Forwarded from https://bugs.launchpad.net/ubuntu/+source/unity/+bug/726033
When rendering the Unity dash icons are frequently missing from the rendering.
This video is a good demonstration of the problem: https://launchpadlibrarian.net/68813544/unity-bug.ogv
This works on r600g, nouveau, i915 and i965, so it looks like it's a bug somewhere in r300g.
The dash rendering uses FBOs and ARB shaders, with glscissor for clipping.
Created attachment 45747 [details]
Created attachment 45748 [details]
Created attachment 45749 [details]
This occurs on both mesa master (as of 2011/04/18, shown in logs) and 7.10.2.
The bug can be reproduced on ATI R300/400/500 GPUs. These GPUs are no longer
supported by fglrx so I couldn't verify if it was strictly a driver issue or if
there was some error in our program code. However, the problem cannot be
reproduced with a Radeon HD 4670 and the open source driver (or fglrx). Nor can
it be reproduced with Intel GPUs such as the GMA 950 and above.
The bug manifest itself in the Unity Dash. When an action is performed to show
more icons in the dash, the rendering does not happen. Elements of the Dash
only appear after the mouse moves over them, but this is the result of Unity
refreshing the rendering. Some elements of the dash also disappear. This make
me think that clipping could be involved. Unity makes extensive use of opengl
there is now a workaround in this commit:
// jaytaoko: This is a hack for what looks like a bug (#726033) in the radeon opensource driver
// on R300/400/500. Rather than passing a null region to glScissor, we give the clip area a 1 pixel width.
Unity doesn't work here after upgrade from 10.10. It hangs after logging in.
Could you possibly make a simple OpenGL test case reproducing this bug? It shouldn't be hard.
Is it still an issue with current kernel and mesa ?
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You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/mesa/mesa/issues/334.