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I finally figured out what the problem was for my other question, which was sadly closed even though it had a clear problem to solve. Briefly, the problem is that my dGPU 750M in my late 2013 15" MacBook Pro gets stuck in a high power state, pulling 17W at idle instead of 3W. I installed Catalina fresh on an external drive and that fixed my dGPU being stuck in a higher power state.

I compared the system kernel extensions loaded on the fresh Catalina install with those loaded on the problematic install and made a list of all the kexts that did not load in the problematic Catalina install. The problem is that the system is not loading these kexts from /system/library/extensions:

IOPlatformPluginFamily.kext/contents/plugins/x86platformplugin.kext IOPlatformPluginFamily.kext/contents/plugins/ioplatformpluginlegacy.kext IOPlatformPluginFamily.kext/contents/plugins/acpi_smc_platformplugin.kext IOPlatformPluginFamily.kext/contents/plugins/x86platformshim.kext applegraphicspowermanagement.kext
appleplatformenabler.kext

In fact my issue is fixed by simply just loading x86platformplugin.kext:

sudo kextload IOPlatformPluginFamily.kext/contents/plugins/x86platformplugin.kext

However it's probably best to load all of those that are present on a clean Catalina install and not present on my problematic install.

After loading x86platformplugin.kext manually, toggling on the 750M dGPU results in it being able to use its low power state, consuming just 3W at idle compared to 17W otherwise.

Why aren't these kexts loading on my problematic Catalina install? How do I get these kexts to load automatically after reboot?

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  • Have you tried doing a clean install of Catalina? It sounds like you did an in-place upgrade which I always advise against.
    – Allan
    Commented Jul 15, 2020 at 0:23
  • I installed a completely separate and fresh Catalina install on the external harddrive. That proved there is something wrong with the broken install on the internal SSD since it fixed the issue. I diagnosed the problem on the broken install to the kexts not loading.
    – Flyview
    Commented Jul 15, 2020 at 0:28
  • I know that. Thus my question.
    – Allan
    Commented Jul 15, 2020 at 0:29
  • Well yes, clearly if I did a clean install that would fix the problem, but I'd rather try and find a way to load the kexts properly so I don't have to go through re-installing all my programs and settings.
    – Flyview
    Commented Jul 15, 2020 at 0:30
  • I don’t recommend in-place upgrades because you end up with issues like what you’re seeing. Migration assistant will address your reinstall needs, but with something like Catalina that’s so vastly different from older releases, reinstalling apps is a good idea especially when it comes to system stability.
    – Allan
    Commented Jul 15, 2020 at 0:54

1 Answer 1

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If a simple terminal command is working for you, then you can create a logon script as an ugly hack and use it for a few months.

The next macOS will release in the fall so it might fix things for you.

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  • Can you please post how to create this script? Do you recommend doing an absolutely clean install for Big Sur? Can you restore just data with Time Machine but not installed apps? Or would restoring apps be fine? As long as nothing touches the system files from the backup...
    – Flyview
    Commented Jul 15, 2020 at 20:02
  • With an unexplained glitch a clean install is the way to go. Because if the situation becomes worse, it will usually happen at the worst possible time.
    – Dirk
    Commented Jul 16, 2020 at 0:40
  • Time Machine allows for the restore of just your files, but in your case the apps can be restored as well. A logon script requires the Terminal and 5-10 minutes. How comfortable are you with Terminal?
    – Dirk
    Commented Jul 16, 2020 at 0:52
  • See this link on how to load a kext on login.
    – Dirk
    Commented Jul 16, 2020 at 1:14

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