Pre-validation of SoC via hardware and software co-simulation

Abstract. System-on-chips (SoCs) are complex entities consisting of multiple hardware and software components. This complexity presents challenges in their design, verification, and validation. Traditional verification processes often test hardware models in isolation until late in the development cycle. As a result, cooperation between hardware and software development is also limited, slowing down bug detection and fixing. This thesis aims to develop, implement, and evaluate a co-simulation-based pre-validation methodology to address these challenges. The approach allows for the early integration of hardware and software, serving as a natural intermediate step between traditional hardware model verification and full system validation. The co-simulation employs a QEMU CPU emulator linked to a register-transfer level (RTL) hardware model. This setup enables the execution of software components, such as device drivers, on the target instruction set architecture (ISA) alongside cycle-accurate RTL hardware models. The thesis focuses on two primary applications of co-simulation. Firstly, it allows software unit tests to be run in conjunction with hardware models, facilitating early communication between device drivers, low-level software, and hardware components. Secondly, it offers an environment for using software in functional hardware verification. A significant advantage of this approach is the early detection of integration errors. Software unit tests can be executed at the IP block level with actual hardware models, a task previously only possible with costly system-level prototypes. This enables earlier collaboration between software and hardware development teams and smoothens the transition to traditional system-level validation techniques.Järjestelmäpiirin esivalidointi laitteiston ja ohjelmiston yhteissimulaatiolla. Tiivistelmä. Järjestelmäpiirit (SoC) ovat monimutkaisia kokonaisuuksia, jotka koostuvat useista laitteisto- ja ohjelmistokomponenteista. Tämä monimutkaisuus asettaa haasteita niiden suunnittelulle, varmennukselle ja validoinnille. Perinteiset varmennusprosessit testaavat usein laitteistomalleja eristyksissä kehityssyklin loppuvaiheeseen saakka. Tämän myötä myös yhteistyö laitteisto- ja ohjelmistokehityksen välillä on vähäistä, mikä hidastaa virheiden tunnistamista ja korjausta. Tämän diplomityön tavoitteena on kehittää, toteuttaa ja arvioida laitteisto-ohjelmisto-yhteissimulointiin perustuva esivalidointimenetelmä näiden haasteiden ratkaisemiseksi. Menetelmä mahdollistaa laitteiston ja ohjelmiston varhaisen integroinnin, toimien luonnollisena välietappina perinteisen laitteistomallin varmennuksen ja koko järjestelmän validoinnin välillä. Yhteissimulointi käyttää QEMU suoritinemulaattoria, joka on yhdistetty rekisterinsiirtotason (RTL) laitteistomalliin. Tämä mahdollistaa ohjelmistokomponenttien, kuten laiteajureiden, suorittamisen kohdejärjestelmän käskysarja-arkkitehtuurilla (ISA) yhdessä kellosyklitarkkojen RTL laitteistomallien kanssa. Työ keskittyy kahteen yhteissimulaation pääsovellukseen. Ensinnäkin se mahdollistaa ohjelmiston yksikkötestien suorittamisen laitteistomallien kanssa, varmistaen kommunikaation laiteajurien, matalan tason ohjelmiston ja laitteistokomponenttien välillä. Toiseksi se tarjoaa ympäristön ohjelmiston käyttämiseen toiminnallisessa laitteiston varmennuksessa. Merkittävä etu tästä lähestymistavasta on integraatiovirheiden varhainen havaitseminen. Ohjelmiston yksikkötestejä voidaan suorittaa jo IP-lohkon tasolla oikeilla laitteistomalleilla, mikä on aiemmin ollut mahdollista vain kalliilla järjestelmätason prototyypeillä. Tämä mahdollistaa aikaisemman ohjelmisto- ja laitteistokehitystiimien välisen yhteistyön ja helpottaa siirtymistä perinteisiin järjestelmätason validointimenetelmiin

An empirical evaluation of High-Level Synthesis languages and tools for database acceleration

High Level Synthesis (HLS) languages and tools are emerging as the most promising technique to make FPGAs more accessible to software developers. Nevertheless, picking the most suitable HLS for a certain class of algorithms depends on requirements such as area and throughput, as well as on programmer experience. In this paper, we explore the different trade-offs present when using a representative set of HLS tools in the context of Database Management Systems (DBMS) acceleration. More specifically, we conduct an empirical analysis of four representative frameworks (Bluespec SystemVerilog, Altera OpenCL, LegUp and Chisel) that we utilize to accelerate commonly-used database algorithms such as sorting, the median operator, and hash joins. Through our implementation experience and empirical results for database acceleration, we conclude that the selection of the most suitable HLS depends on a set of orthogonal characteristics, which we highlight for each HLS framework.Peer ReviewedPostprint (author’s final draft

