Added P4 Behavioral Model

[snifbh]

This pull request contains:

• A general switch P4 behavioral model.
• Implementation of the SAI API over the P4 BM.
• unit test example for the sai api usage.
• Thirft sai server implementation and ptf tests.

currently only L2 (1D,1Q) flows are supported.

[kcudnik]

Almost 600 files in one commit ? can you split that into couple PR ? Are all files go to BM directory ?

[snifbh]

1. All files are in the BM directory.
2. this PR needs the P4 environment (~60% of the files), found under BM/p4-softswtich/. it is required to compile the BM.
3. this pull request can be splitted: the PTF, unittest, and sai_thrift_server (BM/sai_adapter/tests/ ~100 files) are done in another PR, but I think that the tests show usage examples and simplify the model understanding.

[kcudnik]

Does this needs to be in SAI repo ? is that developed for SAI ? or maybe this can be in other repo and jus be git submodule here? I believe nobody will be able to do review of this code in this form

[lguohan]

yes, this provides the official SAI compliant software switch.

[lguohan]

@snifbh, can you rename the root directory to bm? we are using non capital letters.

[YonatanPitz]

@lguohan done.

[lguohan]

did we modify any p4 switch behavior model? Is it possible to use submodule to link to a p4 switch behavior model here? The concern is that from time to time we probably want to upgrade to a new p4 switch behavior model.

I prefer to only have following in the SAI repo.

• our p4 program, P4-SAI.
• Implementation of the SAI API over the P4 BM.
• unit test example for the sai api usage.
• Thirft sai server implementation and ptf tests.

Then, we can have a submodule link to bmv2 software, so that we can compile our P4-SAI model.

This may be cleaner and more easy to understand our own contribution.

[snifbh]

@lguohan
I agree that using the behavioral model as submodule here is much cleaner.
But we have implementation issue:
Currently the behavioral model doesn't support external target (our P4-SAI MUST be in the behavioral-model/targets/ folder)
We might be able work around this, but it will be much less clean.
I'll try to open the external target feature with the P4 community, but for now, I suggest we keep it like this.

[lguohan]

we can do this using our own build script, for example, first copy our target to the behaviroal-model/targets/folder and then compile.

[snifbh]

@lguohan done.