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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [BDW] KHR-GL45.tessellation_shader.tessellation_shader_tessellation.gl_InvocationID_PatchVerticesIn_PrimitiveID occasionally fails"
href="https://bugs.freedesktop.org/show_bug.cgi?id=103837">103837</a>
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<th>Summary</th>
<td>[BDW] KHR-GL45.tessellation_shader.tessellation_shader_tessellation.gl_InvocationID_PatchVerticesIn_PrimitiveID occasionally fails
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<th>Product</th>
<td>Mesa
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>Drivers/DRI/i965
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<th>Assignee</th>
<td>intel-3d-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>nroberts@igalia.com
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<th>QA Contact</th>
<td>intel-3d-bugs@lists.freedesktop.org
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<pre>The CTS test
KHR-GL45.tessellation_shader.tessellation_shader_tessellation.gl_InvocationID_PatchVerticesIn_PrimitiveID
seems to occasionally fail at a rate of about 1.4%.
The test emits a bunch of tessellation patches with varying sizes, including
the maximum of 32 and does an instanced draw call. There are no vertex buffers
bound and all of the vertices have the same position. The tessellation shaders
write to 5 integer output varyings which are captured to a transform feedback
buffer. The test then scans the buffer to verify that it has the expected
values. When it fails, there are one or two vertices in this buffer that get
written with all zeroes instead of the expected values. These failed slots are
small and in the middle of the buffer so it doesn’t seem likely that this could
be a buffer configuration issue. I suspect it might be some hardware quirk but
I haven’t been able to find anything relevant in the workarounds in the
hardware docs.
The hardware where I can replicate it is a NUC with Intel(R) Iris Pro 6200
(Broadwell GT3e). However I am unable to replicate it on my laptop which has
Intel(R) HD Graphics 5500 (Broadwell GT2).</pre>
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