[P4-dev] clone_egress_pkt_to_egress number of parameters

Antonin Bas antonin at barefootnetworks.com
Wed Aug 3 17:27:55 EDT 2016

Hi Thomas,

Optional arguments for primitive actions (and primitive action overloading)
are not supported by bmv2, so it was decided to make the field_list
parameter required. I believe the next version of the language (scheduled
to be release before the end of the year) will not include support for
optional parameters, which is why I have not deemed necessary to add the
complexity of optional parameters to bmv2.
I guess we could change p4c-bmv2 to generate an empty field list argument
when clone_* is called without a second argument. But usually P4
programmers want to at least carry some metadata information and include
the standard metadata to the field list.



On Wed, Aug 3, 2016 at 2:13 PM, Thomas Edwards <Thomas.Edwards at fox.com>

> I noticed that although OK with p4c-bmv2, and listed as optional according
> to the P4 Language Specification v1.0.2, the bmv2 simple_switch target
> appears to be unhappy with clone_egress_pkt_to_egress if is does not have
> the field_list parameter, and reports:
> "Invalid number of parameters for primitive action
> clone_egress_pkt_to_egress: expected 2 but for 1"
> -Thomas
> --
> Thomas Edwards
> VP Engineering & Development
> FOX Networks Engineering and Operations
> thomas.edwards at fox.com
> Phone: +1.310.369.6696
> 10201 West Pico Blvd.
> Los Angeles, CA 90035
> _______________________________________________
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