Access Controller Circuit Size Reduction via Intermediate Identifier Mapping
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Solution Overview
Problem
In recent data processing apparatuses, the increasing number of peripheral resources leads to a large volume of permission configuration information, resulting in an increase in the size of the circuit that stores this information, which is inefficient.
Innovation Solution
The data processing apparatus employs an access controller that selects permission configuration information and an identifier table using processor selection information, determines an intermediate identifier for access requests, and uses this information to determine accessibility, thereby reducing the circuit size by limiting permission configurations to intermediate identifiers rather than access request identifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of peripheral resource entries is increased, then the system can support more processors and operation units, but the volume of permission configuration information and the size of the circuit storing this information increases
Solution Approach 1:
The permission configuration information is segmented into two parts: identifier table information (mapping operation unit identifiers to intermediate identifiers) and permission information (storing access rights for intermediate identifiers). This segmentation allows the system to support multiple operation units while keeping the permission information compact by using intermediate identifiers instead of storing separate permission data for each operation unit-processor pair.
Solution Approach 2:
An intermediate identifier is introduced as a mediator between operation unit identifiers and processor identifiers. The identifier table maps operation unit identifiers to intermediate identifiers, which then serve as keys to retrieve permission information. This intermediary layer reduces the overall circuit size by consolidating permission data through the intermediate identifier mechanism.
2Reliability
If permission configuration information is stored for each access request identifier, then precise access control is achieved, but the number of registers required increases significantly
Solution Approach 1:
The system changes the parameter used for permission lookup from the full access request identifier to an intermediate identifier. By transforming the identifier through the identifier table, the system maintains precise access control (reliability) while reducing the number of registers needed, since permission information is stored keyed by the shorter intermediate identifier rather than the complete access request identifier.
Data Source
AI summary
According to one embodiment, a data processing apparatus includes an access controller configured to control access by a CPU to a processor. The access controller selects permission configuration information and an identifier table to be used for the access control using processor selection information output from the CPU, determines as intermediate identifier MID that corresponds to an access request identifier SPID output from the CPU using the selected identifier table, and determines accessibility of the CPU to the processor using the selected permission configuration information and the determined intermediate identifier MID.