UPDATE Apr 27: Not unexpectedly, some of my assumptions were wrong. After rebooting at some point post 10.14.4 update, I hung at the gray boot screen (just after executing gIOScreenLockState 3). Reapplied NVRAM to no use. So I assume one of the drivers in parrotgeeks update route was choking 10.14.4. Then, I stumbled on dosdudes acceleration fix for 10.14.4 where folks were hanging at same spot. Most important finding I have is that when I was having issues with AMD drivers being deleted from /System/Library/Extensions, I assumed is was related to the Mojave legacy video patcher in addition to the GPUDisabler as well. Wrong. The problem was solely the GPUDisabler. After doing a repair install, with GPUDisabler fully removed (described below) I apply latest Mojave legacy video patcher as recommended for an 8,x MBP. Sweetness - boots fine and have full use of my dimming and sleep with chilly dGPU VCORE = 0. Updated below to reflect latest finding.
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Hoping this is something folks can make use of. Thanks to all the folks that are keeping our aging machines alive. If the below back story sounds like something you have experienced, maybe this post will be of use to you. Of course, everyones situation can be different and this may not work for you and may even make matters worse
. Take this with a grain of salt:
- 2nd logic board with a failed GPU on my Macbook Pro 17" 8,3. Tired of fixing / replacing, so sought software solutions a few months back.
- Installed gfxCardStatus v2.1. This worked for the most part. But sometimes boots would hang, presumably when the nvram settings got lost.
- Stumbled on dosdudes GPUDisabler. Seemed to work consistently, but at the cost of losing sleep and dimming functions due to the nature of the solution. It removes the the AMD drivers from /System/Library/Extensions, backing them up to /.AMD_Backup.
- Then I decided to upgrade to Mojave using dosdudes patcher with default options for a MBP 8,3, which includes legacyVideo as an option.
- Missing sleep and dimming functions, I starting exploring alternative methods to getting past a bum GPU without losing key functions. At one point in my trials, I thought I found the solution but lacking knowledge about what exactly GPUDisabler and Mojave Patcher legacyVideo patch does, I had difficult recreating the success and hit many failed states forcing recovery.
1. Install gfxCardStatus v2.1 - This seems to be reliable in most cases. It did fail in certain boot up scenarios, presumably where the nvram setting was reset due to a pram reset or OS update. I don't think gfxCardStatus sets the nvram. Once installed, go to settings and ensure set to load at startup, disable checking for updates (since many have stated that post v2.1 does not work as expected), and select power based switching in advanced ; setting both to Integrated
2. NVRAM Disable Script - In my drive root, I created a script to re-issue the dGPU nvram setting. This way, I can always go to single-user mode and execute it to get my system to boot. Someone else had a good write-up on this here (go down to Preventative Measures for Future Use) : (doesn't like links maybe - search for post 875 in article "force-2011-macbook-pro-8-2-with-failed-amd-gpu-to-always-use-intel-integrated-gpu-efi-variable-fix".
3. Remove dosdudes GPU Disabler (if you installed it)
When installing Mojave Patcher, I had come across this here (doesn't like links maybe - search dodude1 gpudisable). There's no documentation I could find as to exactly what it does and more importantly how to remove it / revert to prior state. With some poking around, it seems easily removed by:
a. sudo rm /usr/local/sbin/dGPUDisableHelper
b. sudo rm /Library/LaunchDaemons/com.dosdude1.GPUDisableHelper.plist
4. Reapply Mojave Patcher legacyVideo Patch
So far the drivers out-of-the-box with the Mojave Patcher 1.3.0 are working just fine with dimming and sleep functioning. I am still on 10.14.3 and will test that things remain okay post upgrade to 10.14.4.
I am not sure if dosdudes 10.14.4 acceleration fix is in the latest 1.3.0 patcher; I assume it is. At some earlier point in my testing, I was hanging pre-login and assumed it was due to something I had done in my various kext moves (e.g. previously installing parrotgeeks drivers). Once I upgrade I will update this post with the outcome. Sorry for those who read the 1st version of this - you were warned, it was littered with (flawed) assumptions and my meandering from failure to failure.
Cheers,
Atreides