Avaya Technology LLC

Donald G Koch

Billy G Fuller

Richard Alan Windhausen

Richard D Miller

Michael A Smith

John Michael Nichols

Victor Medrano

Walter Patrick Christmas

Disclosed is a way of enhancing capabilities of an interface, such as a communications bus ( ), while retaining backwards compatibility of the interface. The bus has a plurality of signal lines ( ) including critical control signal lines. Legacy devices ( ) present a legacy interface to each other over the bus by communicating with each other via a legacy protocol ( ) over the bus. Critical control signals of the legacy protocol are conveyed by the critical control signal lines. New devices ( ) present an enhanced interface to each other over the same bus by communicating with each other via an enhanced protocol ( ) over the bus. Control signals of the enhanced protocol are conveyed by signal lines other than the critical control signal lines for the legacy protocol, so that the critical control signal lines remain idle or invalid for the legacy protocol. The new devices signal to each other an intent to use the enhanced protocol by sending a signal on a signal line ( ) that is not used by the legacy protocol. The new devices preferably can communicate on the bus via either protocol, and thus can communicate not only with each other but also with the legacy devices.

Arrangement for redefining an interface while maintaining backwards compatibility

An active-standby dual processor (,) performs only selective memory duplication and does so via hardware (,) and the operating system (,). A page table (,) stores a shadowing flag (,) for each memory page of the active memory (,) of the processor (,) that indicates whether or not the corresponding page is shadowed. When the operating system allocates (,) memory to a process&mdash;either statically at creation of the process or dynamically during execution of the process&mdash;it checks (,) whether the process program's data statement indicates shadowing or whether the MALLOC request includes a segment selector that indicates shadowing; if so, it sets (,) the allocated page's shadowing flag. When the active processor performs (,) a write of its memory, a page table controller (,) checks (,) if the written page's shadowing flag is set. If so, an interprocessor interface (,) is caused (,) to replicate the write on the standby processor's memory; if not, the write is not replicated.

Selective memory duplication arrangement

Growing community of inventors

Broomfield, CO, United States of America

Donald G Koch