.. BSD LICENSE Copyright(c) 2010-2014 Intel Corporation. All rights reserved. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of Intel Corporation nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Hello World Sample Application ============================== The Hello World sample application is an example of the simplest DPDK application that can be written. The application simply prints an "helloworld" message on every enabled lcore. Compiling the Application ------------------------- #. Go to the example directory: .. code-block:: console export RTE_SDK=/path/to/rte_sdk cd ${RTE_SDK}/examples/helloworld #. Set the target (a default target is used if not specified). For example: .. code-block:: console export RTE_TARGET=x86_64-native-linuxapp-gcc See the *DPDK Getting Started* Guide for possible RTE_TARGET values. #. Build the application: .. code-block:: console make Running the Application ----------------------- To run the example in a linuxapp environment: .. code-block:: console $ ./build/helloworld -c f -n 4 Refer to *DPDK Getting Started Guide* for general information on running applications and the Environment Abstraction Layer (EAL) options. Explanation ----------- The following sections provide some explanation of code. EAL Initialization ~~~~~~~~~~~~~~~~~~ The first task is to initialize the Environment Abstraction Layer (EAL). This is done in the main() function using the following code: .. code-block:: c int main(int argc, char **argv) { ret = rte_eal_init(argc, argv); if (ret < 0) rte_panic("Cannot init EAL\n"); This call finishes the initialization process that was started before main() is called (in case of a Linuxapp environment). The argc and argv arguments are provided to the rte_eal_init() function. The value returned is the number of parsed arguments. Starting Application Unit Lcores ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Once the EAL is initialized, the application is ready to launch a function on an lcore. In this example, lcore_hello() is called on every available lcore. The following is the definition of the function: .. code-block:: c static int lcore_hello( attribute ((unused)) void *arg) { unsigned lcore_id; lcore_id = rte_lcore_id(); printf("hello from core %u\n", lcore_id); return 0; } The code that launches the function on each lcore is as follows: .. code-block:: c /* call lcore_hello() on every slave lcore */ RTE_LCORE_FOREACH_SLAVE(lcore_id) { rte_eal_remote_launch(lcore_hello, NULL, lcore_id); } /* call it on master lcore too */ lcore_hello(NULL); The following code is equivalent and simpler: .. code-block:: c rte_eal_mp_remote_launch(lcore_hello, NULL, CALL_MASTER); Refer to the *DPDK API Reference* for detailed information on the rte_eal_mp_remote_launch() function.