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

        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - [SNA] Garbage in window after filling backbuffer with glDrawPixels on Mesa-10.1"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=77368">77368</a>
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>chris@chris-wilson.co.uk
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[SNA] Garbage in window after filling backbuffer with glDrawPixels on Mesa-10.1
          </td>
        </tr>

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

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

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>amonakov@gmail.com
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Driver/intel
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>xorg
          </td>
        </tr></table>
      <p>
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        <pre>Created <span class=""><a href="attachment.cgi?id=97258" name="attach_97258" title="reproducer">attachment 97258</a> <a href="attachment.cgi?id=97258&action=edit" title="reproducer">[details]</a></span>
reproducer

Starting from 10.1 release, Mesa/i915 has a blit fastpath for glDrawPixels.  It
seems to not work properly for some, but not all, users, instead producing a
black window or a window showing contents from elsewhere on the screen.  I've
been unable to reproduce it on my hardware.

Software versions on which the problem is observed: Xorg 1.15, xf86-video-intel
2.99.911, Mesa 10.1

So far it's known that UXA is not affected; with SNA: IVB and HSW are affected.

A few users affected by the problem are gathered at
<a href="https://github.com/amonakov/primus/issues/138">https://github.com/amonakov/primus/issues/138</a>; since I couldn't reproduce the
problem I'll encourage them to add themselves to CC here. 

A test case is attached.  It expects the number of frames to draw as the first
argument (./a.out 1000).</pre>
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