Pages and nodes

The microkernel provides some fixed number of pages and nodes. There are typically many thousands of pages and nodes. A page holds 4096 bytes of data and a node has sixteen slots. A node also has an associated process-running predicate which is TRUE if and only if the node is the distinguished node of a running domain. Pages and nodes are microkernel-implemented objects and they are accessed by keys. Permanent state-bearing objects are ultimately built of pages and nodes. Pages and nodes carry all of the permanent state of the system. Pages and nodes are swapped by the microkernel to provide a single-level store. Pages and nodes are the only primitive microkernel objects provided in large numbers. The checkpoint-restart mechanism and checkpoint to magnetic tape deal only with pages and nodes.

A node key designates a node and provides authority to retrieve keys from the node or to place keys into the node. A fetch key also designates a node but may be used only to retrieve keys from the node.

A page may be designated by read-write and read-only page keys.