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rocket-chip/rocket/README.md
2014-09-17 11:23:25 -07:00

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Rocket Core

Rocket is a 6-stage single-issue in-order pipeline that executes the 64-bit scalar RISC-V ISA. Rocket implements an MMU that supports page-based virtual memory and is able to boot modern operating systems such as Linux. Rocket also has an optional IEEE 754-2008-compliant FPU, which implements both single- and double-precision floating-point operations, including fused multiply-add.

This repository is not intended to be a self-running repository. To instantiate a Rocket core, please use the Rocket chip generator found in the rocket-chip git repository.

The following table compares a 32-bit ARM Cortex-A5 core to a 64-bit RISC-V Rocket core built in the same TSMC process (40GPLUS). Fourth column is the ratio of RISC-V Rocket to ARM Cortex-A5. Both use single-instruction-issue, in-order pipelines, yet the RISC-V core is faster, smaller, and uses less power.

ISA/Implementation ARM Cortex-A5 RISC-V Rocket R/A
ISA Register Width 32 bits 64 bits 2
Frequency >1 GHz >1 GHz 1
Dhrystone Performance 1.57 DMIPS/MHz 1.72 DMIPS/MHz 1.1
Area excluding caches 0.27 mm2 0.14 mm2 0.5
Area with 16KB caches 0.53 mm2 0.39 mm2 0.7
Area Efficiency 2.96 DMIPS/MHz/mm2 4.41 DMIPS/MHz/mm2 1.5
Dynamic Power <0.08 mW/MHz 0.034 mW/MHz >= 0.4