# Legacy Nvidia Patching

  • Please note this page is more of an info dump, we won't be going to too great of detail on setup though we plan to expand this page more for it.

With legacy Nvidia GPUs, macOS has difficulties enabling acceleration due to many missing properties. To work around this, we can inject properties into IOService for macOS to easily interpret.

To start off, we'll be assuming the following:

  • macOS has already been installed in some way
    • We need macOS installed to determine certain properties
  • Your GPU is either Fermi or older
    • Kepler and newer do not need Device Property injection
  • Lilu and WhateverGreen are loaded
    • verify by running kextstat | grep -E "Lilu|WhateverGreen"

# Finding the GPU pathing

First lets grab gfxutil (opens new window) and run the following:

path/to/gfxutil -f display

This should spit out something like the following:

67:00.0 10DE:0A20 /PC02@0/BR2A@0/GFX0@0/ = PciRoot(0x2)/Pci(0x0,0x0)/Pci(0x0,0x0)

What we care about is the PciRoot section, as this is where our GPU is located and where we'll be injecting our properties:

PciRoot(0x2)/Pci(0x0,0x0)/Pci(0x0,0x0)

# Building our DeviceProperties

With Nvidia GPUs, there's actually not too many properties required for setup. The main ones that are recommended are the following:

Property Value Comment
model ex. GeForce GT 220 GPU model name, cosmetic
device_type NVDA,Parent Always set as NVDA,Parent
VRAM,totalsize ex. 0000004000000000 Sets VRAM size
rom-revision Dortania Property must exist, however the value can be anything
NVCAP ex. 0500000000000F00000000000000000F00000000 sets display properties used by macOS, more info below
@0,compatible NVDA,NVMac Always set as NVDA,NVMac
@0,device_type display Always set as display
@0,name NVDA,Display-A Always set as NVDA,Display-A
@1,compatible NVDA,NVMac Always set as NVDA,NVMac
@1,device_type display Always set as display
@1,name NVDA,Display-B Always set as NVDA,Display-B

And to calculate the properties few properties:

# model

Technically cosmetic, however macOS expects this entry so we'll provide it. The format is as follows:

GeForce [Device Name]
# Example
GeForce GT 220

# VRAM,totalsize

Amount of VRAM present on your card, in hexadecimal.

For this example, lets convert 1024MB to hexadecimal:

# Convert 1024MB Megabytes to Bytes
echo '1024 * 1024 * 1024' | bc
 1073741824

# Convert from decimal to hexadecimal
echo 'obase=16; ibase=10; 1073741824' | bc
 40000000

# Hexswap so it can be injected correctly
# ie. swap in pairs
40000000 -> 40 00 00 00 -> 00 00 00 40

# Pad the value to 8 bytes with 00 at the end
00 00 00 40 00 00 00 00

# And you're done
VRAM,totalsize = 0000004000000000

# rom-revision

Simply can be any value, however the property must exist as some GPUs fail to initialize without it(ex. GT 220's)

rom-revision = Dortania

# NVCAP

This is where the fun comes it, as we'll now need to calculate the NVCAP value. Thankfully for us, one of our Developers has created a tool to automate the process: NVCAP-Caluclator (opens new window)

To use this program, simply grab your VBIOS(TechPowerUp hosts most VBIOS (opens new window)) and run NVCAP-Calculator:

git clone https://github.com/1Revenger1/NVCAP-Calculator
cd NVCAP-Calculator
npm install
npm run run

Once its running, you should see the following:

Next, enter 1 and give it your VBIOS

Now press enter, and return to the main menu. Once there, enter 3 to take you to the NVCAP calculation page.

Here you can see the connectors that NVCAP-Calculator was able to find. Each Display may represent multiple DCB Entries, such as DVI (normally represented as two entries) or duplicate DCB entries. The goal here is to assign each display to a head. Each head can only output to one display at a time. For example, if your using 2 DVI ports, each should be on their own head to have proper dual monitor support.

Note that some displays may be assigned automatically. An LVDS display will be put on it's own head automatically, and TV displays will be put on the TV head automatically.

To assign a display to a head, you type the number of the display then the number of the head. For example, typing in 1 1 results in:

You can type in 1 1 again to remove the display from the head. Once done, it should look something like this:

You should set the NVCAP values directly below the heads now as well.

NVCAP Value Details Example Command
Version 04 for 7 series and older, 05 for 8 series and newer n1 04
Composite 01 for S-Video, 00 otherwise n2 to toggle
n2 true
Script based Power/Backlight 00 ony useful for genuine MacBook Pros n3 0
Field F (Unknown) 0F for 300 series and newer, otherwise 07 n4 0x0f

Once done, enter in c to calculate the NVCAP value

You now have your NVCAP value!

NVCAP: 05000000 00000300 0c000000 0000000f 00000000

For those who are wanting a break down on how to calculate the NVCAP value:

NVCAP Table

Info based off of WhateverGreen's NVCAP.bt file (opens new window)

NVCAP Bit Name Comment
Byte 1 NVCAP Version 04 for 7 series and older, 05 for 8 series and newer
Byte 2 Laptop with Lid 01 for true, 00 otherwise
Byte 3 Composite 01 for S-Video, 00 otherwise
Byte 4 Backlight 01 for Tesla V1 with Backlight, otherwise 00 for newer GPUs regardless of screen type
Bytes 5+6 TVDCBMask 00 00, relates to DCB entry 5
Bytes 7+8 Head0DCBMask 00 00, see below
Bytes 9+10 Head1DCBMask 00 00, see below
Bytes 11+12 Head2DCBMask 00 00, non-applicable for Fermi and older
Bytes 13+14 Head3DCBMask 00 00, non-applicable for Fermi and older
Byte 15 ScriptBasedPowerAndBacklight 00, only relevant for genuine MacBook Pros
Byte 16 Unknown 0F for 300 series and newer, otherwise 07
Byte 17 EDID 00
Byte 18 Reserved 00
Byte 19 Reserved 00
Byte 20 Reserved 00

# Cleaning up

Now that we've gotten all our properties, we can now add em up and place them in our config.plist:

PciRoot(0x2)/Pci(0x0,0x0)/Pci(0x0,0x0)

model          | String | GeForce GT 220
device_type    | String | NVDA,Parent
VRAM,totalsize |  Data  | 0000004000000000
rom-revision   | String | Dortania
NVCAP          |  Data  | 05000000 00000300 0c000000 0000000f 00000000
@0,compatible  | String | NVDA,NVMac
@0,device_type | String | display
@0,name        | String | NVDA,Display-1
@1,compatible  | String | NVDA,NVMac
@1,device_type | String | display
@1,name        | String | NVDA,Display-B

Open your config.plist and head to DeviceProperties -> Add, next create a new child with the name of your GPU's path(ie the one with gfxutil). Then, finally add the properties as children to the PciRoot. You should end up with something similar:

Last Updated: 11/8/2020, 6:18:39 PM