We think it's caused by IOUSBFamily.
I'm able to boot the Mojave Installer and the Mojave Recovery Partition on MP3,1. Does it not use IOUSBFamily? I'm gonna see if I can put the Recovery volume on a regular partition and see if it boots and also inspect what kext's are up and running, if possible. I was able to crack the DMGs by accident went installing beta 1 on an internal PCIe SSD that does not get direct access to the Mac's EFI. Will try to the same with Beta 2 and see if I can put its recovery partition on another drive that I can add and remove stuff from and maybe at least get system profiler to do something and see what the Mac Pro 3,1 can do on a sub Mojave system.
I'm able to boot the Mojave Installer and the Mojave Recovery Partition on MP3,1. Does it not use IOUSBFamily? I'm gonna see if I can put the Recovery volume on a regular partition and see if it boots and also inspect what kext's are up and running, if possible. I was able to crack the DMGs by accident went installing beta 1 on an internal PCIe SSD that does not get direct access to the Mac's EFI. Will try to the same with Beta 2 and see if I can put its recovery partition on another drive that I can add and remove stuff from and maybe at least get system profiler to do something and see what the Mac Pro 3,1 can do on a sub Mojave system.