mirror of https://github.com/F-Stack/f-stack.git
78 lines
2.6 KiB
ReStructuredText
78 lines
2.6 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2010-2014 Intel Corporation.
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Hello World Sample Application
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==============================
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The Hello World sample application is an example of the simplest DPDK application that can be written.
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The application simply prints an "helloworld" message on every enabled lcore.
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Compiling the Application
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-------------------------
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To compile the sample application see :doc:`compiling`.
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The application is located in the ``helloworld`` sub-directory.
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Running the Application
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-----------------------
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To run the example in a linux environment:
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.. code-block:: console
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$ ./<build_dir>/examples/dpdk-helloworld -l 0-3 -n 4
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Refer to *DPDK Getting Started Guide* for general information on running applications
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and the Environment Abstraction Layer (EAL) options.
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Explanation
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-----------
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The following sections provide some explanation of code.
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EAL Initialization
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~~~~~~~~~~~~~~~~~~
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The first task is to initialize the Environment Abstraction Layer (EAL).
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This is done in the main() function using the following code:
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.. literalinclude:: ../../../examples/helloworld/main.c
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:language: c
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:start-after: Initialization of Environment Abstraction Layer (EAL). 8<
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:end-before: >8 End of initialization of Environment Abstraction Layer
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This call finishes the initialization process that was started before main() is called (in case of a Linux environment).
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The argc and argv arguments are provided to the rte_eal_init() function.
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The value returned is the number of parsed arguments.
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Starting Application Unit Lcores
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Once the EAL is initialized, the application is ready to launch a function on an lcore.
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In this example, lcore_hello() is called on every available lcore.
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The following is the definition of the function:
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.. literalinclude:: ../../../examples/helloworld/main.c
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:language: c
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:start-after: Launch a function on lcore. 8<
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:end-before: >8 End of launching function on lcore.
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The code that launches the function on each lcore is as follows:
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.. literalinclude:: ../../../examples/helloworld/main.c
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:language: c
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:start-after: Launches the function on each lcore. 8<
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:end-before: >8 End of launching the function on each lcore.
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:dedent: 1
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The following code is equivalent and simpler:
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.. literalinclude:: ../../../examples/helloworld/main.c
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:language: c
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:start-after: Simpler equivalent. 8<
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:end-before: >8 End of simpler equivalent.
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:dedent: 2
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Refer to the *DPDK API Reference* for detailed information on the rte_eal_mp_remote_launch() function.
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