P4 match constraints

[Jiarong Xing]

Hi there,

I am using P4-16 to program a Netronome Agilio CX NIC. I found that if I use two ternary match keys in a P4 table, I cannot install more than 4 rules for that table. If I try installing more, I will get this error: pif_dcfl.c:318 table xxx contains too many fields.

Is this caused by any constraints of Netronome? If so, are there other constraints that I should be aware of when writing a P4 program?

Thank you! 

[Maksymilian Czudziak]

Yes, there are many constrains to P4 programming on Agilio CX that you should be aware of.
For example, both P4 version doesn't support checking (in control block) if the table was hit.

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Best regards,

Maksymilian Czudziak
Junior Software Engineer | CodiLime

m:
e: maksymilia...@codilime.com

codilime.com

[Jiarong Xing]

Hi Maksymilian,  thank you for your timely reply! Interesting to know this.  Do you know any docs that I can look at to learn more about these limitations? 

[Maksymilian Czudziak]

The only doc that I'm aware of, which mentions this topic is  “Netronome Network Flow Processor 6xxx: Development Tools User's Guide” Appendix F.

But I haven't found, there, most of the limitations that held me back during development, for example the one that I mentioned in the message above.

--
Best regards,

Maksymilian Czudziak
Junior Software Engineer | CodiLime

m:
e: maksymilia...@codilime.com

codilime.com

[Jiarong Xing]

Got it! Thank you for your help!!

[Deepak Choudhary]

Hi Jiarong,

The NFP Development Tools User's Guide (also called the devtools document) details many design limits (like the maximum number of table entries, number of headers, etc) in Appendix F.

Regards,

Deepak.

[Jiarong Xing]

Great to know that. Thank you, Deepak!!!