OSX Yosemite Login Screen Artifacts Bug

When attempting to login to my late 2011 MacBook Pro today, I found my screen acting just like the screen in this video:

Jeez.

The problem

I spent some time googling random words attempting to describe the issue until I came across the above video on Youtube. The solution posted in the comments did not entirely work for me; I found that my flashing screen returned upon restart.

My friend Jimmy Hsu noticed that the solution involved

mv /System/Library/Extensions/ATI* .
mv /System/Library/Extensions/AMD* .

Which made him realize that issue was related to my graphics card. He remembered reading about issues with MacBook Pro’s from 2011, and a short trip to google landed me at this website which contained a very detailed solution.

In short, the hardware in late MacBook Pro 2011’s is faulty.

The solution

Apple has finally acknowledged the defect and are currently offering extended warranties and an entire repair program, according to Macworld.co.uk.

If one is looking for a short term solution to back up ones files (like I was), there is a solution that worked for me. My understanding is that this solution disables one’s graphics card drivers, which gets rid of the crazy flashing login screen. Then, one uses ‘switchGPU’, a program which is a wrapper for gfxCardStatus. switchGPU will enable integrated graphics when you login.

Short term solution

1. Boot into Single User Mode (cmd+S while booting)
2. Issue the commands (NOTE: some commands will take a short while to complete. Be patient)

   fsck -fy
   mount -uw /
   mkdir /Disabled_System_Library_Extensions
   cd /Disabled_System_Library_Extensions
   mv /System/Library/Extensions/ATI* .
   mv /System/Library/Extensions/AMD* .
   touch /System/Library/Extensions
   exit

One has now disabled their graphics card drivers.

1. Login to your account. Dont be suprised at how slow and ‘laggy’ your display is, we are about to fix that.
2. Install switchGPU by following the instructions in the README.md
3. Set your account to auto-login
4. Make sure ‘Automatic Graphics Switching’ setting is checked under the ‘Energy Saver’ section in System Preferences.

You should be able to use your system and backup your files!

The drawbacks

This solution is SHORT TERM. GET YOUR MACBOOK FIXED! The underlying issue is faulty hardware, and if you don’t get that fixed then your computer will experience complete failure at some point.

This solution requires auto-login, which has obvious security issues.

Taken from the answer on Earthwithsun.com:

The problem with this method is that the OS will switch to
discrete graphics whenever you run some app that uses graphics
acceleration. So this is not a permanent solution.