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m_star Author

Level 1

2 points

HD4000 graphics problems when using a very big external screen

Hello,

I just got a new LG 34UM95 (3440x1440) which can get connected via Thunderbolt or DVI. Screen detection and activation is working fine.

However the screen is corrupted when moving the mouse or activating the dock animation or scrolling a window, ...

Scenario:

- MacBook Pro Mid 2012 (Intel HD4000),

- MacOS X 10.9.3

- really big external display (3440x1440) connected via Thunderbolt or DVI

- both displays (integrated end external display) active at same time

Problem:

- graphic errors (framebuffer corruptions) on both screens ==> it looks like the framebuffer memory size or some DMA transfer addresses are miscalculated

- when scaling down the external resolution to something smaller (e.g. 2560x1080) everything is working fine

- when closing the MacBook and using the external display only the big screen works flawlessly

==> Could you please have a look at this and fix the framebuffer corruption?

==> This might also be a race condition where the HD4000 driver accesses RAM which it should not have access to and could lead to an security attack.

Thanks,

Maik

MacBook Pro, OS X Mavericks (10.9.3)

Posted on May 19, 2014 2:46 AM

39 replies

Mar 11, 2016 8:49 AM in response to aker11

To talk to any display except a genuine ThunderBolt display, Mini DisplayPort (a thunderBolt subset) is used. A cable that ends in a [full size] DisplayPort display end is very cheap, and provides best results.

At this writing the Mac does not yet support HDMI 2.0, but does support HDMI 1.4. Using a display with only an HDMI input may leave you with full resolution available only at 30Hz. Some Users find this so annoying they cannot live with it.

emamin

Level 1

4 points

Apr 12, 2016 1:58 AM in response to m_super_star

Dear m_super_star,

with El Captain 10.11.2 your instruction worked perfectly but If I would like to update El Captain to 10.11.4 I lose the previous setup for 34 inch display and your instruction doen't work anymore.

DO you have or some other guys of Apple support, some other instruction to see my 34 inch properly again?

Thanks

Apr 21, 2016 8:20 PM in response to emamin

Hi,

I am having a similar problem to emamin. I see that the fix was successful for many of you, but now on El Capitan 10.11.4 I dont seem to be able to use the Kext program to re-upload the modified Kext. It seems from what I have been reading that Apple has deprecated the commands that allow kext to be put in developer mode?

Any help is greatly appreciated!

Thanks,

Alex

May 19, 2016 10:13 PM in response to m_star

I am having this same issue and am on El Capitan 10.11.5 will the previous solutions work with kext file? @m_star

May 19, 2016 10:14 PM in response to emamin

Emamin,

Did you ever get this fixed? if so what did you do?

Thanks

pa290

Level 1

4 points

May 22, 2016 8:56 PM in response to subnetangel77

I'm running El Capitan 10.11.5 and using a Dell U3415W display on a mid-2012 MBA. I did all of the steps per m_super_star and gilmorej. Unfortunately, I'm still having the scramble issue on the lower part of the display after the screen comes out sleep when using the 3400 x 1440 resolution. Changing the resolution to 2560 x 1080 eliminates the scramble but I prefer to keep at the higher resolution, so at this point, I'm resorted to restarting the MBA whenever the scramble shows up. Let me know if anyone has any other solutions. Dell keeps stating they don't and won't support this display on Macs so hopefully Apple fixes this with the next El Capitan update.

Jun 26, 2016 2:59 PM in response to m_star

Thank you for posting these fixes. Unfortunately they did not work for me. I am on el Capitan, which might be the cause. Do you know if this should work regardels of your OSX version? Thank you.

matt_jcs

Level 1

4 points

Jun 27, 2016 6:07 AM in response to emamin

Hi Emamin,

Please let us know if you have tried another method 🙂

I'm on 10.11.5 El Capitan, and my MBA mid 2012 won't display anything on the LG 34UC98 at 3440x1440, I already use a thunderbolt cable, and tried all the instructions given by m_super_star

Waiting for the bug fix from Apple or anyone who has the solution.

Thanks

emamin

Level 1

4 points

Sep 29, 2016 9:58 AM in response to matt_jcs

Dear All,

I suppose that at the moment nobody knows how to fix this limit with El Captain. unfortunately I didn't find any other solution. if I use the huge display only (closing my 13" display) the max resolution works well, so I attached an External keyboard to work on 34 inch only.

I hope that some expert can help us.

thanks

HD4000 graphics problems when using a very big external screen