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Copyright © 2008 by Doulos. All rights reserved.
Scenario Generator (VMM)
Verification environment
Scenario generator
Downstream transactor
generator's output channel
atomic
scenario_set
burst[1]
[0]
RMW[2]
burst
items
select_scenario
select
copies of items](https://image.slidesharecdn.com/jonathanbromleydoulos-130422122710-phpapp02/85/The-Verification-Methodology-Landscape-21-320.jpg)
The Verification Methodology Landscape
- 1. 1 Copyright © 2008 by Doulos. All rights reserved. The Verification Methodology Landscape Jonathan Bromley, Doulos DVClub Bristol 22-April-2009
- 2. 2 Copyright © 2008 by Doulos. All rights reserved. The Verification Methodology Landscape CONTENTS The M-word Languages, methodologies, tools and standards The big players: OVM, VMM, eRM Interoperability and convergence Conclusions?
- 3. 3 Copyright © 2008 by Doulos. All rights reserved. TLM DUT Monitor Driver Verification Environment Stimulus generator Transactions Coverage collector Transaction recording Test controller Scoreboard / Checker
- 4. 4 Copyright © 2008 by Doulos. All rights reserved. Design Under Test Constrained Random Verification 11001001 01001010 00001001 01110110 01100110 01001001 01001110 000010 010011 000010 100100 001000 110010 000011 Constrained random stimulus Checker Did we see a bug? Functional Coverage Are we done?Header Payload Checksum Constraints Increase coverage
- 5. 5 Copyright © 2008 by Doulos. All rights reserved. The Verification Space Verification Acceleration + Emulation Formal Verification Simulation Equivalence Checking Property Checking Dynamic Formal Coverage Transaction Level Modelling Constrained Random Assertions Simulation Simulation Simulation Formal Simulation Formal Intelligent Testbench
- 6. 6 Copyright © 2008 by Doulos. All rights reserved. What Our Customers Want • Ease of deployment • Customizable environment • but it must do something useful straight out of the box • Simple, uniform interface to any verification IP block • Gentle learning curve for the whole team • Power • Complex testcases co-ordinated across the whole environment • Randomization • Sophisticated coverage analysis • Interoperability • Every customer we meet has legacy verification IP
- 7. 7 Copyright © 2008 by Doulos. All rights reserved. Methodology (or just a toolkit?) • Tame the language monster • e, SystemVerilog, C++ are big and complicated • Many ways to solve a problem • Wheel reinvention is a hazard • Toolkit • OOP encourages encapsulation of standard functionality in base classes • Ideal for component hierarchy, reporting, block-to-block communication, DUT connectivity • Methodology • Published methodology encourages interoperability and re-use • Promote best practice
- 8. 8 Copyright © 2008 by Doulos. All rights reserved. Mature Language Standards • IEEE 1076 VHDL • IEEE 1850™ PSL • IEEE 1364 Verilog • IEEE 1800™ SystemVerilog • IEEE 1647™ e • ISO/IEC 14882 C++ • IEEE 1666™ SystemC • Tcl/Tk, Perl List unchanged for 4 years... 8 FPGA, RTL, Europe, Mil-Aero ASIC, RTL, USA/RoW Hardware verification Virtual hardware prototypes for S/W dev Hardware verification Crude Caricature Modelling, verification Scripting
- 9. 9 Copyright © 2008 by Doulos. All rights reserved. New Standards Activity • Verilog and SystemVerilog unified • LRM this year, currently in ballot feedback • Major enhancements to assertions • Verification methodology • OVM 2.0, OVM-SC • VMM open-source • eRM3 - e / SV interoperability (Cadence) • OVM / VMM interoperability (Accellera) • SystemC TLM-2.0
- 10. 10 Copyright © 2008 by Doulos. All rights reserved. The Big Methodology Players www.ovmworld.org www.vmmcentral.org www.cadence.comeRM
- 11. 11 Copyright © 2008 by Doulos. All rights reserved. Environment Static View of Testbench DUT active agent Driver BFM Monitor BFM Sequ- encer passive agent Driver BFM Monitor BFM Sequ- encer checkerConfiguration simple ports (e) virtual interfaces (SV) eRM
- 12. 12 Copyright © 2008 by Doulos. All rights reserved. Static View of Testbench (VMM) DUT Generator ... test_env env = new; env.run(); ... Transactor Driver Self Check Monitor High level transactions Checker Monitor Functional Coverage Properties Checker Atomic transactions Constraints; directed tests
