RISC-V System IP

Overview

Key Features

• IOMMU
• IOMMU performs the corollary set of functions for device-based transactions as the CPU’s MMU functionality. This allows connected devices to be virtualized and operate within a unified virtual memory space with CPUs, while protecting the system from invalid device transactions.
• APLIC
• APLIC (Advanced Platform Level Interrupt Controller) can be used in systems that need to support wired interrupt signals. The APLIC controller converts between wired interrupts and their corresponding MSI memory mapped transactions sent within a RISC-V AIA interrupt architecture.
• CPX
• CPX (Cluster Proxy) enables Ventana compute chiplets to be seamlessly interfaced to a companion Hub SoC through a lightweight D2D transport of AMBA protocols. The CPX block integrates within the Hub SoC and bridges between the D2D PHY transport and the “proxy” CPU cluster interface connections within the Hub. The interface profile is detailed on the Ventana CPU product pages since it is unique to each product.

Benefits

• Interrupts
• RISC-V AIA (Advanced Interrupt Architecture) builds upon PCIe MSI (Message-Signaling Interrupts) to reduce the complexity of the interrupt implementation. Using memory mapped transactions removes the need for specialized interrupt protocols and sideband interrupt signaling networks. Ventana CPUs include the AIA IMSIG (Incoming Message- Signaled Interrupt Controller) function within the CPU cluster to process interrupts within each CPU core. The APLIC IP can be used if there are wired interrupts that need to be converted to MSI transactions.
• Debug & Trace
• RISC-V debug & trace utilizes a memory mapped architecture to remove the need for specialized protocols and sideband trace buses. CPU traces are sent to main memory with a timestamp using a unified system timebase (mtime) established at startup. CPU and system traces can then be read out from memory over any high-speed IO interface and combined using the timestamps to stitch together the system context.
• Memory Protection & Translation
• Ventana utilizes RISC-V architecture features that allows protection at the source of a transaction, compared to a destination approach as found in some common legacy architectures. Source side allows a richer and more fine grain set of protection constructs compared to a destination approach. The ePMP (enhanced Physical Memory Protection) functionality is implemented within Ventana’s CPU for CPU- based transitions, while the IOMMU protects against device-based transactions.

Technical Specifications