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@khronokernel @dhinakg
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Improve GPU performance and remove nullcpupowermanagement.kext

Last edited: January 23, 2020

What you'll need:

Warning

The HPET patch can break Windows booting through OpenCore, do not use this guide unless you're ok with this

1. Removing nullcpupowermanagement.kext:

Remove NullCPUPowerManagement.kext and add the following patch to Kernel -> Patch:

Find: D0 05 00 00 84 C0 74 46 E8

Replace: D0 05 00 00 84 C0 EB 46 E8

Identifier: com.apple.driver.AppleIntelCPUPowerManagement

Enabled String YES
Count Number 1
Identifier String com.apple.driver.AppleIntelCPUPowerManagement
Limit Nuber 0
Find Data D005000084C07446E8
Replace Data D005000084C0EB46E8

Do not reboot yet, you need to follow the entire guide first

2. Create an plugin-type=1 SSDT:

Now the fun begins, we'll be grabbing our SSDT-PLUG and converting it to our system. The specific part we're wanting to adapt is CPU0 as not all DSDTs have theirs starting with CPU0, for us AMD usually exposes this under the CPUSSDT. Generally, AMD uses C000 but others can be P000 so you'll want to edit all mentions of CPU0 to your value.

Easiest way to check what

Now edit your SSDT with MaciASL, then export it via File -> SaveAs -> ACPI Machine Language. Don't forget to add this SSDT to both your config.plist under ACPI -> Add and add the file to EFI/OC/ACPI.

Don't forget that compiled SSDTs have a .aml extension(Assembled)

3. Verifying HPET is on

This is important as this is required for SSDT-PLUG to work correctly, many systems already have it enabled but some need it forced on. To verify yours, open IORegistryExproler and search for HPET. Look to the right and try to see what properties this device has, we want it to have _STA = 0xF, if not then we want to enable it.

  • SSDT-XOSI.aml
    • Prebuilt so no need to compile, just add to config.plist and EFI/OC/ACPI
  • _OSI to XOSI rename under ACPI -> Patch:
Enabled String YES
Count Number 0
Limit Nuber 0
Find Data 5f 4f 53 49
Replace Data 58 4f 53 49

4. Creating the AGPM injector kext

Now open up AGPMInjector and run it, then add the kext to both your config.plist under kernel -> Add and into EFI/OC/Kexts.

And voila! you're done!

5. Verifying your work

Open IORegistryExplorer and search for your CPU, then verify that both X86PlatformPlugin and AGPM are connected. If so, then you have proper GPU power management and therefore slightly improved performance.

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