smbios and drm's ( Why?)

[aikido14]

Hi, i have build a system as close as much as latest iMac Intel : msi z490 motherboard, intel 10500 cpu and amd 5500XT gpu.
This looks very muche like iMac 20.1 hardware.
Whatever system i have tried on ( from Catalina to Sonoma) if i run this system with iMac 20.1 SMBIOS it won't read AppleTV videos ( except from trailers) nor iTunes ( or Music app) Videos. All the rest is fine, DVD playback etc..
So i switched to iMac Pro SMBIOS and this resolves the problem.
Can someone tell me why, I need to understand ! And is there a way to get this kind of iMac 20.1 hardware work like it should regarding this drm issue ?
TIA

 

[jaymonkey]

if i run this system with iMac 20.1 SMBIOS it won't read AppleTV videos ( except from trailers) nor iTunes ( or Music app) Videos. All the rest is fine, DVD playback etc.. So i switched to iMac Pro SMBIOS and this resolves the problem.

Can someone tell me why, I need to understand.

@aikido14,

Any genuine Apple Mac (EG: iMac20,X) that uses an Intel Desktop or Laptop class CPU has custom Apple firmware burned into the IGPU microcode that is specifically designed for Apple DRM validation. A PC based Hackintosh that uses a standard off-the-shelf CPU does not have this special source Apple firmware burned into the IGPU so DRM will not work.

For a while it was possible to negate this on some system by use of the shikigva boot argument which enabled a WhatEverGreen workaround but unfortunately this no longer works on more recent versions of MacOS.

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A genuine iMacPro uses an Intel Xeon Workstation class CPU which does not have a built-in IGPU therefore it uses the AMD dGPU for DRM validation and codec decode, in this case the DRM validation code is written into the MacOS AMD device drivers and VROM which are loaded by the MacOS kernel at boot time so as long as you use a supported dGPU in a Hackintosh build and use the iMacPro SMBIOS DRM should work.

It's also very easy to force the above behaviour when using a non iMacPro SMBIOS such as iMac20,X by simply disabling the IGPU in the BIOS, this will (in most cases) cause MacOS to fall back to a supported AMD dGPU for DRM validation and codec decode. It should be noted however that disabling the IGPU on a iMacX,X SMBIOS will stop certain Apple specific features such as Sidecar and Airplay from working but this is also true when using the iMacPro SMBIOS as the iMacPro uses the T2 Chip for such features.

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I wrote about all of the above in more detail back in 2018 in my Lilu & Plugin's guide here :-

An iDiot's Guide To Lilu and its Plug-ins

An iDiot's Guide To Lilu and its Plug-in's Last Update: 22nd Jan 2021 (Add note about OpenCore config.plist modifications) About this Guide Note: This guide was written when Clover was the boot loader of choice as such the config.plist examples in this guide are mostley Clover specific ... if...

www.tonymacx86.com

Cheers
Jay

 

[aikido14]

thank you very much for having taking the time for explanation !
Of course one may think it doesn't change much in the end
... as for me understanding changes a lot