X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=doc%2Fguides%2Fsample_app_ug%2Fhello_world.rst;fp=doc%2Fguides%2Fsample_app_ug%2Fhello_world.rst;h=72e1e1152c49a9cf65696d5b0b1dd747efd39947;hb=97f17497d162afdb82c8704bf097f0fee3724b2e;hp=0000000000000000000000000000000000000000;hpb=e04be89c2409570e0055b2cda60bd11395bb93b0;p=deb_dpdk.git diff --git a/doc/guides/sample_app_ug/hello_world.rst b/doc/guides/sample_app_ug/hello_world.rst new file mode 100644 index 00000000..72e1e115 --- /dev/null +++ b/doc/guides/sample_app_ug/hello_world.rst @@ -0,0 +1,138 @@ +.. 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.