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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [llvmpipe] crashes when GL context is created and a previous context was shared"
href="https://bugs.freedesktop.org/show_bug.cgi?id=101556">101556</a>
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<th>Summary</th>
<td>[llvmpipe] crashes when GL context is created and a previous context was shared
</td>
</tr>
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<th>Product</th>
<td>Mesa
</td>
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<th>Version</th>
<td>17.1
</td>
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<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>Mesa core
</td>
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<th>Assignee</th>
<td>mesa-dev@lists.freedesktop.org
</td>
</tr>
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<th>Reporter</th>
<td>florianlink@gmail.com
</td>
</tr>
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<th>QA Contact</th>
<td>mesa-dev@lists.freedesktop.org
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=132131" name="attach_132131" title="Screenshot of the crash, fence pointer is NULL.">attachment 132131</a> <a href="attachment.cgi?id=132131&action=edit" title="Screenshot of the crash, fence pointer is NULL.">[details]</a></span>
Screenshot of the crash, fence pointer is NULL.
I built the current 17.1.3 release on Windows Visual Studio 2015 with LLVM 3.9
(and 4.0 as well).
When I start my Qt application, which creates some GL contexts, I get the crash
that you can see in the attached images, when one of the contexts is created.
I tracked the crash down to the following commit (4 month ago):
<a href="https://github.com/mesa3d/mesa/commit/043883647acaee0b2c67c1c6b496404ebb4e8d67">https://github.com/mesa3d/mesa/commit/043883647acaee0b2c67c1c6b496404ebb4e8d67</a>
As you can see in my screenshot, the fence pointer is NULL and it is not
checked before calling a function that needs a valid fence pointer.
It seems to happen when wglMakeCurrent(NULL,NULL) is called by Qt and the
context that was active before is a shared context, so the bad fence call
happens.</pre>
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