[Piglit] Issue with Piglit pixel ownership assumptions

Alexander Goins agoins at nvidia.com
Mon Jul 20 14:44:13 PDT 2015

Hello all,

During some recent debugging, I seem to have discovered  an issue with Piglit that could cause problems with some drivers. With -auto, and without -fbo or PIGLIT_FORCE_WINDOW=1, Piglit defaults to rendering to the default framebuffer without mapping a window. This means that it doesn't take pixel ownership, which could cause a problem with some drivers, particularly NVIDIA's with Unified Back Buffer enabled. The OpenGL spec requires that pixel ownership be established in order to guarantee that the window system doesn't clobber the output. There are more details in the patch descriptions.

It would probably be best to deprecate the functionality of not showing a window altogether, making users use FBOs if they want offscreen rendering. I made a patch that simply removes that functionality. As a softer solution, however, I also made a patch that makes displaying the window the default, and replaced PIGLIT_FORCE_WINDOW with PIGLIT_NO_WINDOW, a flag that allows tests to run without mapping a window. This way, users that have been relying on the existing functionality can continue using it.

Both patches are included.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/piglit/attachments/20150720/5edb020d/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-winsys-framework-Always-show-window.patch
Type: application/octet-stream
Size: 2704 bytes
Desc: 0001-winsys-framework-Always-show-window.patch
URL: <http://lists.freedesktop.org/archives/piglit/attachments/20150720/5edb020d/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-winsys-framework-Default-to-showing-window.patch
Type: application/octet-stream
Size: 3092 bytes
Desc: 0001-winsys-framework-Default-to-showing-window.patch
URL: <http://lists.freedesktop.org/archives/piglit/attachments/20150720/5edb020d/attachment-0001.obj>

More information about the Piglit mailing list