I did some debugging about 8 years ago in SmartOS. There were some processing that were running for way too long without using the cpu. I ended up using kdbg to

I did some debugging about 8 years ago in SmartOS. There were some processing that were running for way too long without using the cpu. I ended up using kdbg to trace where the processes were hung. I had to jump between different processes to trace the door calls. There was no unified stack in one process that spanned multiple address spaces, and the calling threads were paused. So, yes. The documentation in right, the calling thread is paused while a different one is used one the other side of the door.