Software Mediation Unit for Memory Protection Without MMU
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Solution Overview
Problem
Conventional information processing devices require dedicated hardware like Memory Management Units (MMUs) for memory protection, increasing costs and complexity.
Innovation Solution
An information processing device with a mediation unit that uses software to manage memory access by writing and reading identification information for tasks, detecting memory abnormalities without dedicated hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated hardware such as MMU is used for memory protection, then memory protection reliability is improved, but device cost and complexity increase
Solution Approach 1:
The patent replaces the mechanical/dedicated hardware system (MMU) with a software-based mediation unit that runs on the existing CPU. This software unit performs memory access mediation by comparing task IDs with allocation information, achieving memory protection functionality without requiring specialized hardware components.
Solution Approach 2:
The mediation unit is designed to handle multiple tasks and memory allocation scenarios through a single unified software component. It can mediate memory access for any task by retrieving allocation information from the memory management data structure, making the system universally applicable to different memory protection scenarios without needing task-specific hardware.
2Reliability
If dedicated hardware such as MMU is used for memory protection, then memory protection reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the mechanical/dedicated hardware system (MMU) with a software-based mediation unit that runs on the existing CPU. This software unit performs memory access mediation by comparing task IDs with allocation information, achieving memory protection functionality without requiring specialized hardware components.
Solution Approach 2:
The patent uses software (a mediation unit program) instead of expensive hardware to achieve memory protection. Software is significantly cheaper to produce and modify than hardware, allowing memory protection functionality to be added without increasing manufacturing costs.
3Device complexity
If software-mediated memory management is used, then device complexity is reduced, but processing speed may decrease
Solution Approach 1:
The patent pre-organizes memory allocation information in a structured data format in the memory management data structure before access occurs. This allows the mediation unit to quickly retrieve and compare allocation information with task IDs during memory access, minimizing processing overhead and speed penalty.
Solution Approach 2:
The mediation unit is designed to efficiently query the memory management data structure using the task ID as a key, allowing for rapid lookup and comparison. The system serves itself by using the existing CPU and memory infrastructure to handle the mediation, minimizing the need for additional processing resources.
Data Source
AI summary
An information processing device according to an embodiment includes a memory and a mediation unit. The memory includes memory use areas that are allocated to respective tasks, and an identification-information area that identifies the tasks. The mediation unit mediates writing and reading, by one of the tasks, into and from one of the memory use areas. When accepting a request of the writing and reading from the one task, the mediation unit writes one of the identification informations corresponding to the one task into the identification-information area, further reads information memorized in the identification-information area at a predetermined timing, and detects an abnormality in the memory on the basis of the read information.