1.. BSD LICENSE 2 Copyright(c) 2010-2014 Intel Corporation. All rights reserved. 3 All rights reserved. 4 5 Redistribution and use in source and binary forms, with or without 6 modification, are permitted provided that the following conditions 7 are met: 8 9 * Redistributions of source code must retain the above copyright 10 notice, this list of conditions and the following disclaimer. 11 * Redistributions in binary form must reproduce the above copyright 12 notice, this list of conditions and the following disclaimer in 13 the documentation and/or other materials provided with the 14 distribution. 15 * Neither the name of Intel Corporation nor the names of its 16 contributors may be used to endorse or promote products derived 17 from this software without specific prior written permission. 18 19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31Hello World Sample Application 32============================== 33 34The Hello World sample application is an example of the simplest DPDK application that can be written. 35The application simply prints an "helloworld" message on every enabled lcore. 36 37Compiling the Application 38------------------------- 39 40To compile the sample application see :doc:`compiling`. 41 42The application is located in the ``helloworld`` sub-directory. 43 44Running the Application 45----------------------- 46 47To run the example in a linuxapp environment: 48 49.. code-block:: console 50 51 $ ./build/helloworld -l 0-3 -n 4 52 53Refer to *DPDK Getting Started Guide* for general information on running applications 54and the Environment Abstraction Layer (EAL) options. 55 56Explanation 57----------- 58 59The following sections provide some explanation of code. 60 61EAL Initialization 62~~~~~~~~~~~~~~~~~~ 63 64The first task is to initialize the Environment Abstraction Layer (EAL). 65This is done in the main() function using the following code: 66 67.. code-block:: c 68 69 int 70 71 main(int argc, char **argv) 72 73 { 74 ret = rte_eal_init(argc, argv); 75 if (ret < 0) 76 rte_panic("Cannot init EAL\n"); 77 78This call finishes the initialization process that was started before main() is called (in case of a Linuxapp environment). 79The argc and argv arguments are provided to the rte_eal_init() function. 80The value returned is the number of parsed arguments. 81 82Starting Application Unit Lcores 83~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 84 85Once the EAL is initialized, the application is ready to launch a function on an lcore. 86In this example, lcore_hello() is called on every available lcore. 87The following is the definition of the function: 88 89.. code-block:: c 90 91 static int 92 lcore_hello( attribute ((unused)) void *arg) 93 { 94 unsigned lcore_id; 95 96 lcore_id = rte_lcore_id(); 97 printf("hello from core %u\n", lcore_id); 98 return 0; 99 } 100 101The code that launches the function on each lcore is as follows: 102 103.. code-block:: c 104 105 /* call lcore_hello() on every slave lcore */ 106 107 RTE_LCORE_FOREACH_SLAVE(lcore_id) { 108 rte_eal_remote_launch(lcore_hello, NULL, lcore_id); 109 } 110 111 /* call it on master lcore too */ 112 113 lcore_hello(NULL); 114 115The following code is equivalent and simpler: 116 117.. code-block:: c 118 119 rte_eal_mp_remote_launch(lcore_hello, NULL, CALL_MASTER); 120 121Refer to the *DPDK API Reference* for detailed information on the rte_eal_mp_remote_launch() function. 122