The ATI R300 is a very “special” and rather old GPU. It supports OpenGL 2 with one well-known limitation: there is no full non-power-of-two-texture support. KWin has code to handle this situation, nevertheless I broke our R300 support completely one week ago just before the branching of 4.7 without noticing it.
R300 used to be a very important Notebook GPU chip, so we cannot just stop to support it. I am sure that I will fix the regression with the help of users willing to test my patches, but for the long run it’s no solution. Even if we fix this regression I am (after reading our code again) very sure that some new features are not working at all with R300.
Given the situation that we do not notice such regressions during development, it is likely that changes will break support in future again (at least I am not able to develop correctly without testing ;-). This makes it very difficult as we cannot easily bisect. I see only one real solution: I need to have such a GPU to be able to test recent changes for regressions and implement the (rather trivial) adjustments for R300.
If anyone has such an old card and would be willing to donate it for KWin development, please get in contact with me.
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