Building and Running a Target
Each P4 program (called a 'target') is set up in a directory under targets/. Inside the target directory is a Makefile with the instructions on how to build the behavioral model for that P4 program.
cd targets/project_name
make bm
This should result in an executable in the same directory called "behavioral_model"
大概意思：P4程序 也叫‘Target’，是在 target/.目录下建立的；在这个target目录下，是一个Makefile文件，和一个介绍如何为P4程序build一个行为模型的文件。
做了个测试：
cd /home/wasdns/p4factory/targets/switch
make bm
Integration with Mininet 和 Mininet 一起运行
Integration with Mininet provides a way to instantiate a network of nodes each running a data plane described in P4.
We provide a Mininet integration for one of our existing targets: simple_router
To run it, do the following:
cd p4factory/targets/simple_router/
make bm
./run_demo.bash
To install some table entries, run the following (in a different terminal):
./run_add_demo_entries.bash
跑的时候出现了错误：
好吧，解决方法说依赖关系重叠，我只好重新安装了下p4factory，解决问题。
You can then type commands in the Mininet CLI:
mininet> h1 ping h2
建立了一个简单拓扑，但是h1和h2并没有ping通。这让我很奇怪，h1 ping s1 还有 h2 ping s1 都没有问题。
Creating a New Target
To add a new target, cd to targets/ and run:
p4factory/tools/newtarget.py project_name
where project_name is the name of the P4 program (without the .p4 extension). This will create a new directory in targets/ called project_name/, set it up to build the behavioral model, and create a template for the P4 program there named project_name.p4. Then, edit that file or copy your P4 program to that file and make in that directory.
这个就是生成P4程序的命令了；可以用这个命令创建一个没有.p4后缀的P4程序，在targets/目录下，在该目录下创建一个文件
.p4，用vim编辑它或者直接把P4代码拷贝过去，make即可。
P4 Dependency Graph Generator
这个命令是用来辅助生成P4程序的依赖图表的：The relationships between tables of more complex P4 program can be difficult to comprehend. The p4-graphs utility parses through the the P4 program and generates a dependency graph using graphviz. The dependency graph can be generated with the following command:
p4-graphs <p4 code>
The resulting files can be viewed using xdot or with a PNG viewer.
Towards a better behavioral model: bmv2
新的P4行为模型，如果你在一个P4程序里面看到bmv2目录的话，那么就意味着它支持bmv2.
We have released a new version of the behavioral model, written in C++. Some targets already support this new model -in addition to the original version, p4c-behavioral. If you see a target with a bmv2 directory, it means the new model is supported and you can try it out!
The new model splits the switch logic and the auto-generated PD API (drivers) into 2 different processes.
跑支持bmv2的程序，你可以这样做：
For example, the l2_switch target supports bmv2. To run the code, you can do the following:
cd targets/l2_switch/bmv2/
make bm
./run_bm.sh # to start the data plane
然后新打开Terminal，执行下面这句，打开API：
sudo ./drivers # in a second terminal, to start the PD APIs (RPC server)
打开第三个Terminal，跑这些例子：
sudo python run_tests.py --test-dir tests/ptf-tests/
2016/9/27