavior. Primary and Secondary display get messed up in extended desktop mode with Compiz enabled(see attached sreenshot). It works well with compiz disabled. It wasn't reproduceable in Dual Twin/Clone mode.
(In reply to comment #3)
> Created an attachment (id=34762) [details]
> Screenshot of extended desktop messed up
Xun, that looks like bug#27449.
I've tried the patch suggested in the previous comment and it did not help to resolve the screen blanking issue once virtual resolution reaches 2048x768.
compiz blanking on 2048 sounds like we have an off-by-one somewhere. The challenge will be to find the size of the textures and renderbuffers used by compiz for the desktop and check that they are all within the h/w constraints. Hmm, I wonder if Mesa actually enforces this, it would be best starting point to insert traps...
Author: Chris Wilson <firstname.lastname@example.org>
Date: Sat Jun 5 09:33:58 2010 +0100
i915: Fix off-by-one for drawing rectangle.
The drawing rectangle is given in *inclusive* pixel values, so the range
is only [0,2047]. Hence when rendering to a 2048 wide target, such as an
extended desktop, we would issue an illegal instruction zeroing the draw
Bug 27408: Primary and Secondary display blanks in extended
desktop mode with Compiz enabled
Hi Chris, thanks for the update. Can you provide a link to the patch so I can try it out?
Created attachment 36172 [details] [review]
Off-by-one drawrect fix.
Chris, your patch works on my side. Can you please cherry-pick it into mesa 7.8 branch? We do need this fix in 7.8.2 release.
Applied to 7.8 with Eric's blessing.
on Jul 24, 2016 at 18:26:45.
(provided by the Example extension).