Bluespec SystemVerilog Research Articles

Сравнение инструментов высокоуровневого синтеза и конструирования цифровой аппаратуры

Application-specific systems with FPGA accelerators are often designed using high-level synthesis or hardware construction tools. Nowadays, there are many frameworks available, both open-source and commercial. In this work, we attempt to fairly compare several existing solutions (languages and tools), including Verilog (our baseline), Chisel, Bluespec SystemVerilog (Bluespec Compiler), DSLX (XLS), MaxJ (MaxCompiler), and C (Bambu and Vivado HLS). Our analysis has been carried out using a representative example of 8×8 inverse discrete cosine transform (IDCT), a widely used algorithm engaged in, among others, JPEG and MPEG decoders. The metrics under consideration include: (a) the degree of automation (how much less code is required compared to Verilog), (b) the controllability (possibility to achieve given design characteristics, namely a given ratio of the performance and area), and (c) the flexibility (ease of design modification to achieve certain characteristics). Rather than focusing on computational kernels only, we have developed AXI-Stream wrappers for the synthesized implementations, which allows adequately evaluating characteristics of the designs when they are used as parts of real computer systems. Our study shows clear examples of what impact specific optimizations (tool settings and source code modifications) have on the overall system performance and area. It emphasizes how important is to be able to control the balance between the communication interface utilization and the computational kernel performance and delivers clear guidelines for the next generation tools for designing FPGA accelerator based systems.

Fast Protection-Domain Crossing in the CHERI Capability-System Architecture

Capability Hardware Enhanced RISC Instructions (CHERI) supplement the conventional memory management unit (MMU) with instruction-set architecture (ISA) extensions that implement a capability system model in the address space. CHERI can also underpin a hardware-software object-capability model for scalable application compartmentalization that can mitigate broader classes of attack. This article describes ISA additions to CHERI that support fast protection-domain switching, not only in terms of low cycle count, but also efficient memory sharing with mutual distrust. The authors propose ISA support for sealed capabilities, hardware-assisted checking during protection-domain switching, a lightweight capability flow-control model, and fast register clearing, while retaining the flexibility of a software-defined protection-domain transition model. They validate this approach through a full-system experimental design, including ISA extensions, a field-programmable gate array prototype (implemented in Bluespec SystemVerilog), and a software stack including an OS (based on FreeBSD), compiler (based on LLVM), software compartmentalization model, and open-source applications.

Blueshell

The rapid increase in FPGA logic capacity has enabled the prototyping of multiprocessor Network-on-Chip (NoC) architectures. However, the design space exploration of these complex architectures is highly time consuming with traditional methodologies for FPGA design. Our paper addresses the challenges of multiprocessor network design with the Blueshell framework for generating multiprocessor networks on chip (NoC) and a coupled Java software stack, Network-Chi. With Blueshell hardware is mconstructed from high-level components including processors and routers using concise Bluespec System Verilog. The Network-Chi software framework is also presented to enable programming the on-chip processors in a familiar Java style and without exposing the low-level systems programming to the application designer. We demonstrate that Blueshell systems with as many as 20 processors can be implemented on a modestly sized FPGA. Performance figures for a selection of distributed applications are also provided.

A New Design Methodology for Composing Complex Digital Systems

Continuous growth in the use of multimedia applications on portable devices makes the mobile computer systemshave an increasing complexity. The functionalities of the used SOC chips and silicon intelligent properties in theseportable devices are become complicated and hard to design. Traditional digital circuit designs adopt register transferlevel with timing control methodologies, which focus on the datapath composition, timing control of registers, and thefunctions of combinational circuits. However, the huge amount of control and synchronous signals of the abovecomponents are difficult to design and debug. The timing costs of design and verification are increased dramatically.This paper proposed a new design methodology of digital system, called data-oriented methodology, to deal with theabove problems, by using Bluespec SystemVerilog HDL and the corresponding tools. Instead of conventional timingcontrolmechanism, the data-oriented methodology adopts simple handshaking protocol, blocking transferring, andexplicitly register/FIFO declaration for communicating between adjacent modules. The designs of FDCT/IDCT andpipelined MIPS-like CPU are adopted to compare the design costs of conventional timing-control and data-orientedmethodologies. The chip performance and FPGA proven of these two designs are discussed

A Novel Data-Oriented Methodology for Designing Complex SOC System with Bluespec SystemVerilog

The continuously growing of semiconductor technology makes the novel SOC system complicated and hard to design. Conventional timing-control methodology focuses on the synchronizing the registers in a digital system. However, the central control of huge amount of synchronous signals and states is difficult to maintain and design, the debugging and verification period is extended accordingly. This paper proposed a novel deign methodology, called data-oriented methodology, to overcome the above challenges, by using Bluespec SystemVerilog and the corresponding tools. The simple handshaking mechanism and blocking mechanism are adopted to make sure the correctness of adjacent blocks, the complex centralized control unit can be reduced accordingly. Two examples, FDCT/IDCT and pipelined MIPS CPU, are provided to demonstrate two types of typical digital designs.

