I am studying Solaris and Linux and am viewing Kernel Level Threads (KLTs) as the fundamental entity that can be scheduled and dispatched by the OS. I know that a multi-threaded OS must store thread execution context and provide mechanisms to schedule and dispatch KLTs, and that kernel level threads handle interrupts, system calls, and provide an interface to the CPU as a resource at the user-kernel interface. I am not clear on what services are necessary to support KLTs in a multi-threaded OS.
I cannot determine if there is a core kernel process that is necessary to support all KLTs, or if KLTs run interdependently as the base-level of computing. I would like to understand what minimum set of operations (resource allocation, scheduling) is necessary to support an OS with KLTs.
I have looked at Tanenbaums Tanenbaum's discussion of threads in his distributed systems book, Understanding the Linux Kernel, and MultiThreading the SunOS kernel but I cannot find an answer to my question.
I believe that answering the question -- What Operating System services are necessary to support kernel-level threads? -- will help me understand how KLTs are implemented.