Michael I Will

US Patent:

56490887, Jul 15, 1997

Filed:

Aug 12, 1996

Appl. No.:

8/695543

Inventors:

Richard Stephen Hauck - St. Charles IL
David Arthur Welch - Bristol IL
Michael James Will - Naperville IL

Assignee:

Lucent Technologies Inc. - Murray Hill NJ

International Classification:

G07F 1100

US Classification:

395181

Abstract:

A fault recovery system and method that deterministically reconstructs the instruction stream of a multiple execution stage ("pipelined") processor. A log ("queue") is provided for each critical data item to record the instructions, operations and effects as processing proceeds. Also, rather than merely freezing the execution of a specific stage upon occurrence of a fault, all stages are stopped so that each stage does not overwrite log information that is needed to reconstruct the instruction flow immediately preceding the invocation of any fault recovery operation. The fault recovery operation may then serially reconstruct the instruction flow, advantageously starting with the instruction where the fault occurred, working to reconstruct from that instruction to the last instruction that was executing before the fault recovery operation began.