Build Testbenches for Verification in Shift Register ICs using SystemVerilog

A testbench is built to verify a functionality of a shift register IC (Integrated Circuit) from stuck-at-faults, stuck-at-1 as well as stuck-at-0. The testbench is supported by components, i.e., generator, interface, driver, monitor, scoreboard, environment, test, and testbench top. The IC consists of sequential logic circuits of D-type flip-flops. The faults may occur at interconnects between the circuits inside the IC. In order to examine the functionality from the faults, both the testbench and the IC are designed using SystemVerilog and simulated using Questasim simulator. Simulation results show the faults may be detected by the testbench. Moreover, the detected faults may be indicated by error statements in transcript results of the simulato

Build Testbenches for Verification in Shift Register ICs using SystemVerilog

A testbench is built to verify a functionality of a shift register IC (Integrated Circuit) from stuck-at-faults, stuck-at-1 as well as stuck-at-0. The testbench is supported by components, i.e., generator, interface, driver, monitor, scoreboard, environment, test, and testbench top. The IC consists of sequential logic circuits of D-type flip-flops. The faults may occur at interconnects between the circuits inside the IC. In order to examine the functionality from the faults, both the testbench and the IC are designed using SystemVerilog and simulated using Questasim simulator. Simulation results show the faults may be detected by the testbench. Moreover, the detected faults may be indicated by error statements in transcript results of the simulato

Formal Verification of a MESI-based Cache Implementation

Cache coherency is crucial to multi-core systems with a shared memory programming model. Coherency protocols have been formally verified at the architectural level with relative ease. However, several subtle issues creep into the hardware realization of cache in a multi-processor environment. The assumption, made in the abstract model, that state transitions are atomic, is invalid for the HDL implementation. Each transition is composed of many concurrent multi-core operations. As a result, even with a blocking bus, several transient states come into existence. Most modern processors optimize communication with a split-transaction bus, this results in further transient states and race conditions. Therefore, the design and verification of cache coherency is increasingly complex and challenging. Simulation techniques are insufficient to ensure memory consistency and the absence of deadlock, livelock, and starvation. At best, it is tediously complex and time consuming to reach confidence in functionality with simulation. Formal methods are ideally suited to identify the numerous race conditions and subtle failures. In this study, we perform formal property verification on the RTL of a multi-core level-1 cache design based on snooping MESI protocol. We demonstrate full-proof verification of the coherence module in JasperGold using complexity reduction techniques through parameterization. We verify that the assumptions needed to constrain inputs of the stand-alone cache coherence module are satisfied as valid assertions in the instantiation environment. We compare results obtained from formal property verification against a state-of-the-art UVM environment. We highlight the benefits of a synergistic collaboration between simulation and formal techniques. We present formal analysis as a generic toolkit with numerous usage models in the digital design process

Rapid high-level behavioral modeling of soc communication interfaces

Abstract. The increasing complexity of hardware and software systems increases the amount of labour and resources required to model them. Especially in system-on-chips (SoC), the complexity of modeling is evident. Electronic system-level (ESL) modeling using the benefits of transaction level modeling (TLM) reduces the required resources and speeds up the modeling time. This thesis examines approximately timed modeling in the context of behavioral modeling with abstract processing elements and abstract arbitration procedures. This thesis describes the basic principles of SoC:s and TLM, and then a problem of modeling a SoC communication interface for a company is investigated, and a TLM solution to the modeling problem is explored.Järjestelmäpiirien tiedonsiirtoyhteyksien nopea korkean tason käytösmallinnus. Tiivistelmä. Laitteistojen ja systeemien kasvava kompleksisuus lisää niiden mallinnukseen vaadittua työmäärää ja resursseja. Erityisesti järjestelmäpiireissä (SoC) mallinnuksen monimutkaistuminen näkyy. Elektronisen järjestelmätason (ESL) mallinnus käyttämällä tapahtumatason mallinnuksen (TLM) hyötyjä vähentää vaadittuja resursseja ja nopeuttaa mallinnukseen kuluvaa aikaa. Tässä opinnäytetyössä tarkastellaan likimääräisesti ajastettua mallinnusta käytösmallinnuksen kontekstissa abstrakteilla prosessointi elementeillä ja abstrakteilla sovittelu proseduureilla. Tässä työssä kuvataan myös järjestelmäpiirin ja TLM:n perusperiaatteet, jonka jälkeen tutkitaan erään yrityksen SoC:in tiedonsiirtoväylän mallinnuksen ongelmaa, ja tutkitaan TLM ratkaisua mallinnusongelmalle

