[P4] Fw: [P4-design] Meeting minutes (Re: 4/10 draft agenda)

[LAKI Sandor]

________________________________
Feladó: P4-design <p4-design-bounces at lists.p4.org>, meghatalmazó: Calin Cascaval <cascaval at barefootnetworks.com>
Elküldve: 2017. április 10. 23:52:32
Címzett: Nate Foster
Másolatot kap: p4-design at lists.p4.org
Tárgy: [P4-design] Meeting minutes (Re: 4/10 draft agenda)


Language compatibility

What do we say at the workshop about backward compatibility

 - multiple implementations put more pressure on keeping stable releases more stable

 - hard to make promises that we’re not breaking compatibility

 - make an effort to keep compatibility w/o actually promising

- do we limit the scope to P4_14/16?

- do we know what changes are coming that potentially break compatibility?

    - composability and modularity

    - control plane

- is there a threshold for changes?

PR 158 - Add table of allowed member types in headers, structs, and tuples

  *   structs and tuples should behave the same – compiler non-conformant. tuples behave as listed, structs do not
  *   nesting? target restrictions on total size, etc.
  *   varbit? only one allowed in a header. Computed as the difference between total size and the rest of the fields
  *   error vs. match_kind in structs? match_kind is pretty much always used only as a type for table matches, and thus there is no need to store in variables.

AI:

  *   Andy to update with rationale
  *   update the table with header_union when approved (part of header_union PR)

Issue 150 - Global instances

  *   impact on resource allocation and sharing
  *   instantiations whether inline in a package decl or at top level should be the same
  *   instantiations should be done by either the program or the architecture. Should we restrict at one? Answers
  *   these tables/controls are not dead code, since the control plane can access them
  *   compiler should be careful to distinguish between control- and data-plane inlining. Control-plane inlining should behave as the control was not inlined.
  *   architecture dependent

AI: add a note of clarification to the spec

Issue 138 - Require unambiguous names

  *   multiple aliases and what order they apply?
     *   annotations are applied in program order, the last one remains exposed and all others become hidden
     *   need clarification
  *   Chris: proposes replacing rename with alias (and globalrename with globalalias)

AI: Cole to introduce in the spec

Issue 151 - Action calls from parsers

  *   we should add functions to parsers rather than hijacking actions which are part of the match-action abstraction (which parsers are not)

AI: add lambdas to the next version of the language

PR 127, Issue 124 - adds specification for table entries

AI: PR approval

--
Thanks, Calin

On Apr 10, 2017, at 12:20, Nate Foster <jnfoster at cs.cornell.edu<mailto:jnfoster at cs.cornell.edu>> wrote:

Here's a final agenda for today (with two additions from @jafingerhut and bumping header unions).

-N

* Status and Roadmap [5 minutes]

* Stability / Backwards Compatibility [10 minutes]

* P4 Types [10 minutes]
https://github.com/p4lang/p4-spec/pull/158

* Calling Actions from Parsers [10 minutes]
https://github.com/p4lang/p4-spec/issues/151

* Global Instances (Continued) [15 minutes]
https://github.com/p4lang/p4-spec/issues/150

* Control-Plane Names (Continued) [15 minutes]
https://github.com/p4lang/p4-spec/issues/138

* Table entries (Continued) [15 minutes]
https://github.com/p4lang/p4-spec/pull/127

* Other business [10 minutes]

On Sun, Apr 9, 2017 at 4:38 PM, Nate Foster <jnfoster at cs.cornell.edu<mailto:jnfoster at cs.cornell.edu>> wrote:
We meet again tomorrow from 1:30pm-3:00pm PT in Gates 260. We have a lot to discuss so I plan to start the meeting right at 1:30pm.

A draft agenda is below. Please let me know if you have anything you'd like to add to it. I'll circulate a final version tomorrow morning.

Draft Agenda:

* Status and Roadmap [5 minutes]

* Stability / Backwards Compatibility [15 minutes]

* Global Instances (Continued) [15 minutes]
https://github.com/p4lang/p4-spec/issues/150

* Control-Plane Names (Continued) [15 minutes]
https://github.com/p4lang/p4-spec/issues/138

* Header Unions (Continued) [15 minutes]

* Table entries (Continued) [15 minutes]
https://github.com/p4lang/p4-spec/pull/127

* Other business [10 minutes]

Call-in details:
* By computer: https://cornell.zoom.us/j/959432658
* By phone: +1 646 558 8656<tel:(646)%20558-8656> (US Toll) or +1 408 638 0968<tel:(408)%20638-0968> (US Toll). The Meeting ID is 959 432 658. International numbers are available at https://cornell.zoom.us/zoomconference?m=p414IDyY2yeauZygZLycHH0Vnc0wYEFg

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