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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Xorg segfault on cpu which does not support PAT"
href="https://bugs.freedesktop.org/show_bug.cgi?id=110774">110774</a>
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<th>Summary</th>
<td>Xorg segfault on cpu which does not support PAT
</td>
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<th>Product</th>
<td>Mesa
</td>
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<th>Version</th>
<td>git
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>All
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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
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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>ssheribe@redhat.com
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<th>QA Contact</th>
<td>intel-3d-bugs@lists.freedesktop.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=144351" name="attach_144351" title="gdb bt">attachment 144351</a> <a href="attachment.cgi?id=144351&action=edit" title="gdb bt">[details]</a></span>
gdb bt
My setup is as follow:
OS: fedora 30 5.0.11-300
cpu: QEMU Virtual CPU 2.5+ (without PAT - qemu's default)
gpu: assigned vGPU using GVTg
mesa-dri-drivers: 19.0.3-1
xorg-x11-server-Xorg: 1.20.4-3
(This is a vm running on top of fedora 30 host, same kernel with Intel
i7-6600u)
When i'm running inside xorg session and trying to open firefox, xorg crashes.
bisecting points to this patch:
54c823ec790427acbea31212a6ed30a17bd25ff0 (mesa)
It seems that in case cpu does not support PAT, mapping may fail (brw_bo_map_wc
fails without PAT and won't fallback since MAP_RAW is set) so that
intel_miptree_map_raw will use *dst when it's NULL, passing it to
linear_to_tiled which is trying to access *dst(=NULL).
Backtrace is attached.</pre>
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