Static Hardware Partitioning on RISC-V -- Shortcomings, Limitations, and Prospects

Fuente: arXiv
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Autores principales: Ramsauer, Ralf, Huber, Stefan, Schwarz, Konrad, Kiszka, Jan, Mauerer, Wolfgang
Formato: Preprint
Publicado: 2022
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author Ramsauer, Ralf
Huber, Stefan
Schwarz, Konrad
Kiszka, Jan
Mauerer, Wolfgang
author_facet Ramsauer, Ralf
Huber, Stefan
Schwarz, Konrad
Kiszka, Jan
Mauerer, Wolfgang
contents On embedded processors that are increasingly equipped with multiple CPU cores, static hardware partitioning is an established means of consolidating and isolating workloads onto single chips. This architectural pattern is suitable for mixed-criticality workloads that need to satisfy both, real-time and safety requirements, given suitable hardware properties. In this work, we focus on exploiting contemporary virtualisation mechanisms to achieve freedom from interference respectively isolation between workloads. Possibilities to achieve temporal and spatial isolation-while maintaining real-time capabilities-include statically partitioning resources, avoiding the sharing of devices, and ascertaining zero interventions of superordinate control structures. This eliminates overhead due to hardware partitioning, but implies certain hardware capabilities that are not yet fully implemented in contemporary standard systems. To address such hardware limitations, the customisable and configurable RISC-V instruction set architecture offers the possibility of swift, unrestricted modifications. We present findings on the current RISC-V specification and its implementations that necessitate interventions of superordinate control structures. We identify numerous issues adverse to implementing our goal of achieving zero interventions respectively zero overhead: On the design level, and especially with regards to handling interrupts. Based on micro-benchmark measurements, we discuss the implications of our findings, and argue how they can provide a basis for future extensions and improvements of the RISC-V architecture.
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id arxiv_https___arxiv_org_abs_2208_02703
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Static Hardware Partitioning on RISC-V -- Shortcomings, Limitations, and Prospects
Ramsauer, Ralf
Huber, Stefan
Schwarz, Konrad
Kiszka, Jan
Mauerer, Wolfgang
Hardware Architecture
On embedded processors that are increasingly equipped with multiple CPU cores, static hardware partitioning is an established means of consolidating and isolating workloads onto single chips. This architectural pattern is suitable for mixed-criticality workloads that need to satisfy both, real-time and safety requirements, given suitable hardware properties. In this work, we focus on exploiting contemporary virtualisation mechanisms to achieve freedom from interference respectively isolation between workloads. Possibilities to achieve temporal and spatial isolation-while maintaining real-time capabilities-include statically partitioning resources, avoiding the sharing of devices, and ascertaining zero interventions of superordinate control structures. This eliminates overhead due to hardware partitioning, but implies certain hardware capabilities that are not yet fully implemented in contemporary standard systems. To address such hardware limitations, the customisable and configurable RISC-V instruction set architecture offers the possibility of swift, unrestricted modifications. We present findings on the current RISC-V specification and its implementations that necessitate interventions of superordinate control structures. We identify numerous issues adverse to implementing our goal of achieving zero interventions respectively zero overhead: On the design level, and especially with regards to handling interrupts. Based on micro-benchmark measurements, we discuss the implications of our findings, and argue how they can provide a basis for future extensions and improvements of the RISC-V architecture.
title Static Hardware Partitioning on RISC-V -- Shortcomings, Limitations, and Prospects
topic Hardware Architecture
url https://arxiv.org/abs/2208.02703