Arm Limited

University of Michigan

Jason Andrew Blome

Daryl Wayne Bradley

Krisztian Flautner

Scott Mahlke

A data processing system includes a register file having a plurality of registers storing respective register data values and an associated register value cache having a plurality of storage locations storing corresponding cache data values. There are fewer cache data values than registers. When a register is to be read, both the register data value and, if present, a cache data value from a corresponding storage location within the register value cache are read and compared by a comparator. This generates a match signal which indicates if the data values do not match that one of the data values is in error. The match signal stalls the processing and a CRC code initially stored with the cache data value and recalculated based upon the read cache data value are compared to determine whether or not the cache data value has changed since it was stored. If the cache data value has not changed, then it is correct and is output instead of the register data value. Alternatively, if the cache data value has changed, then the register data value is output.

Error detecting and correcting mechanism for a register file

A method of selecting where error detection circuits should be placed within an integrated circuit uses simulation of a reference and test design with errors injected into the test design and then fan out analysis performed upon those injected errors to identify error propagation characteristics. Thus, registers at which propagated errors are highly likely to manifest themselves or which protect key architectural state, or which protect state not otherwise protected can be identified and so an efficient deployment of error detection mechanisms achieved. Within an integrated circuit output signals from inactive circuit elements may be subject to isolation gating in dependence upon a detected current state of the integrated circuit. Thus, inactive circuit elements in which soft errors occur have inappropriate output signals gated from reaching the rest of the integrated circuit and thus reducing erroneous operation.

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Brooklyn, NY, United States of America

Jason Andrew Blome