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Fixing CFG Lock

This guide is only recommended for users who have already installed macOS, for users who are installing for the first time enable AppleCpuPmCfgLock and AppleXcpmCfgLock under Kernel -> Quirks

  • Note that this guide is only applicable for Intel users. AMD users don't have any type of CFG Lock

What is CFG-Lock

CFG-Lock is a setting in your BIOS that allows for a specific register(in this case the MSR 0xE2) to be written to. By default, most motherboards lock this variable with many even hiding the option outright in the GUI. And why we care about it is that macOS actually wants to write to this variable, and not just one part of macOS. Instead both the Kernel(XNU) and AppleIntelPowerManagement want this register.

So to fix it we have 2 options:

1. Patch macOS to work with our hardware

  • This creates instability and unnecessary patching for many
  • The 2 patches we use for this:
    • AppleCpuPmCfgLock for AppleIntelPowerManagement.kext
    • AppleXcpmCfgLock for the Kernel(XNU)

2. Patch our firmware to support MSR E2 write

  • Very much preferred, as avoids patching allowing for greater flexibility regarding stability and OS upgrades

Note: Penyrn based machines actually don't need to worry about unlocking this register

Checking if your firmware supports CFG Lock unlocking

Before proceeding with the rest of this guide, you'll first need to check if your firmware supports CFG Lock unlocking. To check it, you can proceed into two ways:

  1. Use the DEBUG version of OpenCore and check what the log says about CFG Lock
  2. Use a tool called VerifyMsrE2 which will speed up the whole checking process

Checking via OpenCore logs

For users who prefer using DEBUG release, you'll want to enable the DEBUG variant of OpenCore with Target set to 67 and boot OpenCore. This should provide you with a file in the format of opencore-YYYY-MM-DD-hhmmss.txt on the root of the drive.

Within this file, search for OCCPU: EIST CFG Lock:

OCCPU: EIST CFG Lock 1

If it returns 1, then you proceed with this guide here: Disabling CFG Lock.

Otherwise(ie. 0), no reason to continue and you can simply disable Kernel -> Quirks -> AppleCpuPmCfgLock and Kernel -> Quirks -> AppleXcpmCfgLock.

Checking via VerifyMsrE2

To start, download VerifyMsrE2 and add this tool inside EFI/OC/Tools and config.plist(this can be done with ProperTree's snapshot function(ie. Cmd+R)). Next, boot OpenCore and select the VerifyMsrE2.efi entry. This should provide you one of the following:

  • CFG-Lock is enabled:
This firmware has LOCKED MSR 0xE2 register!
  • CFG-Lock is disabled:
This firmware has UNLOCKED MSR 0xE2 register!

For the former, please continue here: Disabling CFG Lock.

For the latter, you don't need to do any CFG-Lock patches and can simply disable Kernel -> Quirks -> AppleCpuPmCfgLock and Kernel -> Quirks -> AppleXcpmCfgLock.

Disabling CFG Lock

So you've created the EFI folder but you can't still boot without unlocking before CFG Lock. In order to do this you'll need the following:

Inside your EFI/OC/Tools folder and config.plist, add the following tool(this can be done with ProperTree's snapshot function(ie. Cmd+R)):

And some apps to help us out:

And the final part, grabbing your BIOS from the vendors' website.

Now the fun part!

Turning off CFG-Lock manually

Please note that the only firmwares that can be directly opened by UEFITool are ASUS, MSI and ASRock. Other firmwares need a special procedure which we'll not directly cover into this guide. For Dell firmwares, please refer to dreamwhite's guide

  1. Open your firmware with UEFITool and then find CFG Lock as a Unicode string. If nothing pops up then your firmware doesn't support CFG Lock, otherwise continue on.

  1. You'll find that this string is found within a Setup folder, right-click and export as Setup.bin (or even Setup.sct)

  2. Open your setup file with ifrextract and export as a .txt file with terminal:

    path/to/ifrextract path/to/Setup.bin path/to/Setup.txt

  3. Open the text file and search for CFG Lock, VarStoreInfo (VarOffset/VarName): and note the offset right after it (ie: 0x5A4)

  1. Run the Modified GRUB Shell and write the following command where 0x5A4 is replaced with the value you've previously extracted:

    setup_var 0x5A4

If you get an error such as error: offset is out of range run the following command:

setup_var2 0x5A4

Just as before, if you still get error: offset is out of range you'd need to use this command:

setup_var_3 0x5A4

If you don't get any type of error, write the command which doesn't lead to error: offset is out of range (e.g. setup_var_3 0x5A4) and write 0x00 after it:

setup_var_3 0x5A4 0x00

At this point, run either reset in the shell or simply reboot your machine. And with that, you should have CFG Lock unlocked! To verify, you can run over the methods listed at Checking if your firmware supports CFG Lock unlocking to verify whether the variable was set correctly then finally disable Kernel -> Quirks -> AppleCpuPmCfgLock and Kernel -> Quirks -> AppleXcpmCfgLock.

  • Do note that variable offsets are unique not just to each motherboard but even to its firmware version. Never try to use an offset without checking.

And you're done! Now you'll have correct CPU power management

  • Note: Every time you reset your BIOS you will need to flip this bit again, make sure to write it down with the BIOS version so you know which.

  • Note 2: Some OEMs like Lenovo may have the variable set but cannot unlock it without physically modding the BIOS, for these situations you may need to use a tool like RU: CFG LOCK/Unlocking - Alternative method