[Piglit] Issue with Piglit pixel ownership assumptions

Ilia Mirkin imirkin at alum.mit.edu
Wed Aug 12 20:56:19 PDT 2015

Unfortunately the patches were attached, which greatly increases the effort
required to review. Could you send this out inline using git send-email or
equivalent mechanism?
On Aug 12, 2015 8:54 PM, "James Jones" <jajones at nvidia.com> wrote:

> The PIGLIT_NO_WINDOW patch seems like the way to go to me, since
> defaulting to unreliable behavior seems bad, but allowing users to fall
> back to it to test on drivers that don't enforce pixel ownership seems
> fine.  I'd prefer if someone outside NVIDIA could review as well, but for:
> 0001-winsys-framework-Default-to-showing-window.patch
> Reviewed-by: James Jones <jajones at nvidia.com>
> I'll commit this soon if no one objects.
> Thanks,
> -James
> On 07/20/2015 02:44 PM, Alexander Goins wrote:
>> 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.
>> Thanks,
>> Alex
>> _______________________________________________
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> Piglit at lists.freedesktop.org
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