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      <base href="https://bugs.freedesktop.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [BDW] System hang while running Qt QML application, with unclaimed registers"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=97985">97985</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[BDW] System hang while running Qt QML application, with unclaimed registers
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>DRI
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>DRI git
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>x86-64 (AMD64)
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux (All)
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>DRM/Intel
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>anssi.hannula@bitwise.fi
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>i915 platform</th>
          <td>BDW
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=126897" name="attach_126897" title="BDW hang with intel-drm-nightly 20160927">attachment 126897</a> <a href="attachment.cgi?id=126897&action=edit" title="BDW hang with intel-drm-nightly 20160927">[details]</a></span>
BDW hang with intel-drm-nightly 20160927

The system hangs whenever a Qt QML application has run for a while (minutes or
hours). Qt QML uses OpenGL for rendering. It is a full system hang, not just
GPU.

E.g. simply running the "quickwidget" example application in Qt 5.6.1
(qtdeclarative/examples/quick/quickwidgets/quickwidget , with the rotating red
square) will trigger a full system freeze within a day (within minutes most of
the time).

When the application starts, within seconds (i.e. long before the freeze) there
is always an "Unclaimed register detected" warning in the log, one of these:
- Unclaimed register detected before writing to register 0x44324
- Unclaimed register detected before writing to register 0x220a8
- Unclaimed register detected before reading register 0x44408

This message is not there with e.g. glxgears (with which I have also not been
able to reproduce the hang so far).

With serial console I see no output at the time of freeze.

The issue happens also with latest intel processor microcode (loaded using the
early load mechanism).

With "intel_idle.max_cstate=1" kernel parameter the hang does not occur, or at
least it occurs so much more rarely that I haven't seen it.


The attached logs are all with drm-intel-nightly with drm.debug=0xe.

bdw-hang-nightly-20160927.txt contains a quickwidget hang captured via serial
port, and it also contains an unclaimed register warning for register 0x44324.

bdw-unclaimed-0x220a8.txt and bdw-unclaimed-0x44408.txt contain the other
variants of the "Unclaimed register" warning that I have seen, but I did not
wait for the freeze to actually happen in these instances (but I've seen the
hang happen with those messages in other runs with different kernel and without
drm debugging).



The setup is:

System architecture: x86_64

Kernel version: drm-intel-nightly 2016y-09m-27d-16h-32m-56s UTC (also seen in
4.4.18, 4.4.22, 4.8-rc8).

Linux distribution: Yocto 2.1-based build (mesa 11.1.1, X.org 1.18.0).

Machine model: Sintrones VBOX-3610

Display connector: DVI (appears as HDMI1)</pre>
        </div>
      </p>


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