Bug 22538

I committed a fix last week to mesa_7_5_branch that fixes and additional front-buffer rendering issue.  It might fix this problem as well.

commit 2d86503471cb8691ce266342810237fc1b15a7b2
Author: Ian Romanick <ian.d.romanick@intel.com>
Date:   Fri Jun 26 13:30:16 2009 -0700

    intel / DRI2: Additional flush of fake front-buffer to real front-buffer
    
    To maintain correctness, the server will copy the real front-buffer to
    a newly allocated fake front-buffer in DRI2GetBuffersWithFormat.
    However, if the DRI2GetBuffersWithFormat is triggered by glViewport,
    this will copy stale data into the new buffer.  Fix this by flushing
    the current fake front-buffer to the real front-buffer in
    intel_viewport.
    
    Fixes bug #22288.

*** This bug has been marked as a duplicate of bug 21774 ***

I'll pay more attention next time.

(In reply to comment #1)
> I committed a fix last week to mesa_7_5_branch that fixes and additional
> front-buffer rendering issue.  It might fix this problem as well.
> 
> commit 2d86503471cb8691ce266342810237fc1b15a7b2
> Author: Ian Romanick <ian.d.romanick@intel.com>
> Date:   Fri Jun 26 13:30:16 2009 -0700
> 
>     intel / DRI2: Additional flush of fake front-buffer to real front-buffer
> 
>     To maintain correctness, the server will copy the real front-buffer to
>     a newly allocated fake front-buffer in DRI2GetBuffersWithFormat.
>     However, if the DRI2GetBuffersWithFormat is triggered by glViewport,
>     this will copy stale data into the new buffer.  Fix this by flushing
>     the current fake front-buffer to the real front-buffer in
>     intel_viewport.
> 
>     Fixes bug #22288.
> 


It didn't fix it here, but I am not the original reporter and am on mesa 7.6 up to the "i915: Fix assertion failure on remapping a non-BO-backed VBO." commit (57a06d3a48c9af1067ec05e3ad96c58f4b9b99be on 06-30 which includes your above mentioned commit). Dropdown menus still dont render unless I use a static mesa blender version or LIBGL_ALWAYS_SOFTWARE=1. This is on a 945GME with -intel xserver and mesa all built from master today and the problem has existed since at least april. This is a backtrace from crashes that used to happen when clicking on a dropdown with texture tiling turned on if it helps any. That issue is fixed now but I dont know if it would help narrow down where the problem might be happening.

http://sarvatt.com/downloads/blender_bt.txt

*** Bug 22998 has been marked as a duplicate of this bug. ***

*** Bug 22994 has been marked as a duplicate of this bug. ***

https://bugs.freedesktop.org/show_bug.cgi?id=21774 which is supposed to be a duplicate of this bug, seems to address a different bug than https://bugs.freedesktop.org/show_bug.cgi?id=22998 which is also supposed to be a bug of this one.
The first one with ID 21774 says that menus are black or white, but #22998 says that they are not drawn at all (no refresh/change of the screen). And some user having the black/white issue in #21774 says it's also present in xf86-video-intel/2.7.99.901, but #22998 explicitly states that the problem was introduces by xf86-video-intel/2.7.99.902.
So I'd rather assume that #21774 and #22998 are different issues so they cannot be both duplicates of this bug? Although the user comments seem often to mix up both issues.

commit fd65418f600874b05f902b622078b40bc1abb24a
Author: Eric Anholt <eric@anholt.net>
Date:   Mon Aug 3 14:27:41 2009 -0700

    intel: Fix inverted test for disabling flushing of front buffer output.
    
    The comment disagreed with the code, and nicely drew my eyes to what was
    going wrong.
    
    Bug #21774 (blender)
    Bug #21788 (readpix)

Mass version move, cvs -> git