Safe Memory Data Block Access Using Check Value Verification
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Solution Overview
Problem
Existing functionally safe execution platforms, such as those used in automotive systems, face challenges with high energy consumption, large space requirements, and scalability issues due to lockstep concepts, particularly for high-performance cores and systems with large program code and data, limiting their applicability in autonomous driving applications.
Innovation Solution
A method that enables safe data access by assigning check values to data blocks, allowing operation in a safe mode without additional hardware, using conventional memory units and buses, and employing specific instruction categories to ensure data integrity and error detection, suitable for high-performance cores and large data systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lockstep concept with redundant processor core is used, then functional safety is improved, but energy consumption and space requirement increase significantly
Solution Approach 1:
The patent extracts the safety verification function from the hardware domain (redundant processor core) and relocates it to the software domain (check values and safe operating mode). Only the necessary safety-checking components are retained in hardware (memory unit storing check values), while the verification logic is implemented as software instructions, dramatically reducing hardware overhead and energy consumption.
Solution Approach 2:
Instead of copying the entire processor core (lockstep method), the patent copies only the essential safety-critical data and creates check values (hash values) as simplified representations. This lightweight copying approach provides safety verification without the full overhead of redundant core implementation.
2Reliability
If lockstep concept with redundant processor core is used, then functional safety is improved, but device complexity and space requirement increase
Solution Approach 1:
The patent extracts the safety verification function from the hardware domain (redundant processor core) and relocates it to the software domain (check values and safe operating mode). Only the necessary safety-checking components are retained in hardware (memory unit storing check values), while the verification logic is implemented as software instructions, dramatically reducing hardware overhead and energy consumption.
Solution Approach 2:
The processor core is designed to be universal and can operate in both normal mode (high performance) and safe operating mode (with check value verification). The same hardware resources are used for both safety-critical and non-safety-critical operations, eliminating the need for dedicated safety hardware and reducing overall device complexity.
3Reliability
If lockstep method is used for high-performance cores, then functional safety is maintained, but scalability and performance are limited
Solution Approach 1:
The patent introduces a dynamic operating mode mechanism that allows the system to switch between normal mode (optimized for high performance) and safe operating mode (with enhanced safety verification). This dynamic adaptation enables the system to achieve high performance when safety verification is not strictly required, while maintaining functional safety when needed, thus resolving the performance-safety tradeoff.
Solution Approach 2:
The patent changes the operational parameters of the processor by introducing a safe operating mode with specific instruction categories (first, second, third categories) that enable safety verification. By changing the operational state rather than the hardware architecture, the system can achieve functional safety without compromising the inherent performance of high-performance cores.
4Device complexity
If conventional memory units are used without additional hardware, then space and energy requirements are reduced, but data integrity verification capability is limited
Solution Approach 1:
The patent introduces check values (hash values) as intermediary elements that mediate between the data stored in conventional memory and the verification process. These check values serve as compact representations that enable integrity verification without requiring complex hardware. The check values act as a bridge that allows software-based verification of data stored in standard memory units.
Solution Approach 2:
The patent replaces mechanical/hardware-based verification systems (redundant processor cores, dedicated safety hardware) with software-based verification mechanisms. By substituting hardware mechanisms with software instructions that compute and verify check values, the system achieves data integrity verification using conventional memory units without additional hardware overhead.
Data Source
AI summary
A method for accessing a data block, stored in a memory unit of a computing unit, of a number of data blocks. The method includes: activating a safe operating mode of the computing unit; in the safe operating mode of the computing unit, accessing the data block; if the access is a read access, reading data from the data block and subsequently writing the data into the data block; if the access includes a write access, reading first data from the data block, removing the first data from a check value associated with the data block, writing second data into the data block, adding the second data to the check value associated with the data block; and checking the check value associated with the data block.