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P4 Behavioural Simulation

Makefile

The execution of P4 behavioural simulations is driven by the Makefile in the p4/sim/ directory.

This Makefile includes the variable assignments that specify how to run a p4 behavioural simulation, as well as the name of the p4 file and list of testcases that should be included in a full simulation run.

Each testcase is captured in a separate subdirectory, which contains the input and output files for the specified test. The testcase subdirectories follow the naming pattern of test-<NAME>.

Prior to running a simulation, the user should update the Makefile with the following variable assignments (all other variable assignments can remain unchanged):

 P4_SOURCE = <pathname of p4 source file>
 P4BM_DIRS = <testcase subdirectory list>

The Makefile includes execution targets to run (or clean) a single testcase simulation, or simulation of the full testcase suite.

To simulate a single testcase, execute make with the P4BM_DIR= argument set to the testcase subdirectory of interest. For example:

 > make P4BM_DIR=test-fwd-p0

Or to simulate all test cases:

 > make sim-all

Note: the sim-all target is the default target when make is called without arguments.

To clean all simulation output products from the p4 directory, type:

 > make clean

Testcase Input Files

The input stimulus file set for each testcase includes four files:

  1. cli_commands.txt - Command script to set table entries and initiate input stimulus. Commands and syntax follow the Xilinx p4bm-vitisnet-cli.

  2. packets_in.user - Input packet stream user data. Each byte sequence terminated by a semicolon (;) represents a packet. Packets are captured in sequence. The '%' character is used to start comments.

    packets_in.pcap - PCAP file containing the input packet stream. Alternative format to packets_in.user (optional).

  3. packets_in.meta - Input packet metadata. Each line corresponds to a packet in the input PCAP file (in sequence). The syntax of the metadata is described in the Xilinx VitisnetP4 documentation. Note: Each metadata record must be terminated by a semicolon (;).

  4. smartnic_extern.cpp - C++ behavioural model for any user extern functions. Located in the user_externs/ subdirectory (co-located with the test-<NAME> subdirectories).

For more details, see chapter 3 of Vitis Networking P4 User Guide, UG1308 (v2023.1) May 16, 2023.

Testcase Output Files

  1. packets_out.user - Output packet stream user data. Same syntax as input packet stream user data.

    packets_out.pcap - PCAP file containing the output packet stream, if packets_in format was packets_in.pcap.

  2. packets_out.meta - Output packet metadata. Each line corresponds to a packet in the output PCAP file (in sequence). Same syntax as input packet metadata.

Note: An expected/ directory is optionally included to capture the expected output results of a testcase. This expected output can be used for automated regression testing.

Testcases: p4_with_extern

test-fwd-p0 - The p4_with_extern design includes a single example testcase called test-fwd-p0. This testcase programs a small number of table entries that forward the specified packet flows to destination port 0. The input stimulus includes a single packet on each flow to validate that all packets are forwarded to port 0. All other packets are forwarded to the egress_port specified by the input meta data.