Microkernels should support passive objects

We believe that a passive object model, in which the active entities or threads migrate between passive objects, is more appropriate than an active object model, as the basic structure of a microkernel-based operating system. A passive object model provides enhanced performance and simplicity because it is more closely matched to the basic nature of microprocessors and the requirements of applications. It also provides more functionality by making the flow of control between objects a first-class abstraction which can be examined, manipulated, and used to carry information about the operation in progress