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[GUIDE] General Framebuffer Patching Guide (HDMI Black Screen Problem)

Hi @CaseySJ Thanks for your reply, please see my responses below.

1. You are currently using iMac18,1 and the SMBIOS section of config.plist is not fully filled out. Have you tried iMac18,2 (Retina 4K) or even iMac18,3?

(1) Yes I have tried both 18,2 and 18,3, both are unusable - flickers, artifacts and the screen unresponsiveness.

2. Are you driving the LG monitor with DisplayPort? Your Platform ID is set to 0x59120000 with all connectors as DP, so HDMI most likely does not work. Or are you using a DisplayPort to HDMI adapter?

(2) I am using DisplayPort, will not use the other connectors.

3. What the model number of the LG monitor? Is it flat screen television or a computer monitor?

(3) Computer monitor is the LG 27UK850-W. Full 4K works ok on Windows 10

4. Please post a screenshot of: System Information --> Graphics/Displays. This will provide more information about the monitor and the properties of the monitor.

(4) Attached

5. The i5-7500T is a Kaby Lake processor, so the Azul Framebuffer patch in Kernel and Kext Patches will not have an effect. It's okay to leave that in place, but probably better to check the Disable flag.

(5) Thanks, will do.
 

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Hi @CaseySJ Thanks for your reply, please see my responses below.

(1) Yes I have tried both 18,2 and 18,3, both are unusable - flickers, artifacts and the screen unresponsiveness.

(2) I am using DisplayPort, will not use the other connectors.

(3) Computer monitor is the LG 27UK850-W. Full 4K works ok on Windows 10

(4) Attached

(5) Thanks, will do.
Here's a somewhat counterintuitive suggestion based on the following post:
  • Set Platform ID to 0x3E9B0007
  • Set Device ID to 0x3E9B
Remember to enter these values in reverse byte order in Clover Configurator --> Devices --> Properties:
  • Platform ID: 07009B3E
  • Device ID: 9B3E
Let's see what happens...
 
Just wandering if the mods in the OP will make it possible to use 2 ports (DP) on my RX580 simultaneously with 1 (properly patched framebuffer of cause) HDMI port on the mobo - IGPU that is?
Tried that just for kicks on my Skylake build, but so far without success. Presently running the IGPU headless.
Appreciate some feedback.
 
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Here's a somewhat counterintuitive suggestion based on the following post:
  • Set Platform ID to 0x3E9B0007
  • Set Device ID to 0x3E9B
Remember to enter these values in reverse byte order in Clover Configurator --> Devices --> Properties:
  • Platform ID: 07009B3E
  • Device ID: 9B3E
Let's see what happens...

Whaoo! Looks like we are almost there

I added platform ID 0x3E9B0007 and device ID 0x3E9B, rebooted but got a kernel panic - see image and plist

I tried the second time adding only the Platform ID 0x3E9B0007 (without adding the device ID 0x3E9B) and was able to successfully boot into 3840X2160 but with only 2 scaled resolutions; 384X2160 and 1920X1080 with 31MB of VRAM

Did I mess up the device-id on my first try - config.plist attached.

I appreciate your time and help.
 

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  • second_attempt_without_device_ID.png
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  • config_with_p-ID_and_d-ID.plist
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Whaoo! Looks like we are almost there

I added platform ID 0x3E9B0007 and device ID 0x3E9B, rebooted but got a kernel panic - see image and plist

I tried the second time adding only the Platform ID 0x3E9B0007 (without adding the device ID 0x3E9B) and was able to successfully boot into 3840X2160 but with only 2 scaled resolutions; 384X2160 and 1920X1080 with 31MB of VRAM

Did I mess up the device-id on my first try - config.plist attached.

I appreciate your time and help.
Looks promising! The entry is correctly specified, however:
  • Try again without the stolenmem parameter.
  • Try also iMac14,2
(Make one change at a time.)
 
Looks promising! The entry is correctly specified, however:
  • Try again without the stolenmem parameter.
  • Try also iMac14,2
(Make one change at a time.)

Unfortunately none of these worked:

  • 0x3E9B0007/0x3E9B + iMac14.2
  • 0x3E9B0007/0x3E9B Without stolenMem
 
Just wandering if the mods in the OP will make it possible to use 2 ports (DP) on my RX580 simultaneously with 1 (properly patched framebuffer of cause) HDMI port on the mobo - IGPU that is?

@Henties,

The method posted in this guide is for patching IGPU framebuffer only.

If you need to patch the AMD framebuffer connector types then you need to apply a patch to the AMD driver.
See this guide for more info :-


See section 3 for specifics on AMD framebuffer patching.

Cheers
Jay
 
@Henties,

The method posted in this guide is for patching IGPU framebuffer only.

If you need to patch the AMD framebuffer connector types then you need to apply a patch to the AMD driver.
See this guide for more info :-


See section 3 for specifics on AMD framebuffer patching.

Cheers
Jay
@jaymonkey Thank you for your response. My Asus RX580 Strix is and has been working OOB without any issues whatsoever, with framebuffer patching never having been required. My onboard Intel IGPU 530 has been configured as a headless device in the "Devices" section of the Skylake config.plist with the connectorless AAPL.lg-platform-id 01001219 and device-id of 12190000 being used. Everything works perfectly indeed. I am just wandering whether the onboard IGPU could be put to better use and drive a monitor, or 2 for that matter, as well. I realize that Apple does not use such a configuration for it's own machines which sport a dGPU as well as an IGPU. Therefore this idea of mine, which is perhaps even doable, requires one to venture into totally uncharted territory. Hoping, with my enquiry in this thread, that I could actually connect with somebody that has actually already tried this, with findings which could prove tremendously invaluable for my own endeavors in this regard.

Greetings

Henties
 
@Henties,

I've run IGPU in a non headless configuration along side dGPU in the past but there is absolutely no performance benefit as even a low spec dGPU will do a much better job than a IGPU. The only reason to do it is if your dGPU cant drive all the monitors your need but it does somewhat confuse MacOS as it's a non standard configuration and you may actually have reduced MacOS performance (depending SMBIOS used).

Best to run all your monitors of the dGPU if possible and let MacOs use the IGPU in headless mode for light compute tasks which is how MacOS is designed to run.

Cheers
Jay
 
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@Henties,

I've run IGPU in a non headless configuration along side dGPU in the past but there is absolutely no performance benefit as even a low spec dGPU will do a much better job than a IGPU. The only reason to do it is if your dGPU cant drive all the monitors your need but it does somewhat confuse MacOS as it's a non standard configuration and you may actually have reduced MacOS performance.

Best to run al your monitors of the dGPU and keep IGPU for light MacOS compute tasks in headless mode which is how MacOS is designed to run.

Cheers
Jay
@jaymonkey Thanks, your feedback is much appreciated.

Greetings

Henties
 
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