Did iMac 5K Target Display mode work?

[k30812]

Hi,

As i known apple imac no longer offer function of Target Display mode offically in NEW model and NEW macOS.
But I still like to know if the iMac5k can operate in TDM (Target Display Mode) lately.
Below is my attempt:
imac5K-1 with 2015 late i7-6700K & amd m395.
iMac5K-2 with 2015 late i5-6500 & amd m380.
both run macOS Ventura 13.6.5 with Opencore Legacy Patcher v1.4.2
iMac1 & 2 connect to eachother with a thunderbolt cable and its no work to activate the TDM.
Are There other ways or model(like macbookpro、mac mini) to succeed?

 

[joevt]

TDM has never worked with 5K iMacs.
https://support.apple.com/en-ca/105126

TDM works with iMacs from 2009 to 2014.

2009 and 2010 iMacs use DisplayPort so they'll work with anything.

For Thunderbolt iMacs (2011 to 2014), High Sierra is the best OS to use (supports audio) but later OSs may also work (without audio).

For Thunderbolt iMacs, the Thunderbolt controller requires a DisplayPort Out Adapter (use ioreg to see the adapters of a Thunderbolt controller - search for AppleThunderboltDPOutAdapter). A Mac connected to a Thunderbolt iMac will use the Thunderbolt Target Display Mode software to setup a tunnelling DisplayPort path from the Mac's Thunderbolt DisplayPort In Adapter to the iMac's Thunderbolt DisplayPort Out Adapter. A 5K Display requires two DisplayPort Out Adapters.

5K iMacs do not have Thunderbolt controllers that include a Thunderbolt DisplayPort Out Adapter. I suppose a Mac with a Thunderbolt dock could do Target Display Mode to a display connected to the Thunderbolt dock since the Thunderbolt dock has Thunderbolt DisplayPort Out Adapters. The same could be said for a Thunderbolt display which is basically just a Thunderbolt dock with a display connected to it. However, the Thunderbolt Target Display Mode software will not setup a tunnelling DisplayPort path to those adapters. I don't know if such a path is possible since the DisplayPort Out Adapter is downstream of the host controller instead of at the host controller. If it were possible, then it's a feature someone could add to Linux. Adding the feature to macOS would be more difficult since it is not open source.