This paper describes PRISM, a distributed sharedmemory architecture that relies on a tightly integrated hardware and operating system design for scalable and reliable performance. PRISM's hardware provides mechanisms for flexible management and dynamic configuration of shared-memory pages with different behaviors. As an example, PRISM can provide configure individual sharedmemory pages in both CC-NUMA and Simple-COMA styles, maintaining the advantages of both without incorporating any of their disadvantages. PRISM's operating system is structured as multiple independent kernels, where each kernel manages the resources on its local node. PRISM's system structure minimizes the amount of global coordination when managing shared-memory: page faults do not involve global TLB invalidates, and pages can be replicated and migrated without requiring global coordination. The structure also provides natural fault containment boundaries around each node because physical addresses d...