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rocket-chip/rocket
Andrew Waterman 354cb2d5ec Don't stall I$ response when resolving a branch misprediction
This avoids a fetch bubble.

Not clear if this is the best way to do it.  Perhaps this change should
instead be made to Frontend (i.e., ignore resp.ready when req.valid is
high), but that might exacerbate a critical path.
2016-05-24 15:05:41 -07:00
..
src/main/scala Don't stall I$ response when resolving a branch misprediction 2016-05-24 15:05:41 -07:00
.gitignore add .gitignore 2014-08-18 19:27:50 -07:00
build.sbt Add ability to generate libraryDependency on cde. 2015-10-22 11:37:20 -07:00
LICENSE add LICENSE 2014-09-12 15:36:42 -07:00
README.md update README 2014-09-17 11:23:25 -07:00

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