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Changing DVMT values in BIOS


Jake Lo
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Steps to change the DVMT value (Done on Windows or WinPE)

 

/!\ Warning, some files in attachment will show as infected, you'll need to disable your antivirus temporarily

     Use at your own risk!

 
1) Universal BIOS Backup ToolKit 2.0.exe - to backup the BIOS (i.e. DellInc.-A07.rom)
2) UEFITool.exe to find the module labeled SetupPrep (not Setup as per FireWolf’s guide) and extract the PE32 image section (setup.bin)

  Update: 

  For Dell Only: Search with this GUID, right click the GUID found and select extract body. Save it as setup.bin

          899407d7-99fe-43d8-9a21-79ec328cac21

3) Universal IFR Extractor.exe to extract setup.bin to a readable text file
4) Use notepad to search for “DVMT” in the text file

    i.e. for the E7450, 2 were found at 0x432 and 0x433 but only 0x432 needs to be changed to 0x3
5) Format an USB drive to fat32 and create a folder name EFI
6) Download the EFI Shell and extract the Boot folder to EFI folder (EFI/Boot/bootx64.efi)
7) Boot system with the USB and select UEFI Boot
    At the grub prompt, enter these commands, hit enter after command, then exit and reboot
    i.e. setup_var 0x432 0x3

To verify if the value was updated, just enter setup_var 0x432 and hit enter, the value will be listed

More detailed instruction in attachment

 

/!\ Alternatively, just use Lilu.kext + Whatevergreen without having to mess with the BIOS

https://github.com/vit9696/Lilu/releases

https://github.com/vit9696/Lilu/blob/master/KnownPlugins.md

https://github.com/acidanthera/WhateverGreen/releases

 

DVMT_Tools.zip

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I was asked if the above trick was deprecated because DVMT pre-alloc can be bypassed with some Whatevergreen patches but sometimes it's still needed.

For example, you want support for 4k display, DVMT will need to be increased and the bypass won't work.

It's not recommended for everyone since it can brick your system if done incorrectly. But you can still reset it back to default by setting the BIOS to load the default or remove all the batteries for a period of time.

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