Hierarchical Interconnect Access IDs for Mixed-Criticality Isolation
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Solution Overview
Problem
Existing transaction identifier/MMU/MPU based solutions in MCUs fail to provide the necessary granularity for access protection between applications and within applications with mixed criticality, leading to interference and inefficiencies in resource allocation.
Innovation Solution
A hierarchical access protection configuration system using two-part transaction identifiers, comprising an access protection main-ID (APMI) for application-level isolation and an access protection sub-ID (APSI) for task-level isolation, with a central initial software driver and application-specific hypervisors managing resource allocation and conflict detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional transaction identifier/MMU/MPU based solutions are used in MCUs, then basic access control is provided, but granular access protection between applications and within applications with mixed criticality is not achieved
Solution Approach 1:
The patent segments the transaction identifier into two distinct parts: APMI (Access Protection Main ID) for application-level isolation and APSI (Access Protection Sub ID) for task-level isolation within applications. This segmentation enables granular access control by allowing different access permissions to be assigned at both application and task levels, resolving the contradiction between providing fine-grained protection and maintaining manageable system complexity.
2Reliability
If application-level isolation is implemented without task-level isolation, then resource allocation between applications is protected, but interference within applications with mixed criticality occurs
Solution Approach 1:
The patent adds a second dimension to access control by introducing task-level isolation (APSI) alongside application-level isolation (APMI). This creates a hierarchical two-dimensional access control structure where APMI provides the first dimension of isolation between applications, and APSI provides the second dimension of isolation within applications. This dimensional expansion enables both application-level resource protection and task-level resource allocation efficiency to coexist.
3Reliability
If fine-grained access control is implemented, then interference between applications is reduced, but system complexity and configuration overhead increase
Solution Approach 1:
The patent merges application identification and task identification into a single unified transaction identifier structure that contains both APMI and APSI components. This merging approach allows the system to provide fine-grained access control through the combined identifier rather than requiring separate identifier mechanisms, thereby reducing overall system complexity while maintaining the benefits of granular protection.
Data Source
AI summary
Systems, methods, and circuitries are provided for controlling access the secondary modules in a controller based on a two part identifier. In one example, a controller includes one or more primary modules, one or more secondary modules, and an interconnect. Each primary module is configured to generate access requests with respect to the one or more secondary modules. The interconnect couples the one or more primary modules to the one or more secondary modules. The interconnect is configured to assign a transaction identifier to each access request. The transaction identifier is mapped to a type of read and/or write access in one or more secondary modules and includes a main component mapped to an application in execution by the primary module that generated the access request, and a sub component mapped to a sub-task of the application in execution by the primary module that generated the access request.