A Soft-Error Mitigated Microprocessor With Software Controlled Error Reporting and Recovery

A MIPS 4Kc compliant embedded microprocessor design that incorporates architectural features for software controlled soft-error recovery is presented. The design leverages classical fault tolerance techniques, e.g., error detection and instruction restart, implemented at the micro-architectural level, and added instructions for error recovery. Soft-errors are detected as the instructions commit to architectural state. At this point, an exception is taken and software recovers the correct machine state and restarts execution. The software recovery allows full machine inspection to determine error root causes. Added instructions also facilitate silicon validation of the hardware and software recovery mechanisms. The design is implemented in a commercial low standby power 90-nm bulk CMOS process and the prototype operates at up to 336 MHz. Finally, proton broad beam irradiation results are presented. The processor demonstrates correct recovery, resuming program operation, from over 500 detected soft-errors, with no unrecoverable errors.