CFG Lock

[pmdevita]

Taking some notes about the CFG Lock here

Removing the CFG Lock enables better compatibility with Mac and better CPU and power management. If you are undervolting the laptop (and you probably should), the process is nearly identical. This is done by booting a modified version of the Grub EFI shell and changing the variables controlling the locks.

Sources:

• https://dortania.github.io/OpenCore-Desktop-Guide/extras/msr-lock.html
• https://www.reddit.com/r/Dell/comments/fzv599/xps_7590_160_uefi_unlock_undervolting_and_remove/

Tools:

• Dell PFS Extract
• UEFITool
• Universal IFR Extractor

To boot the modified Grub shell, you can mount your EFI, create a folder in the EFI folder called GrubMod, and then place the grub mod EFI file there. Then, boot to your BIOS, add the file to your boot list, and then boot to it.

Here is the variable for the CFG Lock in a few versions of the BIOS.

• 1.6.0 - 0x6ED
• 1.9.1 - 0x6ED

Here is the variable for the overclocking (and underclocking) lock in a versions of the BIOS.

• 1.6.0 - 0x789
• 1.9.1 - 0x789

After booting, you run the command setup_var_3 <variable> 0x00 where <variable> is the hexadecimal number corresponding to your BIOS version and the lock you are removing. So, for example, if I am on BIOS 1.9.1, I would run two commands setup_var_3 0x6ED 0x00 and setup_var_3 0x789 0x00 to disable my CFG and overclocking locks respectively.

It is incredibly important that one uses the correct variable for their BIOS version as editing the wrong variable could result in bricking the computer. You may want to follow the instructions in the sources and double check that I found the right variables for the BIOS version you are running.

[pmdevita]

Idle drain has not improved, I'm still losing 1%/5min or so. The CFG lock is definitely off now, I'm not sure if I was supposed to see an improvement in battery life or how much.

[pmdevita]

Moving to Wiki