ubuntu-x-swat team mailing list archive

[Bryce Harrington <803012@xxxxxxxxxxxxxxxxxx>]

** Description changed:

- Some UI elements from wine and fvwm don't render correctly when using
- the Intel driver. This can be observed in screenshots shown in the
- following links:
+ [Impact]
+ Widespread occurrences of rendering corruption with -intel.  It is cosmetic but looks very ugly.
+ 
+ The issue is caused by a  buggy optimization added in upstream commit
+ 3055d401, "uxa: Use Composite rather than solid blitter for PolyRect"
+ added in 2.12.0 (i.e. Maverick).
+ 
+ [Development Fix]
+ Upstream simply dropped the optimization entirely; their longer term plans are to provide better performance via the new SNA acceleration architecture (which we might ship in oneiric).
+ 
+ [Stable Fix]
+ See attached debdiff.  It is a backport of the upstream patch to natty.
+ 
+ [Test Case]
+ The bug exhibits itself in different ways for different people, and has different steps for reproducing.  For example, tabbing between windows, closing windows, selecting text, etc.  Generally you'll see corruption, blackness, or lines surrounding or related to text or dropdown windows.
+ 
+ But in general, booting on affected hardware and using for a period of
+ time will eventually trigger creation of the artifacts.
+ 
+ [Regression Potential]
+ Probably low.  In theory, removal of an optimization path would risk some performance loss, however in practice we're not seeing anyone reporting that the performance got noticeably worse.  In any case, it is not expected that the performance loss would be very large, and small performance impacts to resolve a screen corruption issue would probably be a fair trade.
+ 
+ [Original Report]
+ Some UI elements from wine and fvwm don't render correctly when using the Intel driver. This can be observed in screenshots shown in the following links:
  
  https://bugs.freedesktop.org/show_bug.cgi?id=28798
  https://bugs.freedesktop.org/show_bug.cgi?id=29401
  http://askubuntu.com/questions/29642/black-or-corrupt-ui-artifacts-under-wine/
  
  These issues have been attributed to errors in UXA utilising the 3D pipeline for core rendering.
  Upstream has disabled this to resolve this issue for now.
  
  I have applied their patch (commit: 855ced5a4eb67e287001ae22cb6489639c548cfa) to test this fix, which works for me here:
  https://launchpad.net/~smorar/+archive/bugfixes

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https://bugs.launchpad.net/bugs/803012

Title:
  Intel driver incorrectly renders some UI elements

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