ACPI

Tip

Advanced Configuration and Power Interface (ACPI) is an open standard that operating systems can use to discover and configure computer hardware components, perform power management (e.g. powering off a USB controller), auto configuration (e.g. Plug and Play, hot swapping) and status monitoring.

Manufacturers can make operating system checks, which is usually done to disable some devices and other functionality on OSes they don’t intend to support.

The main ACPI table is the DSDT (Differentiated System Description Table), defining most of the devices. Then there’s the SSDTs (Secondary System Description Tables), adding extra properties (e.g. the _PRW (Power Resources for Wake) method), extra devices, disabling some devices based on a condition, etc.

Most firmware define the devices in the DSDT and use some SSDTs to adjust values depending on the installed hardware and/or BIOS settings. If you’re interested in ACPI, you can read the ACPI Specification listed in the UEFI Forum specifications.

Downloading SSDTTime

Did you know?

In the past these SSDTs had to be written manually but now there are automated tools for this process. SSDTTime will be used by this guide.

Since SSDTTime does not have any releases and it’s a Python project, download the source code instead by clicking on Code then Download ZIP.

Running SSDTTime

After extracting the archive, Windows users should run SSDTTime.bat.

Linux users will have to open their terminal inside the extracted SSDTTime/SSDTTime-master directory then run python3 SSDTTime.py. Make sure you have Python 3 installed.

macOS users should run SSDTTime.command.

Upon launching the tool, it will automatically download iASL, which (de)compiles ACPI tables. You should then be greeted with the following screen.

Specifying the target system’s ACPI

Select option P on the target system to dump the ACPI tables needed for SSDTTime’s operations.

If you’re not running SSDTTime on the target system, select D instead to pick the folder with the ACPI tables dumped from that target machine.

The software should now show the loaded ACPI tables at the top like in the screenshot below.

Generating the SSDTs

Note

Most of these patches will only apply on macOS and should not cause any side-effects on other operating systems

Info about the options

At the time of writing, there are 12 options available

• FixHPET

  Fixes IRQ (Interrupt Request) conflicts in the ACPI tables. These conflicts can cause some hardware like sound to not work properly.

  Danger

  Do not use this option on AMD, as it may cause more harm than good (trackpad not working, etc).

• FakeEC

  Creates a fake Embedded Controller device for macOS to work properly and disables the original EC.

• FakeEC Laptop

  Creates a fake Embedded Controller device for macOS to work properly, but does not disable the original EC, because laptops need it for battery status, FN keys, etc.

• USBX

  Creates an USBX device which contains USB power properties necessary for proper functionality. This also requires a valid EC device.

• PluginType

  Sets the plugin-type property to 1 on the first CPU core, enabling X86PlatformPlugin, which allows for CPU and GPU power management (support varies). It also redefines the processors with Processor objects instead of Device objects if required, since macOS doesn’t support the newer standard.

• PMC

  Defines the PMCR device on systems that don’t have it to allow native NVRAM support.

• RTCAWAC

  Disables the new AWAC (Alarm Wake ACPI Clock) and enables the RTC (Real-Time Clock) instead.

• USB Reset

  Disables the RHUB devices in ACPI for all USB controllers to allow macOS to enumerate USB ports properly on borked ACPI systems.

• PCI Bridge

  Defines the PCI bridges for a device path specified as some devices might not have their PCI bridges defined which will make OpenCore unable to inject properties using the DeviceProperties key in the configuration.

• PNLF

  Creates a fake PNLF device with an user-selectable _UID (basically the profile it uses) to allow for native brightness control on laptops.

  Danger

  At a first glance it may appear as if it supports AMD laptops, but it is not the same as the one in the NootedRed page. Use the one in the aforementioned page instead.

• XOSI

  Spoofs the operating system to Windows, allowing any peripherals locked behind non-macOS to be active on macOS.

• Fix DMAR

  Removes Reserved Memory Regions from the DMAR table. It is required to get some devices like Intel I225-based ethernet controllers on Intel systems.

  Danger

  If you are already using macOS 12.2.1 and below and an Intel I225-based ethernet controller, you will need to remove e1000=0 or dk.e1000=0 from your boot args after doing this.

All systems must choose the below

• USBX,

  Choose the default option (B key).

• RTCAWAC,

  If it says you don’t need it, skip this SSDT.

• PluginType,

• and USB Reset.

AMD desktops must also choose the following

• FakeEC.

AMD laptops must also choose the following

• FakeEC Laptop,

• XOSI,

  Choose default (A key)

• and any backlight-related SSDTs required in the NootedRed page.

Example procedure

Based on an ASRock B550m Phantom.

Copying the AML files from the Results folder

The Results folder will look similar to the below after you’re done.

Now, copy all the files that start with SSDT and end in .aml inside of the root of the Results folder to Drive/EFI/OC/ACPI.

Merging the OC patches using PatchMerge

Finally, merge patches_OC.plist by using the PatchMerge script included with SSDTTime. Run it the same way as SSDTTime.

Press 1 to select the Config.plist created in an earlier step, then drag and drop your Config.plist onto the window, and press enter.

Afterwards, press 2 to start the merging process.

The modified Config.plist with the patches merged in will appear in the Results folder.

Check that it’s okay, then replace your original Config.plist with the newly generated one.