Differences in EDA Tool Support for Designing RISC-V and ARM Processors

At the fifth RISC-V China Summit last week, many EDA companies announced their support for RISC-V. When designing a chip, what are the differences in EDA tool support between designing a RISC-V processor and an ARM processor? Through research, Lao Zhang summarized that there are significant ecological differences, toolchain availability, IP compatibility, and software support between designing a RISC-V processor and an ARM processor. Below is a comparative analysis from multiple dimensions:

1. Differences in Licensing Models and Development Starting Points

Item	RISC-V	ARM
Licensing Method	Open-source Instruction Set Architecture (ISA), no license required for design	Commercial licensing, ARM IP license required for development
Development Threshold	Can customize instruction set and microarchitecture from scratch	Developed based on ARM Cortex IP, ISA usually cannot be changed
EDA Tool Adaptation	More freedom, but requires custom adaptation	Toolchain has many ready-made templates, mature adaptation

➡️Result: Designing a RISC-V processor requires starting from architecture definition, ISA configuration, and simulation verification, with higher demands for EDA customization and underlying modeling capabilities. A metaphor is that designing an ARM processor is like preparing a banquet with pre-made dishes delivered to the kitchen; designing RISC-V is more like starting from planting vegetables, but with the freedom to adjust flavors.

2. Comparison of EDA Toolchain Adaptation

1. Frontend Design (RTL Design, Simulation, Functional Verification)

Aspect	RISC-V	ARM
RTL Templates	Optional open-source cores (e.g., Rocket, CV32E40P), but mostly need customization	ARM IP comes with complete RTL and verification packages
Simulation Platform Support	EDA vendors need to specifically adapt to different RISC-V cores (large ISA variations)	General support, tools come with ARM simulation model interfaces
Functional Verification (e.g., UVS, VCS)	Support is increasingly enhanced, but models need to be provided or adapted by developers	ARM IP comes with a mature verification environment and Testbench

➡️Conclusion: ARM has a high degree of IP commercialization, and verification processes are standardized; RISC-V design requires developers to have more EDA adaptation capabilities.

2. Backend Implementation (Synthesis, Timing, DFT, Physical Implementation)

Tool Support Items	RISC-V	ARM
Logic Synthesis	Good compatibility, manual optimization needed for paths caused by polymorphic ISA	Official IP optimized, synthesis guidelines clear
DFT Automation	DFT platform needs to adapt to custom core structures	ARM cores have mature DFT structures, EDA tools optimized
Layout and Routing	Core structures vary, Place & Route optimization is complex	ARM has standard levels and Macro structures, optimization paths are clear

➡️Conclusion: ARM processor backend design paths are clear, and EDA tools have a lot of “pre-configured” options; RISC-V has high freedom but relies more on custom EDA toolchain capabilities.

3. Formal Verification & Functional Equivalence Checking

ARM: Major manufacturers provide Golden Reference Models, EDA tools (e.g., Formality) can directly verify.
RISC-V: Requires self-built or open-source ISA Models (e.g., Spike), increasing complexity of verification processes.

3. Differences in Software-Hardware Co-design and System Simulation Support

Module	RISC-V	ARM
System Simulation (e.g., VCS, Synopsys Platform Architect)	Lacks a unified model, users need to build their own software stack	ARM collaborates deeply with EDA vendors (e.g., AMBA bus/IP co-simulation)
Software Ecosystem Toolchain	LLVM/GCC support but not unified, debugging interfaces need adaptation	Commercial IDEs like KEIL, DS-5 are mature, kernel debugging is smooth
Virtual Platforms (e.g., Synopsys Virtualizer)	RISC-V models need to be integrated by users	ARM virtual cores have standard configurations and API interfaces

4. Differences in IP Interfaces and System Integration Support

Content	RISC-V	ARM
Standard Interface Protocols (e.g., AXI/AHB)	Diverse, some RISC-V cores do not natively support	Strict specifications, high integration depth in toolchains
IP Reuse Platforms (e.g., DesignWare)	High adaptation costs, some IP does not support RISC-V	In the ARM ecosystem, the threshold for IP usage is lower, and interface standards are unified
Third-party EDA Toolchain Support	Strengthened in recent years (e.g., Siemens, Cadence have adapted)	Default support for mainstream ARM IP, mature full process

5. Differences in Actual Industry Development Experience

Feature	RISC-V	ARM
Development Cycle	High flexibility but long cycle	High integration of tools + IP, cycle is more controllable
Innovation Freedom	Can add custom instruction sets and innovative microarchitectures	Limited by ARM protocols, small modification space
Tool Difficulty/Experience Requirement	Highly dependent on the capabilities of the chip team	Can leverage a wealth of ARM ecosystem resources and vendor support

6. Conclusion: EDA Level Comparison of RISC-V vs ARM

Comparison Dimension	RISC-V	ARM
Toolchain Maturity	Medium-low, requires continuous adaptation	High, deeply coupled
Verification Tool Support	Weaker than ARM, needs model construction	Complete
Design Flexibility	High, can customize instructions and core structures	Limited by ARM IP framework
Development Difficulty	High, strong autonomy	Relatively low
Commercial Closed-loop Support	Forming	Mature system

📌 Final Remarks: RISC-V design offers more freedom at the EDA tool level but also presents more challenges; the ARM design ecosystem is more closed but has more mature EDA tools. From this summit, it can be seen that EDA vendors are gradually enhancing their support for RISC-V (e.g., Cadence launched a RISC-V verification platform, Synopsys supports RISC-V simulation models), but current RISC-V design teams still need to possess stronger toolchain adaptation and software-hardware co-design capabilities.

These are some summaries; feel free to add any omissions!