- 13. 13 Copyright © 2008 by Doulos. All rights reserved. OVM Key Features • Constrained random, coverage-driven verification • Separation of tests from verification environment • Configuration of verification environment • through a table • Verification IP reuse (canonical structure and guidelines) • TLM communication • Automation (where missing from SystemVerilog language) • Hierarchical sequential stimulus (sequences) • Standardized messaging
- 14. 14 Copyright © 2008 by Doulos. All rights reserved. eRM Key Features • Constrained random, coverage-driven verification • Separation of tests from verification environment • Configuration of verification environment • through AOP extension and pre-run constraints • Verification IP reuse (rigorously standardized rules) • Communication via ports • Automation (using e language's macro features) • Hierarchical sequential stimulus (sequences) • Standardized messaging
- 15. 15 Copyright © 2008 by Doulos. All rights reserved. VMM Key Features • Constrained random, coverage-driven verification • Configuration of verification environment • through configuration objects passed to verification components • Verification IP reuse (conventions) • Communication via channels, callbacks, notifications • Automation (scripts and macros) • Hierarchical sequential stimulus (scenarios) • Standardized messaging • Strongly influenced by RVM (Synopsys Vera)
- 16. 16 Copyright © 2008 by Doulos. All rights reserved. Structure of an OVM Component class my_driver extends ovm_driver #(my_transaction); // ovm_seq_item_pull_port #(...) seq_item_port; my_dut_if_wrapper m_dut_if; function new(string name, ovm_component parent); super.new(name, parent); endfunction: new function void build; super.build(); endfunction: build virtual task run; forever begin ... end endtask: run endclass: my_driver TLM port (inherited) Connection to DUT Constructor Build phase callback Run phase callback Base class
- 17. 17 Copyright © 2008 by Doulos. All rights reserved. Phase Methods (OVM) build connect end_of_elaboration start_of_simulation run extract check report Call factory Make TLM connections After connections hardened Post-processing Task (executed concurrently) Get ready to run Similar phase arrangements in VMM, eRM
- 18. 18 Copyright © 2008 by Doulos. All rights reserved. Reconfigurable Environment (OVM) DUT Reusable verification environment Scoreboard Virtual sequencer Monitor Existing verification component Existing verification component Sequencer DriverMonitor Config Test Test set_config_* Customize environments set_inst_override_* set_type_override_* Customize types By type or instance path
- 19. 19 Copyright © 2008 by Doulos. All rights reserved. Layered Sequential Stimulus DUTDriverDrive transactions into DUT tx1 tx2 tx3 Constrained random sequence of transactions seq1 seq2seq2 Virtual or layered sequences tx1 Tests enumerate possible top-level sequences Randomized transactions are not enough
- 20. 20 Copyright © 2008 by Doulos. All rights reserved. ovm_env ovm_agent Virtual Sequences ovm_sequencer ovm_driver ovm_sequencer Component hierarchy Stimulus hierarchy (co-ordinated interfaces) DUT dut_if ovm_agent ovm_sequencer ovm_driver dut_if ovm_sequence ovm_sequence_item ovm_sequence
- 21. 21 Copyright © 2008 by Doulos. All rights reserved. Scenario Generator (VMM) Verification environment Scenario generator Downstream transactor generator's output channel atomic scenario_set burst[1] [0] RMW[2] burst items select_scenario select copies of items
- 22. 22 Copyright © 2008 by Doulos. All rights reserved. Now and Next • VMM: rapidly growing collection of "applications" • register abstraction layer, hierarchy, ... • OVM/VMM interoperability toolkits/standards • OVM/eRM mixed-language tools • OVM-SC • Increasing availability of verification IP
- 23. 23 Copyright © 2008 by Doulos. All rights reserved. Conclusion • Interesting times • standards don't always keep up with user needs • Challenges for users choosing a new approach: • tools? • methodology? • decisions are not yet completely decoupled • Training is important: • VMM, OVM, eRM are not difficult ... • ... but jump-starting your efforts pays dividends
- 24. 24 Copyright © 2008 by Doulos. All rights reserved.