PSL – Property Specification Language - OCP-IP

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PSL – Property Specification Language - OCP-IP

OCP PSL Package

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compliance with the License Terms."

1 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Content

ABV – Assertion-Based Verification

PSLProperty Specification Language

Motivation, Requirements & Content

Verification Flow

Installation & Integration

Known Problems and Limitations

Present & Future

Conclusions

2 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


ABV – Assertion-Based Verification

• The purpose is to convert functional features of a specification into explicit

hardware properties

• An assertion can be considered as an implementation of a property

• Several languages are available for implementation (e.g. PSL, SystemVerilog,

the e language, OpenVera, …)

• Assertions describe the behaviour of logic over time

• Assertions can be compiled and simulated as HDL descriptions

• Fully automatic verification method

• Increased visibility & simplified debugging

• The target is to improve both verification quality and efficiency!

3 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


ABV – Assertion-Based Verification

ALU ALU ALU

Test Bench

OCP

Register IF

Register IF

ALU ALU ALU

It is very difficult to backpropagate

bugs of internal

components!

Bugs of an interconnection

might lead to a complete

verification nightmare!

ALU ALU ALU

FSM

Assertions trigger

immediately and bring

bugs closer to their source!

4 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


PSLProperty Specification Language

• Hardware property (not verification) language!

• Utilized to implement assertions (not test benches)!

• The purpose is to complement the traditional methodologies

• Consistent, simple, and powerful language

• Declarative and structural syntax

• Very low learning threshold

• Four (4) different layers enable sustainable verification environments

• VHDL and Verilog flavors are provided

• Widely accepted standard from Accellera and IEEE

5 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


PSLProperty Specification Language

Boolean expressions i.e. a state of the DUV

property EXAMPLE is

never {a = ‘1’ and b = ‘1’};

Sequential expressions i.e. a sequence of states of the DUV

property EXAMPLE is

always {a = ‘0’ and b = ‘0’} |-> -- Precondition

{c = ‘0’ and d = ‘0’; -- Consequence

c = ‘1’ and d = ‘1’ [*2];

c = ‘0’ and d = ‘0’};

Both legal and illegal states or sequences of states can be determined!

6 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


PSLProperty Specification Language

“No ‘X’ or ‘Z’ on the master addr (MAddr) during the request phase”

property OCPPSL_MADDR_ISUNKNOWN is

never {MCmd /= OCP_IDLE and isunknown(MAddr)};

“The master address (MAddr) must remain stable during the request phase”

property OCPPSL_MADDR_STABLE is

always {MCmd /= OCP_IDLE} |->

{{SCmdAccept = ‘1’} |

{[*1];SCmdAccept = ‘0’ and stable(MAddr) [*];

SCmdAccept = ‘1’ and stable(MAddr)}}!

abort(MReset_n = RESET_ACTIVE);

7 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Motivation

• Since the number of intellectual property (IP) cores tends to increase, it has

become vital to verify interconnections

• VHDL or Verilog monitors are not cost-effective

• Verification languages (e.g. the e language and OpenVera) have been available,

but no widely accepted standards

• Tool dependent monitors are out of the question

• Ad-hoc methods have been utilized

• Verification quality has been found more or less inadequate.

• Sustainability has been found insufficient

• There is a clear demand for new kind of verification packages!

8 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Requirements

• Verifies the compatibility of the interconnection with the OCP 2.1

• Implementation based on open standards

• Compatible with the existing design and verification flow

• Can be configured according to the DUV

• Can be installed with minimal efforts without access to the source

• No previous knowledge is required

• Only a VHDL simulator is required

• Cost-effective in terms of maintenance and support

• Completely reusable

9 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Content

• 242 assertions divided to six (6) groups

• Basic signals 55

• Simple extensions 24

• Burst extensions 109

• Tag extensions 15

• Thread extensions 16

• Sideband signals 23

• 92 coverage points divided to three (3) groups

• Basic signals 19

• Simple extensions 9

• Burst extensions 64

10 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Verification Flow

Design

RTL

Test cases

YES

NO

Violations?

Simulate

RTL

NO

Coverage

YES

READY

Complete?

11 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Simulation Performance

• Exhaustive testing in a verification environment

• 6,340 independent requests

• 75 burst sequences containing 19,020 requests

• The CPU time when assertions disabled 132.83s

• The CPU time when assertions enabled 143.42s

• The performance penalty equals to 8.0%

• Very moderate, because the worst-case scenario was applied

• Note that results might vary between different simulators

12 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Installation

• The package consists of templates and must be modified according to the DUV

• The user must …

• set the parameters of the interconnection

• set the entity and architecture pair of verification units

• replace the names of the signals

• Remove assertions and sequences that contain unconnected signals

• Note! The following signals must be determined:

• Clk, MReset_n

• MCmd, MAddr, MData

• SCmdAccept, SResp, SData

• Otherwise auxiliary signals tied to default value must be implemented.

13 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Integration

OCP

Master

OCP

Slave

OCP

Slave

OCP 2.1 Interconnection

Violations?

Error msg

PSL

Assertions

14 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Known Problems and Limitations

• The support for the memory locks and reservation tags of the lazy

synchronization is missing

• The support of the tag and thread extensions is very limited

• The current release does not operate correctly if there are pending transactions

from multiple tags or threads

15 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M


Conclusions

• The package increases both verification quality and efficiency

• Straightforward installation and integration

• Fully automatic verification method

• Increased visibility & simplified debugging

• Very moderate performance penalty (max 8.0%)

16 © 2005 Nokia OCP PSL Package Introduction.ppt / 2006-05-12 / S.M

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