Analyzing UVM reuse

Abstract. This thesis investigates Universal Verification Methodology’s (UVM) reuse possibilities. Initally, the object-oriented features of the UVM’s programming language SystemVerilog (SV), are introduced. Those features are one enabling factor in UVM reuse. The work also provides a brief overview to the development history of UVM and presents its properties. The structure of a conventional UVM testbench is also demonstrated. Finally, the features that make the UVM testbench more reusable are briefly introduced. In the practical part of the study, a UVM testbench is made for Nordic Semiconductor’s Introproject. The testbench was created with extensive comments so that beginners would get the most out of it. The methods that make the testbench reusable are also applied to the testbench. At the end of the practical part, the reuse possibilities of the testbench were tested by changing the Design Under Test (DUT). Modifications were made to the testbench in order to match the new features of the DUT.UVM uudelleenkäytön analysointi. Tiivistelmä. Tämä diplomityö tutkii Universaalin varmennusmenetelmän (UVM) uudelleenkäyttömahdollisuuksia. Aluksi UVM:n ohjelmointikielen, SystemVerilogin olio-ohjelmointipohjaisia ominaisuuksia käydään läpi. Nämä ominaisuudet ovat yksi mahdollistava tekijä UVM uudelleenkäytössä. Työssä tehdään lisäksi lyhyt katsaus UVM:n kehityshistoriaan ja esitellään myös sen ominaisuudet sekä tavanomaisen UVM-testipenkin rakenne. Lopuksi esitellään lyhyesti ominaisuuksia, jolla saa tehtyä UVM testipenkistä paremmin uudelleenkäytettävän. Työn käytännön osuudessa tehdään UVM-testipenkki Nordic Semiconductorin Introprojektiin. Testipenkki tehtiin laajasti kommentoimalla, jotta aloitteleva testipenkin tekijä saa siitä mahdollisimman paljon irti. Testipenkin tekemisessä käytettiin myös menetelmiä, joita esiteltiin aiemmassa teoriakappaleessa. Käytännön osuuden lopuksi testattiin testipenkin uudelleenkäyttöä muuttamalla testissä olevaa komponenttia. Testipenkkiin tehtiin muutokset, jolla se saatiin taas vastaamaan komponentin tarpeita

A Typing Discipline for Hardware Interfaces

Modern Systems-on-a-Chip (SoC) are constructed by composition of IP (Intellectual Property) Cores with the communication between these IP Cores being governed by well described interaction protocols. However, there is a disconnect between the machine readable specification of these protocols and the verification of their implementation in known hardware description languages. Although tools can be written to address such separation of concerns, the tooling is often hand written and used to check hardware designs a posteriori. We have developed a dependent type-system and proof-of-concept modelling language to reason about the physical structure of hardware interfaces using user provided descriptions. Our type-system provides correct-by-construction guarantees that the interfaces on an IP Core will be well-typed if they adhere to a specified standard

SystemVerilog Verification of Wishbone-Compliant Serial Peripheral Interface

Synchronous serial interfaces provide economical on-board communication between the processor, digital to analog and analog to digital converters, memory, and other building blocks on the chip. A number of Integrated Circuit (IC) manufacturers develop and produce components that are compatible with serial interfaces. The common serial interfaces include Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I2C), Universal Asynchronous Receiver Transmitter (UART), and Universal Serial Bus (USB). SPI is widely used and advantageous over other serial interfaces due to its features of simplicity, low cost, clock synchronous, and non-interrupting high-speed data transfer rate. SPI is the core controller of the design. An open source hardware computer bus Wishbone is selected as the host controller enabling parallel data exchange for faster communication. Both the hardware buses employ a master-slave configuration which makes the bus-interfacing easier. This research presents a verification environment using SystemVerilog for the SPI Master device. An existing design from Open Cores is re-used, described as per latest specifications in Verilog at the Register Transfer Level (RTL) and is in conformity with the design-reuse methodology. This paper provides an understanding of the verification, layered test benches, Object-Oriented Technology (OOT), SystemVerilog, SPI features, SPI advantages, disadvantages, and applications, SPI data transmission and transfer formats, SPI registers, SPI sub-system and Wishbone-SPI architecture, and the test bench development methodology. The focus is to understand how OOT and SystemVerilog improve productivity and functional coverage in a verification environment by the use of different constructs, constrained-random techniques, coverage, and assertions. A test bench was developed to verify the SPI master core. Testbench components include a random transaction generator, a Wishbone driver, an SPI master as the design under test, a receiver as the SPI slave, a monitor with tasks to monitor the host and the core, test cases, and a scoreboard to record metrics, assertions and store expected and actual data