No need to connect any TB device before booting the system. The TBEX 3 get's fully automatically initialised and implemented by OSX as soon a TB or TB XHC USB device will be connected to the already operational macOS system.
>>> https://youtu.be/JSNp75UOfq4 <<<
Give it a try with my SSDT-X299-iMacPro.aml properly adapted to your system
Full TB Hot Plug Functionality!
Maybe you also need an update to SMBIOS iMacPro1,1 in addition?
Hi @KGP-iMacPro, finally after more than a month some progress!
Unfortunately this is not the definitive answer, but it poses other questions.
What I did not say yesterday, is that once the THB_C cable is removed the Thunderbolt PCI card is not loaded by the system at startup.
But if I have a device connected and turned on before boot the PCI card is recognized and loaded correctly, but not only, in this way you have the hotplug of all devices!
To make it work, add "PCI-Thunderbolt One" to PXSX/BR1A. It works either with Arbitrary inject or with _DSM method on SSDT (better because the devices can be implemented on the PCI system info).
I use a Thunderbolt dock that turns on when I turn on the computer (to be precise, since I use Fix Shutdown, never turns off like my USB devices), and then the Thunderbolt PCI card is charged every time the computer is started and all the devices after the dock are hotpluggable.
Based on the original Apple SSDT of an iMac18,3, I realized this: SSDT-TB3 V3.zip (Updated version) However I do not know if it works correctly on both Thunderbolt ports and USB-C devices. I will do some more tests when we have the final solution.
Obviously as I said, this is not a solution, but it makes clear that the problems with the hotplug derive from the functions that add the THB_C cable, so we are faced with two ways: 1- Finding the way to make the PCI card load from the system even without a connected THB_C cable 2- Understand what features this cable provides and whether it can be found in ACPI paths to include it in the SSDT
I think I found a way to use an nvidia helper card...
On the internet they say if you cut the end of the PCI-e x1 slot, an x16 PCI-e video card will work in it.
I have an 8600gt which works OOB in high sierra, but I'm not sure if I can set it as primary since in bios I have only PEG/PCI or PCI/PEG primary video.
Maybe I can set it as primary from DSDT or clover?