Automatic generation of hardware/software interfaces

Enabling new applications for mobile devices often requires the use of specialized hardware to reduce power consumption. Because of time-to-market pressure, current design methodologies for embedded applications require an early partitioning of the design, allowing the hardware and software to be developed simultaneously, each adhering to a rigid interface contract. This approach is problematic for two reasons: (1) a detailed hardware-software interface is difficult to specify until one is deep into the design process, and (2) it prevents the later migration of functionality across the interface motivated by efficiency concerns or the addition of features. We address this problem using the Bluespec Codesign Language~(BCL) which permits the designer to specify the hardware-software partition in the source code, allowing the compiler to synthesize efficient software and hardware along with transactors for communication between the partitions. The movement of functionality across the hardware-software boundary is accomplished by simply specifying a new partitioning, and since the compiler automatically generates the desired interface specifications, it eliminates yet another error-prone design task. In this paper we present BCL, an extension of a commercially available hardware design language (Bluespec SystemVerilog), a new software compiling scheme, and preliminary results generated using our compiler for various hardware-software decompositions of an Ogg Vorbis audio decoder, and a ray-tracing application.

Automatic generation of hardware/software interfaces

Enabling new applications for mobile devices often requires the use of specialized hardware to reduce power consumption. Because of time-to-market pressure, current design methodologies for embedded applications require an early partitioning of the design, allowing the hardware and software to be developed simultaneously, each adhering to a rigid interface contract. This approach is problematic for two reasons: (1) a detailed hardware-software interface is difficult to specify until one is deep into the design process, and (2) it prevents the later migration of functionality across the interface motivated by efficiency concerns or the addition of features. We address this problem using the Bluespec Codesign Language~(BCL) which permits the designer to specify the hardware-software partition in the source code, allowing the compiler to synthesize efficient software and hardware along with transactors for communication between the partitions. The movement of functionality across the hardware-software boundary is accomplished by simply specifying a new partitioning, and since the compiler automatically generates the desired interface specifications, it eliminates yet another error-prone design task. In this paper we present BCL, an extension of a commercially available hardware design language (Bluespec SystemVerilog), a new software compiling scheme, and preliminary results generated using our compiler for various hardware-software decompositions of an Ogg Vorbis audio decoder, and a ray-tracing application.

A monadic approach to automated reasoning for Bluespec SystemVerilog

We embed a non-trivial subset of Bluespec SystemVerilog (BSV) in the higher order logic of the PVS theorem prover. Owing to the clean semantics of BSV, application of monadic techniques leads to a ...

High-Level Design and Validation of the BlueSPARC Multithreaded Processor

This paper presents our experiences in using high-level methods to design and validate a 16-way multithreaded microprocessor called BlueSPARC. BlueSPARC is an in-order, high-throughput processor supporting complex features such as privileged-mode operations, memory management, and a nonblocking cache subsystem. Using a high-level design language called Bluespec System Verilog (BSV), our final implementation achieves comparable synthesis quality to a similar commercial microprocessor developed using conventional register transfer level flows, and is capable of running unmodified commercial applications while hosted on a Xilinx XCV2P70 field-programmable gate array (FPGA) at 90 MHz. To validate our implementation, an FPGA-accelerated approach was developed to efficiently check the correct execution of real, nondeterministic multithreaded programs running on the BlueSPARC processor. Together, the high-level language features of BSV along with our validation approach enabled us to achieve a working FPGA-based implementation in less than one man-year.

What is Bluespec?

Bluespec refers to a language and associated tools which are being used for all aspects of hardware system design . specification, synthesis, modeling, and verification. The language, BSV (Bluespec SystemVerilog), is based on a new model of computation for hardware, where all behavior is described as a set of rewrite rules, or Guarded Atomic Actions. Unlike the process/thread model of Verilog, VHDL and SystemC, or the sequential model of C/C++, all behavior of a BSV program can be understood in terms of atomic rule firings. This computational model has a long pedigree in formal specification and verification systems (e.g., Dijkstra's Guarded Commands, UNITY, TLA+, and EventB), and BSV makes it available for hardware design.

What is Bluespec?

Bluespec refers to a language and associated tools which are being used for all aspects of hardware system design . specification, synthesis, modeling, and verification. The language, BSV (Bluespec SystemVerilog), is based on a new model of computation for hardware, where all behavior is described as a set of rewrite rules, or Guarded Atomic Actions. Unlike the process/thread model of Verilog, VHDL and SystemC, or the sequential model of C/C++, all behavior of a BSV program can be understood in terms of atomic rule firings. This computational model has a long pedigree in formal specification and verification systems (e.g., Dijkstra's Guarded Commands, UNITY, TLA+, and EventB), and BSV makes it available for hardware design.