Minutes of the sv-sc sub-committee meeting, May 20, 2008

=================Attendance=============================

    20220 Day
    06817
    00000 Month
    55444
    00000 Year
    88888

--[----a]   Arturo Salz          - Synopsys
vv[a-aa-]   Abigail Morehouse    - Mentor
--[----a]   Bassam Tabbara       - Synopsys
--[----a]   Brad Pierce          - Synopsys
vv[a-aaa]   Cliff Cummings       - Sunburst Design
vv[aaaaa]   Dave Rich            - Mentor Graphics
vv[aa-aa]   Dmitry Korchemny     - Intel
vv[a-aa-]   Don Mills            -
vv[aaaaa]   Eduard Cerny         - Synopsys
tt[aaaaa]   Erik Seligman        - Intel (chair)
vv[aaaaa]   Francoise Martinolle - Cadence
vv[aaaaa]   Gordon Vreugdenhil   - Mentor Graphics
vv[aaaa-]   Jin Yang             - Intel
vv[aaaaa]   John Havlicek        - Freescale
--[----a]   Jonathan Bromley     - Doulas
--[--a-a]   Karen Pieper         - Accellera
vv[aaaaa]   Lisa Piper           - Cadence
vv[aaaaa]   Manisha Kulshrestha  - Mentor Graphics
vv[aaaaa]   Mark Hartoog         - Synopsys
vv[aaaaa]   Mehdi Mohtashemi     - Synopsys
vv[aaaaa]   Mirek Forczek        - Aldec
vv[aaaaa]   Neil Korpusik        - Sun Microsystems
--[---a-]   Ray Ryan             - Mentor
--[---aa]   Shalom Bresticker    - Intel
vv[aaaaa]   Steven Sharp         - Cadence
-v[--aaa]   Stu Sutherland       - Sutherland HDL
--[---aa]   Surrendra Dudani     - Synopsys
vv[aaaaa]   Tom Thatcher         - Sun Microsystems (co-chair)
v-[aa...]   Michael Burns        - Freescale
||
||---- Voting eligibility for current meeting
|------Voting eligibility for next meeting


The next meeting of the sv-sc will be held on Tuesday, May 20, 2008, 9am-11am (PDT).

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====================Agenda==============================
Agenda:

    1. Review the patent policy
    2. Approve the minutes from last week's F2F meeting, available at http://www.eda.org/twiki/bin/view.cgi/P1800/SvScMeetingMinutes200805F2F
    3. Action Item Review
           * Reminder: Review current proposals as partitioned at F2F
           * Current work on proposal revision: who is working on these? 
Need additional help?
    4. Technical topics
           * Checker variables revisited
                 o Reconsider F2F decision to drop continuous assigns, based on Dmitry's recent concerns
                 o Move assignments within checkers into Observed region?
           * Self-defined types: still OK, in light of examples emailed by Dmitry?
           * Checkers in procedural code: will always blocks in checkers be fully free-running? Do we still need $inferred_enable in some cases? 
(Erik to send some motivating examples)


====================Notes==============================

1.  Patent Policy:
     Move:  Gord  Consider the patent policy read
     Second:
     Approved unanimously
     Ref:  http://standards.ieee.org/board/pat/pat-slideset.ppt


2.  Approve minutes.
     Move:  Dmitry:  Approve the minutes from the last meeting.
     second:  Gordon
     Approved unanimously

3.  Action Item Review
     Reminder of action items from face-to-face meeting.
     Most people still in the process of reviewing Mantis items.

     Checker proposal:  Need people to start revising the checker proposal.
   Dmitry will take core checker proposal
   Other pieces:  Instantiation semantics, random var, all the rest.
   Mike Burns:  random var semantics.
   Gord:  believes random stability issues are his.
      Gord and Mike will work together on this.
   Part 1:  No volunteer:  Wait for a week on this one.


4.  Technical Topics

       * Checker variables revisited
     Dmitry   - Problems:  Don't see how continuous variable assignments
        in active region can work.
           - He wants to be able to assign ended and triggered to
        variables, and have these values trigger other assertions.
      - Worried about dumping of let.
      - His original proposal should work for Verilog.  Instead of
        his original ordering semantics, consider assignments like
        any other event.
     Steve   - This would introduce another small loop in observed region
     Steve   - May introduce loops in observed region.
           - May cause latching behavior
     Dmitry   - Need assignments to execute before property
     Gord   - This means another region
     Mike:   - Sounds like a lexical region where execution is in order.
     Gord   - If you allow writing in Observed, you re-open race conditions
     Mike   - Event structure has grown enormously. It's almost ridiculous


     Gord   - If you have parent & child sequence  If parent provides
             and reads output, there might be issues.  May not be cyclic,
        but there would be ordering requirements.
     Steven   - You would have to execute more than once.
     Dmitry   - What about scheduling non-blocking assignment updates in
        Re-NBA region?
     Gord   - This should be fine
     Steven   - What about symmetry:  Usually NBA processed in Active
        region update in NBA region, and NBA processed in Reactive
        region update in the Re-NBA region.


Self-defined types: Dmitry had some concerns.

     Mark   - Still need to discuss this.  Some people have concerns.
     Gord   - We had agreed that checker would behave same as sequences
            and properties, whatever the solution is
     Mark   - Why does let behave differently?
     Gord   - Let is a macro
     Mark   - Need to discuss this in future.
     Mike   - Exposure at Freescale at worst is minor, maybe nothing.

Checkers in procedural code inferred enable

     Erik   - What about always block that counts attempts, etc
     Gord   - You will probably just have to have another argument
             that's assigned.
     Tom      - What about race conditions?  Always block in checker could
             run before enclosing procedure runs
     Erik   - Maybe we don't need inferred enable


Question
     Dmitry   - Would it be reasonable to limit checkers to always_ff
     Gord   - Would be more comfortable limiting to plain always
           - Don't want to introduce synthesis semantics into checkers.

Meeting adjourned

-- ErikSeligman - 23 May 2008