Config facts & Dangerous Precedent - was: potential command line option

From: Clifford E. Cummings (cliffc@sunburst-design.com)
Date: Sun Apr 24 2005 - 20:50:12 PDT

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    Hi, All -

    Another new subject line to separate out the issues.

    Config facts:

    · I wrote the Verilog-2001 BNF - it was far better than the
    Verilog-1995 BNF but it still had errors.
    · In 1996 I helped champion the effort to put configurations on the
    Verilog top-5
    · Tom Fitzpatrick and I championed the Verilog-1995 the config
    proposal for Verilog-2001
    · config, endconfig and library were intended to be Verilog keywords
    (see Draft-4 Annex B include in my email of 4/21/2005)
    · The config proposal was intended to make it possible to instantiate
    two modules with the same name but from different source files without
    modifying the source files, which was required by the non-standard `uselib
    directive . It also was intended to eliminate the need for the
    -v -y +libext+.v+ and many -f command line switches, not to substitute
    other switches in their place.
    · At least one tool has implemented configs according to the
    implementation that I envisioned when I helped propose configurations.

    BNF facts:
    · I wrote the Verilog-2001 BNF and it had many errors.
    · We have not required vendors to implement error-BNF syntax once we
    have identified the errors.
    · There have been many places in the standard where the informative
    examples helped to identify errors in the normative BNF. When we find
    discrepancies, we as a committee discuss the differences and decide what
    needs to be changed. In some cases, it is the BNF that needs to be changed.
    · Although we should make every effort to make the BNF perfect, the
    BNF is not perfect and the BNF-alone should not constitute the final word
    regarding correct Verilog syntax

    Config future
    · We should clarify whatever we think is the right thing to do with
    configs. This is a group decision.

    Dangerous Precedent
    · I guess the follow-on question is, do we really want to set a
    precedent that might allow a vendor to implement a SystemVerilog feature
    and then have other companies come back a few years later and request a
    significant change to the feature to make it easier to implement on another
    tool? Because, as you all have seen, I have a long memory for this type of
    stuff
    ;-) ;-)

    Regards - Cliff

    ----------------------------------------------------
    Cliff Cummings - Sunburst Design, Inc.
    14314 SW Allen Blvd., PMB 501, Beaverton, OR 97005
    Phone: 503-641-8446 / FAX: 503-641-8486
    cliffc@sunburst-design.com / www.sunburst-design.com
    Expert Verilog, SystemVerilog, Synthesis and Verification Training

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