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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 - [i915] driver crashes with dual 4k monitors on Intel HD 520"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=99908">99908</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[i915] driver crashes with dual 4k monitors on Intel HD 520
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>unspecified
          </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>major
          </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>phil@phord.com
          </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></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=129834" name="attach_129834" title="xrandr --verbose">attachment 129834</a> <a href="attachment.cgi?id=129834&action=edit" title="xrandr --verbose">[details]</a></span>
xrandr --verbose

Bug description:

My laptop locks up hard (Alt-SysRq-B does not work) when I enable video modes
3840x2160 on both monitors and desktop is extended, not mirrored. If I use
3840x2160 on one monitor and 1920x1080 on the other, it seems stable.  When I
tried 2560x1440 on the 2nd monitor (the native resolution of my built-in laptop
display) it also locked up.

It locked up when I tried to use only one external monitor in 4k mode with my
laptop screen in native resolution (2560x1440), but I did not experiment with
that mode much, so I don't have as much specific information about it.

The crash is very reliable and immediate.

I tried some 4.10 kernel flavors, but I failed when trying to install drm-tip
for testing with latest code.


System environment:
-- chipset: Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz
-- system architecture: 64-bit
-- xf86-video-intel:
-- xserver: xorg-server 2:1.18.4-1ubuntu6
-- mesa: 
-- libdrm: 2.4.70-1
-- kernel: 4.8.0-37-generic
-- Linux distribution: Ubuntu 16.10
-- Machine or mobo model: Lenovo Carbon X1
-- Display connector: HDMI on OnePort dock

Reproducing steps:

Enable extended desktop on two monitors in 3840x2160 resolution. 

Additional info:

$ uname -m ; uname -r
x86_64
4.8.0-37-generic

Lenovo Thinkpad Carbon X1
    description: Notebook
    product: 20FB005LUS (LENOVO_MT_20FB_BU_Think_FM_ThinkPad X1 Carbon 4th)
    vendor: LENOVO
    version: ThinkPad X1 Carbon 4th
    width: 64 bits
    capabilities: smbios-2.8 dmi-2.8 smp vsyscall32
       description: Motherboard
       product: 20FB005LUS
       vendor: LENOVO
       physical id: 0
       version: SDK0J40697 WIN</pre>
        </div>
      </p>


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