A treatise on bracing with its application to bridges and other structures of wood or iron

The parameter n is settable per port. A process can give the ability to send to (or receive from) one of its ports to another process. This permission takes the form of a capability, and includes not only a pointer to the port, but also a list of rights that the other process has with respect to the port (e.g., SEND right). Once this permission has been granted, the other process can send messages to the port, which the first process can then read. All communication in Mach uses this mechanism. Mach does not support a full capability mechanism; ports are the only objects for which capabilities exist. 8.1.4. The Mach BSD UNIX Server As we described above, the Mach designers have modified Berkeley UNIX to run in user space, as an application program. This structure has a number of significant advantages over a monolithic kernel. First, by breaking the system up into a part that handles the resource management (the kernel) and a part that handles the system calls (the UNIX server), both pieces become simpler and easier to maintain ...»